We have studied the global cloud distribution on Mars using red and blue global map swaths taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC).
\r\n\r\nIn Chapters 1 and 4, we summarize the results for the first and second MGS mapping years, respectively. In Chapter 2, we investigate the mechanism for a new type of \"flushing\" dust storm first observed by MGS. These dust storms moved from the northern high latitudes southward across the equator, and led to a planet-encircling dust storm in the first MGS mapping year (1999). In Chapter 3, we track cloud motion to measure winds using images separated by 2 hours.
\r\n\r\nThe systematic daily global coverage of MGS not only provides us with detailed and coherent pictures of Martian cloud evolution, but also increases the number of cloud-tracked wind vectors by three orders of magnitude. Except for the global dust storm in the second MGS mapping year (2001), Martian weather is highly repeatable. When the 2001 global dust storm initiated, Hellas storms increased in frequency, transporting dust out of the basin daily. When the 1999 planet-encircling dust storm initiated, \"flushing\" storms also increased in frequency, transporting dust to the southern subtropics daily. These observations suggest that timely dust supply by local or regional storms could have a global impact.
", "doi": "10.7907/CYNM-8830", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:2232", "collection": "thesis", "collection_id": "2232", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05292003-140024", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 7693697, "license": "other", "mime_type": "application/pdf", "url": "/2232/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "History and Current Processes of the Martian Polar Layered Deposits", "author": [ { "family_name": "Byrne", "given_name": "Shane", "orcid": "0000-0002-6735-4685", "clpid": "Byrne-Shane" } ], "thesis_advisor": [ { "family_name": "Gurnis", "given_name": "Michael C.", "clpid": "Gurnis-M-C" } ], "thesis_committee": [ { "family_name": "Brown", "given_name": "Michael E.", "clpid": "Brown-M-E" }, { "family_name": "Ingersoll", "given_name": "Andrew P.", "clpid": "Ingersoll-A-P" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Richardson", "given_name": "Mark I.", "clpid": "Richardson-M-I" }, { "family_name": "Gurnis", "given_name": "Michael C.", "clpid": "Gurnis-M-C" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "The Martian polar layered deposits constitute a detailed record of geologically recent environmental conditions. In this thesis I examine processes that have affected this history over timescales ranging from \u224810\u00b2 to \u224810\u2077 Martian years. To complete the work in this thesis I developed a geographic database of the Martian polar regions to enable comparisons of different datasets spread over different missions.
\r\n\r\nI report on the discovery of a large sand rich unit underlying the northern polar layered deposits. The presence of this unit suggests there once existed a radically different polar environment where there was no polar cap. A major new question now arises of where that water went during this time period and how the old polar cap (if there was one) was removed.
\r\n\r\nI describe analysis and modeling of evolving landforms on the southern residual CO\u2082 cap. This modeling suggests that these landforms are underlain by a water ice layer. THEMIS observations were used to confirm this hypothesis. This limits the size of the residual CO\u2082 cap reservoir to no more than 5% of the current atmosphere, which puts an important constraint on models of atmospheric evolution. Analysis of the size distribution coupled with this modeling indicates a uniform age for a large group of these features, implying some environmental change on the order of Martian centuries ago.
\r\n\r\nI examined geomorphologic evidence for flow processes at the margin of the south polar layered deposits. Indications of multiple episodes of previous flow are seen. However much evidence of brittle processes such as faulting, slumping and landsliding is also present. This leads to the conclusion that, during some periods, flow of the layered deposits is incapable of relieving the gravitationally generated stresses within the ice sheet. The evidence suggests that periods where flow was possible occurred intermittently and were separated by periods in which sublimation-based retreat of the ice dominated.
", "doi": "10.7907/XRZN-4T75", "publication_date": "2003", "thesis_type": "phd", "thesis_year": "2003" }, { "id": "thesis:877", "collection": "thesis", "collection_id": "877", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-03052003-124751", "primary_object_url": { "basename": "fenton_phd_doubleside.pdf", "content": "final", "filesize": 8755188, "license": "other", "mime_type": "application/pdf", "url": "/877/11/fenton_phd_doubleside.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Aeolian Processes on Mars: Atmospheric Modeling and GIS Analysis", "author": [ { "family_name": "Fenton", "given_name": "Lori Kay", "orcid": "0000-0001-8116-4901", "clpid": "Fenton-Lori-Kay" } ], "thesis_advisor": [ { "family_name": "Brown", "given_name": "Michael E.", "clpid": "Brown-M-E" } ], "thesis_committee": [ { "family_name": "Brown", "given_name": "Michael E.", "clpid": "Brown-M-E" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Sieh", "given_name": "Kerry E.", "clpid": "Sieh-K-E" }, { "family_name": "Richardson", "given_name": "Mark I.", "clpid": "Richardson-M-I" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_gps" } ], "abstract": "Wind is currently the dominant geological agent acting on the surface of Mars. A study of Martian aeolian activity leads to an understanding of the forces that have sculpted the planet's face over the past billion years or more and to the potential discovery of climate shifts recorded in surface wind features that reflect ancient wind patterns. This work takes advantage of newly available tools and data to reconstruct the sedimentary history reflected in aeolian features on Mars. The thesis is divided into two main projects. In the first section, a widely accepted hypothesis, that oscillations in Martian orbital parameters influence atmospheric circulation patterns, is challenged. A Mars global circulation model is run at different obliquity, eccentricity, and perihelion states and the predicted surface wind orientations are correlated with observed aeolian features on the Martian surface. The model indicates that orbital parameters have little effect on wind patterns, suggesting that aeolian features not aligned with the current wind regime must have formed under atmospheric conditions unrelated to orbital parameters. In the second project, new spacecraft data and a mesoscale model are used to determine the sedimentary history of Proctor Crater, a 150 km diameter crater in the southern highlands of Mars. Using high-resolution imagery, topography, composition, and thermal information, a GIS was constructed to study the aeolian history of the crater, which was found to have a complex interaction of deposition and erosion. Surficial features include 450 m of sediments filling the crater basin, small bright bedforms, dust devil tracks, and a dark dunefield consisting of coarse, basaltic sand and containing slipfaces indicative of a multidirectional, convergent wind regime. All wind features, both ancient and contemporary, are coaligned, indicating that formative wind directions have changed little since the first aeolian features formed in this area. Mesoscale model runs over Proctor Crater indicate that two dune slipfaces are created by winter afternoon geostrophic westerlies and summer evening katabatic easterlies, and that dust devil tracks are created by summer noontime rotational westerlies. Using all available tools, this thesis begins the work of understanding how aeolian processes have influenced the Martian surface.\r\n", "doi": "10.7907/C9V4-8050", "publication_date": "2003", "thesis_type": "phd", "thesis_year": "2003" }, { "id": "thesis:4431", "collection": "thesis", "collection_id": "4431", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-11072001-160517", "primary_object_url": { "basename": "01title_page.pdf", "content": "final", "filesize": 35117, "license": "other", "mime_type": "application/pdf", "url": "/4431/1/01title_page.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Low Order Model of Martian Circulation and Interannual Variability of Global Dust Storms", "author": [ { "family_name": "Pankine", "given_name": "Alexey Anatolyevich", "clpid": "Pankine-Alexey-Anatolyevich" } ], "thesis_advisor": [ { "family_name": "Ingersoll", "given_name": "Andrew P.", "orcid": "0000-0002-2035-9198", "clpid": "Ingersoll-A-P" }, { "family_name": "Muhleman", "given_name": "Duane Owen", "clpid": "Muhleman-D-O" } ], "thesis_committee": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Ingersoll", "given_name": "Andrew P.", "orcid": "0000-0002-2035-9198", "clpid": "Ingersoll-A-P" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Goldreich", "given_name": "Peter Martin", "clpid": "Goldreich-P-M" }, { "family_name": "Stevenson", "given_name": "David John", "orcid": "0000-0001-9432-7159", "clpid": "Stevenson-D-J" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_gps" } ], "abstract": "The main theme of this work is the development of a simplified model of the martian circulation suitable for conducting computationally fast long term simulations of the martian climate system. In particular, we are looking for causes of the irregular occurrence of the martian global dust storms (GDSs). The low-order model (LOM) is constructed by Galerkin projection of a 2D (zonally averaged) general circulation model (GCM) onto a truncated set of basis functions. The resulting low-order model consists of twelve coupled nonlinear ordinary differential equations (ODEs). The forcing of the model is described by simplified physics based on Newtonian cooling and Rayleigh friction. The atmosphere and surface are coupled: atmospheric heating depends on the dustiness of the atmosphere, and the surface dust source depends on the strength of the atmospheric winds. Parameters of the model are tuned to fit output of the NASA Ames GCM.
\r\n\r\nThe model performance is examined for different seasons and dust opacities and it is found that the simulated mean meridional circulation and temperature fields compare well with the more sophisticated GCM. The time of occurence and duration of the global dust storms produced by the model compare well with observations by Viking Landers (VLs). The intensity of the meridional circulation as simulated by the LOM during northern summer is stronger than that predicted by the GCM. The situation can be improved if the Rayleigh friction varies seasonally. The LOM uncoupled from the dust source can be further simplified to form the Lorenz system with forcing.
\r\n\r\nThe model is applied to the problem of interannual variability of martian global dust storms. Basic hypotheses of the intrinsic and of the extrinsic irregularity of the martian climate system are tested. The intrinsic irregularity hypothesis implies that the system under consideration is chaotic, so that small variations in initial conditions make the behavior of the system essentially unpredictable. Different paths taken by the system in state space would correspond to years with and without a GDS. The extrinsic irregularity hypothesis, on the other hand, implies that without noise the system behaves periodically, but stochastic forcing of the system causes it to behave irregularly. It is concluded that the observed variability of GDSs is more easily explained by extrinsic irregularity. The stochastic forcing (``noise') could be provided by transient weather systems or some surface process, like size sorting or redistribution of the sand particles in the ``active' (i.e., storm generating) zones on the surface. The results are very sensitive to the value of the saltation threshold, which hints at the possible feedback between saltation threshold and dust storm activity. According to this hypothesis, the saltation threshold has adjusted its value so that dust storms are barely able to occur.
", "doi": "10.7907/MGSA-ZT98", "publication_date": "2001", "thesis_type": "phd", "thesis_year": "2001" }, { "id": "thesis:7433", "collection": "thesis", "collection_id": "7433", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01242013-112821494", "primary_object_url": { "basename": "Toigo 2001.pdf", "content": "final", "filesize": 34046802, "license": "other", "mime_type": "application/pdf", "url": "/7433/1/Toigo 2001.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Behavior of Dust in the Martian Atmosphere", "author": [ { "family_name": "Toigo", "given_name": "Anthony Domenick", "clpid": "Toigo-Anthony-Domenick" } ], "thesis_advisor": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" } ], "thesis_committee": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Yung", "given_name": "Yuk L.", "orcid": "0000-0002-4263-2562", "clpid": "Yung-Y-L" }, { "family_name": "Richardson", "given_name": "Mark I.", "clpid": "Richardson-M-I" }, { "family_name": "Ingersoll", "given_name": "Andrew P.", "orcid": "0000-0002-2035-9198", "clpid": "Ingersoll-A-P" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_gps" } ], "abstract": "Two aspects of the dust cycle on Mars are examined: the seasonal variation of dust aerosols\r\nin the atmosphere as observed by spacecraft and dust lifting by high wind stress at the south\r\npole during late spring employing a specially developed mesoscale atmospheric model. Reanalysis\r\nof Viking mission optical depth measurements shows that the visible to infrared\r\nratio of total extinction opacity varies with season, and is due to seasonally varying water\r\nice haze. The Martian atmosphere is clearer of dust, especially during northern spring and\r\nsummer, than previously thought. Water ice hazes can provide roughly 50% of the total\r\nvisible opacity in these seasons, and that they represent only 1-5% of the total water column.\r\nNext, the conversion for use on Mars of a terrestrial mesoscale atmospheric model\r\n(the Mars MM5) is presented and described. Validation of the Mars MM5 is conducted\r\nby comparison with a general circulation model on scales of a few hundred kilometers and\r\nwith Martian surface landers (Viking Lander 1, Viking Lander 2, and Mars Pathfinder)\r\non scales of a few kilometers, and in both cases there is good agreement in the meteorological\r\nvariables of temperature, pressure, and wind. Tides are found to be at least as\r\nimportant as slopes in generating the diurnal cycle of winds at the lander sites, in contrast\r\nto previous one-dimensional studies. Finally, assuming that dust injection is related to the\r\nmovement of sand-sized grains or aggregates, the Mars MM5 predicts wind stresses of sufficient\r\nstrength to initiate movement of sand-sized particles, and hence dust lifting, during\r\nlate southern spring in the south polar region. It is found that the direct cap edge thermal\r\ncontrast provides the primary drive for high surface wind stresses at the cap edge at this season\r\nwhile sublimation flow is not found to be particularly important. Comparison between\r\nsimulations, in which dust is injected when wind stresses are high and those with inactive\r\ndust injection, show no signs of consistent feedback due to dust clouds on the surface wind stress fields during the late spring season examined here.\r\n", "doi": "10.7907/7v06-j640", "publication_date": "2001", "thesis_type": "phd", "thesis_year": "2001" }, { "id": "thesis:5736", "collection": "thesis", "collection_id": "5736", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04222010-100328955", "primary_object_url": { "basename": "Haldemenn_afc_1997.pdf", "content": "final", "filesize": 37232907, "license": "other", "mime_type": "application/pdf", "url": "/5736/1/Haldemenn_afc_1997.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Interpreting Radar Scattering: Circular-Polarization Perspectives from Three Terrestrial Planets", "author": [ { "family_name": "Haldemann", "given_name": "Albert Frank Christian", "clpid": "Haldemann-Albert-Frank-Christian" } ], "thesis_advisor": [ { "family_name": "Muhleman", "given_name": "Duane Owen", "clpid": "Muhleman-D-O" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" } ], "thesis_committee": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Ingersoll", "given_name": "Andrew P.", "clpid": "Ingersoll-A-P" }, { "family_name": "Kamb", "given_name": "W. Barclay", "clpid": "Kamb-W-B" }, { "family_name": "Muhleman", "given_name": "Duane Owen", "clpid": "Muhleman-D-O" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "Planetary radar astronomy has used circular polarization radar signals to probe the surfaces of many solar system targets. However the trend for terrestrial observations has been toward greater use of linearly polarized imaging radars. Fortunately the latest generation of imaging radars has been developed with a multi-polarization capability. This should allow a synergy of the two research communities to occur.
\r\n\r\nOne of the unresolved debates on planetary radar astronomy is the nature of the scattering processes from cold planetary ices. This question recently received input from a terrestrial source: Greenland (Rignot et al. 1993). In this thesis a survey is made of high altitude sites to discover if the Greenland percolation zone scattering behavior is wide-spread on the Earth. The survey was carried out with the enormous, publicly available dataset from the 1994 missions of Shuttle Imaging Radar payload. This instrument (SIR-C) obtained full-polarization information with its linear-polarization system. These data allow reconstruction of circular polarizations for comparison to planetary results. The search proved fruitful. Hundreds of square kilometers in western Tibet's Kunlun Shan, and in the Central Andes at the latitude of Santiago display radar scattering behavior quite similar to that in Greenland where internal reflections of the radar waves within icy inclusions in the firn enhance scattering in the same sense of circular polarization.
\r\n\r\nA separate unresolved issue in the planetary radar astronomy is the question of the nature of the highlands of Venus that exhibit high radar reflectivity and low emissivity. These so-called anomalous radar behavior in these regions have alternately been ascribed to high-dielectric doping or low dielectric volume scatterinig. We present new dual circular-polarization radar maps of the western hemisphere of Venus. The results are from a 1993 experiment to image Venus with 3.5 cm radar. Maps of Venusian radar albedo were made for each of two days of observation in both OS (echo principally due to specular reflection) and SS (diffuse echo) channels. On both days, the sub-earth longitude was near 300E. The SS maps are dominated by a significant component of diffuse backscatter from the 285E longitude highlands: Beta, Phoebe, and Themis Regiones. Beta Regio includes previously observed radar-anomalous regions. The nature of these altitude-related electrical properties on Venus is one of the outstanding surface process questions that remain after the Magellan mission. Our experiment provides the first full-disk polarization ratio (\u00b5_c) maps. The data show that different geology determines different radar scattering properties within Beta. Diffuse scattering is very important in Beta, and may be due to either surface or volume scattering. We find a strong correlation of the SS albedo \u03c3_(SS) with altitude R_p (km) in Beta, \u03c3_(SS) \u221d0.3R_p. Also, \u03c3_(OS) \u221d0.7 R_p. The onset of this relationship is at the R_p~6054 km planetary radius contour. The nature and morphology of the highland radar anomalies in Beta is consistent with a diffuse scattering mechanism. In Beta Regio we find \u00b5_c > 0.5 in general, with \u00b5_c as high as 0.8 between Rhea and Theia Montes, to the west of Devana Chasma. These values are compatible with measurements of blocky terrestrial lava flows if surface scattering dominates. If volume scattering is important, the high RCP cross-sections may indicate an important decrease in embedded scatterer size with altitude, which could be related to enhanced weathering.
\r\n\r\nFinally, the techniques of planetary radar astronomy were used in an applied sense. Results are presented of 3.5-cm delay-Doppler and Doppler-only (continuous wave or CW) radar experiments to assess three potential Mars Pathfinder landing sites: Ares Vallis, Tritonis Lacus, and northwest (NW) Isidis. The regional relief at all of the landing sites is appropriate for a Pathfinder landing sequence: east-west slopes do not exceed 3\u00b0 at any of the sites. We find that Ares Vallis has a Hagfors rms slope of \u03b8_(rms)=4.8\u00b0\u00b11.1\u00b0 as measured by delay-Doppler radar, and \u03b8_(rms)=6.4\u00b0\u00b10.6\u00b0 measured by CW radar. These values are similar to, or less than the previous measurements of the Viking Lander 1 region (\u03b8_(rms)=6\u00b0, Tyler et al. 1976, Harmon 1997). The Tritonis Lacus landing site is rougher with delay- Doppler, \u03b8_(rms)=5.6\u00b0\u00b10.6\u00b0, while the NW Isidis landing site is very smooth, both in a regional sense (slopes < 0.7\u00b0) and in a Hagfors rms slope sense: \u03b8_(rms)=1.8\u00b0\u00b10.2\u00b0. Reflectivities at all of the sites should be sufficient to allow the radar altimeter on Pathfinder to function properly.
\r\n", "doi": "10.7907/YQ6F-ZS42", "publication_date": "1997", "thesis_type": "phd", "thesis_year": "1997" }, { "id": "thesis:15047", "collection": "thesis", "collection_id": "15047", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10252022-202940570", "primary_object_url": { "basename": "Holk_GJ_1997.pdf", "content": "final", "filesize": 201279911, "license": "other", "mime_type": "application/pdf", "url": "/15047/1/Holk_GJ_1997.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Role of Water in the Magmatic and Tectonic Evolution of Metamorphic Core Complexes: A stable Isotope Study of the Southern Omineca Crystalline Belt, British Columbia, Canada", "author": [ { "family_name": "Holk", "given_name": "Gregory James", "clpid": "Holk-Gregory-James" } ], "thesis_advisor": [ { "family_name": "Taylor", "given_name": "Hugh P., Jr.", "clpid": "Taylor-H-P" }, { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" } ], "thesis_committee": [ { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" }, { "family_name": "Taylor", "given_name": "Hugh P., Jr.", "clpid": "Taylor-H-P" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Wernicke", "given_name": "Brian P.", "orcid": "0000-0002-7659-8358", "clpid": "Wernicke-B-P" }, { "family_name": "Wyllie", "given_name": "Peter J.", "clpid": "Wyllie-P-J" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "The oxygen isotope data in this study delineate 2 major episodes of water-rock interaction related to the metamorphic, plutonic, and tectonic development of the metamorphic core complexes in the southern Omineca belt. Episode 1 is a Paleocene pre\u00ad-extensional metamorphic/magmatic-hydrothermal event. The occurrence of isotopically uniform quartz (\u03b4\u00b9\u2078O = 12.5 \u00b1 0.5\u2030) and feldspar (10.9 \u00b1 0.7\u2030) throughout different rock types indicates that much of a 6-km-thick section of the mid-crustal Selkirk allochthon underwent internally buffered \u00b9\u2078O/\u00b9\u2076O homogenization during Paleocene melting and decompression as it moved up the Monashee decollement thrust ramp. Areas of uniform \u03b4\u00b9\u2078O are those with the most leucogranite or those subjected to severe anatexis. Only locally, in the most impermeable (or refractory) zones did 180 exchange among the rocks, leucogranite melts, and aqueous fluids fail to go to completion (i.e., in the deepest parts of the section, in a marble-rich zone, around some thick amphibolites, and in most garnets). Evidence for \u00b9\u2078O/\u00b9\u2076O heterogeneity in the protoliths of these rocks is observed in stratigraphically correlative lower-grade units elsewhere in British Columbia, as well as in garnets that coexist with isotopically homogeneous quartz. A model is introduced utilizing water as a petrologic catalyst: fluids evolved during muscovite breakdown and partial melting of pelites produce \u00b9\u2078O/\u00b9\u2076O homogenization with only minor influx of external H\u2082O; this is followed by release of magmatic H\u2082O from these melts as they crystallize (triggering further melting of adjacent feldspathic assemblages) during and after the ~20 km uplift that occurred in the thrusting event that took place just prior to detachment faulting.
\r\n \r\nEpisode 2 is a series of Eocene synextensional meteoric-hydrothermal events affecting the shallow crust along all of the major detachment faults in the region, and along some parts of the Monashee decollement; these effects were locally enhanced by added heat from some synextensional alkaline intrusions (the Coryell plutons). Very large quartz-feldspar \u00b9\u2078O/\u00b9\u2076O disequilibrium effects were imprinted upon the rocks during exchange with hot meteoric waters (initial \u03b4\u00b9\u2078O ~ -15); the mineral most affected was feldspar (\u03b4\u00b9\u2078O down to -5.0). In the Valhalla core complex, the hanging wall rocks above the Slocan Lake fault are sufficiently uniform to allow us to apply open-system kinetic oxygen isotope exchange modeling, thereby placing constraints on the duration (1-3 Ma) and integrated fluid flux (\u2265 10\u2077 cm\u00b3H\u2082O/cm\u2082rock) for this hydrothermal metamorphism.
", "doi": "10.7907/pkn3-p364", "publication_date": "1997", "thesis_type": "phd", "thesis_year": "1997" }, { "id": "thesis:4423", "collection": "thesis", "collection_id": "4423", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-11062007-083125", "primary_object_url": { "basename": "Ray_tw_1995.pdf", "content": "final", "filesize": 60568633, "license": "other", "mime_type": "application/pdf", "url": "/4423/1/Ray_tw_1995.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Remote monitoring of land degradation in arid/semiarid regions", "author": [ { "family_name": "Ray", "given_name": "Terrill Wylie", "clpid": "Ray-T-W" } ], "thesis_advisor": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" } ], "thesis_committee": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Anderson", "given_name": "Donald L.", "clpid": "Anderson-D-L" }, { "family_name": "Muhleman", "given_name": "Duane Owen", "clpid": "Muhleman-D-O" }, { "family_name": "Wyllie", "given_name": "Peter J.", "clpid": "Wyllie-P-J" }, { "family_name": "Blom", "given_name": "Ron", "clpid": "Blom-R" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nLand degradation is a serious and growing problem on a world-wide scale -- 11% of the Earth's vegetated surface having suffered serious damage in the last 45 years. Human activity, especially sprinkler irrigation agriculture, can cause dramatic changes in arid regions as the fragile natural plant cover is stripped off and its root system destroyed in the process of cultivation. Satellite and airborne remote sensing data covering the Manix Basin of Eastern California over the last two decades shows that abandoned fields there suffered progressive degradation, as the topsoil eroded due to the lack of protective plant cover. Blowing sand buried and disrupted the downwind plant cover, which caused the downwind area to lose its protection against wind erosion and expanded the region of damage.\r\n\r\nBecause the amount and kind of plant cover is an important marker both of where wind erosion has occurred and where it is likely to occur in the future, especially designed satellite monitoring systems should be able to sense to signatures of undisturbed and disturbed vegetation cover in arid regions. However, this problem cannot be addressed by standard vegetation indices, because of the adaptation of arid region plants to the scarcity of water. Furthermore, weekly to monthly sampling will be necessary because blowing sand visible to satellite remote sensing is highly dependent on the local weather, and this can change within a few months. A new vegetative index suitable for arid regions is proposed for the wavelength region from 0.4-1.0 [...].\r\n\r\nThe detection and identification of arid region plant communities requires a highly calibrated remote sensing system with higher spectral resolution than that currently offered by Landsat Thematic Mapper. The way in which regions of blowing sand can appear and disappear with rapidity demonstrates the need for a remote monitoring system that can survey large areas on a regular basis. Such a system must be supported by focused ground observations and a continuing analysis of the satellite data.\r\n", "doi": "10.7907/65EA-Y568", "publication_date": "1995", "thesis_type": "phd", "thesis_year": "1995" }, { "id": "thesis:7525", "collection": "thesis", "collection_id": "7525", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03182013-160237674", "primary_object_url": { "basename": "Keszthelyi_lp_1994.pdf", "content": "final", "filesize": 51471055, "license": "other", "mime_type": "application/pdf", "url": "/7525/1/Keszthelyi_lp_1994.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "On the Thermal Budget of Pahoehoe Lava Flows", "author": [ { "family_name": "Keszthelyi", "given_name": "L\u00e1szl\u00f3 P.", "clpid": "Keszthelyi-L\u00e1szl\u00f3-P" } ], "thesis_advisor": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" } ], "thesis_committee": [ { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Denlinger", "given_name": "Roger", "clpid": "Denlinger-R" }, { "family_name": "Stock", "given_name": "Joann M.", "orcid": "0000-0003-4816-7865", "clpid": "Stock-J-M" }, { "family_name": "Stolper", "given_name": "Edward M.", "orcid": "0000-0001-8008-8804", "clpid": "Stolper-E-M" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "In this thesis I investigate some aspects of the thermal budget of pahoehoe lava\r\nflows. This is done with a combination of general field observations, quantitative\r\nmodeling, and specific field experiments. The results of this work apply to pahoehoe\r\nflows in general, even though the vast bulk of the work has been conducted on the lavas\r\nformed by the Pu'u 'O'o - Kupaianaha eruption of Kilauea Volcano on Hawai'i. The field\r\nobservations rely heavily on discussions with the staff of the United States Geological\r\nSurvey's Hawaiian Volcano Observatory (HVO), under whom I labored repeatedly in\r\n1991-1993 for a period totaling about 10 months.
\r\n\r\nThe quantitative models I have constructed are based on the physical processes\r\nobserved by others and myself to be active on pahoehoe lava flows. By building up these\r\nmodels from the basic physical principles involved, this work avoids many of the pitfalls of\r\nearlier attempts to fit field observations with \"intuitively appropriate\" mathematical\r\nexpressions. Unlike many earlier works, my model results can be analyzed in terms of the\r\ninteractions between the different physical processes. I constructed models to: (1) describe\r\nthe initial cooling of small pahoehoe flow lobes and (2) understand the thermal budget of\r\nlava tubes.
\r\n\r\nThe field experiments were designed either to validate model results or to constrain\r\nkey input parameters. In support of the cooling model for pahoehoe flow lobes, attempts\r\nwere made to measure: (1) the cooling within the flow lobes, (2) the amount of heat\r\ntransported away from the lava by wind, and (3) the growth of the crust on the lobes.\r\nField data collected by Jones [1992], Hon et al. [1994b], and Denlinger [Keszthelyi and\r\nDenlinger, in prep.] were also particularly useful in constraining my cooling model for\r\nflow lobes. Most of the field observations I have used to constrain the thermal budget of\r\nlava tubes were collected by HVO (geological and geophysical monitoring) and the Jet\r\nPropulsion Laboratory (airborne infrared imagery [Realmuto et al., 1992]). I was able to\r\nassist HVO for part of their lava tube monitoring program and also to collect helicopterborne\r\nand ground-based IR video in collaboration with JPL [Keszthelyi et al., 1993].
\r\n\r\nThe most significant results of this work are (1) the quantitative demonstration that\r\nthe emplacement of pahoehoe and 'a'a flows are the fundamentally different, (2)\r\nconfirmation that even the longest lava flows observed in our Solar System could have\r\nformed as low effusion rate, tube-fed pahoehoe flows, and (3) the recognition that the\r\natmosphere plays a very important role throughout the cooling of history of pahoehoe lava\r\nflows. In addition to answering specific questions about the thermal budget of tube-fed\r\npahoehoe lava flows, this thesis has led to some additional, more general, insights into the\r\nemplacement of these lava flows. This general understanding of the tube-fed pahoehoe\r\nlava flow as a system has suggested foci for future research in this part of physical\r\nvolcanology.
", "doi": "10.7907/G5V5-T293", "publication_date": "1994", "thesis_type": "phd", "thesis_year": "1994" }, { "id": "thesis:933", "collection": "thesis", "collection_id": "933", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-03112009-141429", "primary_object_url": { "basename": "Svitek_t_1992.pdf", "content": "final", "filesize": 9657969, "license": "other", "mime_type": "application/pdf", "url": "/933/1/Svitek_t_1992.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Martian water frost : control of global distribution by small-scale processes", "author": [ { "family_name": "Svitek", "given_name": "Tomas", "clpid": "Svitek-T" } ], "thesis_advisor": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" } ], "thesis_committee": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Ingersoll", "given_name": "Andrew P.", "clpid": "Ingersoll-A-P" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Kamb", "given_name": "W. Barclay", "clpid": "Kamb-W-B" }, { "family_name": "Stevenson", "given_name": "David John", "clpid": "Stevenson-D-J" }, { "family_name": "Muhleman", "given_name": "Duane Owen", "clpid": "Muhleman-D-O" }, { "family_name": "Goldreich", "given_name": "Peter Martin", "clpid": "Goldreich-P-M" }, { "family_name": "Yung", "given_name": "Yuk L.", "clpid": "Yung-Y-L" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "This thesis analyzes the small\u2014scale physical processes occurring in the Martian water polar frosts. The small\u2014scale processes are considered from the point of view of how they control the global distribution and behavior of water on Mars. The analysis of the small\u2014scale properties of the surface frost is essential in efforts to find solutions for some outstanding, contradictory observations, to interpret correctly remote sensing observations, to model the surface\u2014frost thermal balance, and to implement the boundary conditions and parameterizations used in the global models of the volatiles' behavior on Mars. Two different problems are investigated in this thesis:\r\n\r\nThe effect of surface roughness on frost temperature and morphology is studied in Chapter 2 and 3. The investigation of the temperature/roughness feedback leads to the following suggestion: There is a natural tendency of volatile surfaces to develop spontaneously small-scale roughness in a sublimation\u2014dominated environment. The evidence for this claim consists of the model of a rough\u2014surface thermal balance, and of the terrestrial analogs of differential sublimation structures. Such a phenomenon can be tested by the Mars Observer and has important implications for the behavior of water frost on Mars.\r\n\r\nViking Lander 2 winter\u2014frost observations are described in Chapter 4. This study suggests that winter water frost occurred there in two forms: a) thin, almost continuous, early frost, and b) much thicker, patchy, later frost with local cold\u2014trapping of water vapor playing the crucial role. This conclusion is based on the correlation of multiple data sets (from both Viking Orbiter and Lander) and on the combined models of the physical processes occurring on a small scale \u2014 below the resolution of remote sensing. The evidence consists of the frost\u2014surface coverage and color transitions, and of the calculation of the vertical and horizontal water\u2014vapor transport near the surface. Again, this phenomenon can be confirmed or rejected by a set of observations from the Mars Observer.\r\n\r\nThe inherent rough\u2014surface morphology and the frost cold\u2014trapping must be a general property of at least some forms of the seasonal and residual frosts. Both effects must be considered in order to understand the global observations of the Martian frost and the surface environment of Mars in general.\r\n", "doi": "10.7907/EDK8-3457", "publication_date": "1992", "thesis_type": "phd", "thesis_year": "1992" }, { "id": "thesis:6347", "collection": "thesis", "collection_id": "6347", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04222011-143434002", "type": "thesis", "title": "Geologic and isotopic investigations of the early Cretaceous Sierra Nevada Batholith, Tulare Co., CA, and the Ivrea Zone, NW Italian Alps: examples of interaction between mantle-derived magma and continental crust", "author": [ { "family_name": "Knott", "given_name": "Diane Clemens", "clpid": "Knott-D-C" } ], "thesis_advisor": [ { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" }, { "family_name": "Saleeby", "given_name": "Jason B.", "clpid": "Saleeby-J-B" } ], "thesis_committee": [ { "family_name": "Wyllie", "given_name": "Peter J.", "clpid": "Wyllie-P-J" }, { "family_name": "Stolper", "given_name": "Edward M.", "clpid": "Stolper-E-M" }, { "family_name": "Epstein", "given_name": "Samuel", "clpid": "Epstein-S" }, { "family_name": "Rossman", "given_name": "George Robert", "clpid": "Rossman-G-R" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" }, { "family_name": "Saleeby", "given_name": "Jason B.", "clpid": "Saleeby-J-B" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "Two igneous suites containing layered ultramafic-mafic cumulates were investigated with the intent to characterize the parental magma and to identify processes significant to the petrogenesis of these rocks. In both study areas, the early Cretaceous Sierra Nevada batholith and the Ivrea Zone, isotopic systematics of the cumulates were found to preserve the characteristics of the mantle-derived parental magma and to record the effects of fractional crystallization and assimilation. Modeling the relative importance of these processes and characterization of the material derived from the mantle are necessary to understanding the growth of the continental crust.
\r\n\r\nGeologic mapping of 110 mi2 of the 125 to 110 Ma Stokes Mountain region reveals the presence of layered cumulate megaxenoliths and two coeval ring dike complexes. Petrographic analysis and geochemical modeling of 125 dominantly mafic and intermediate samples demonstrate the comagmatic nature of this suite. Combined oxygen, strontium and neodymium analysis of 22 samples indicates, however, that each ring complex was fed by an isotopically distinct parental magma (\u03b5Nd(115) = +6.1, Sri = 0.70338, \u03b418O = 6.6\u2030 ; (\u03b5Nd(115) = +5.7, Sri = 0.70372, \u03b418O = 6.7\u2030) both of which were derived from a variably contaminated, depleted mantle source. Minor assimilation of continentally-derived metasediments and mafic-ultramafic material of the Kings-Kaweah ophiolite further affected the isotopic evolution of the two subsuites. Hydrothermal alteration in the subvolcanic environment is recorded only by rare stoped xenoliths of 120 Ma hypabyssal intrusives.
\r\n\r\nLate Hercynian (\u2248300 - 270 Ma) magmatism produced the 10 km thick Mafic Complex lying at the base of the Ivrea-Strona-Ceneri crustal cross section. \u03b418O analysis of 237 whole rock samples and 26 mineral separates reveals that presumably early intrusions into the cool crust preserve the depleted mantle signature of the modeled parental magma (\u03b5Nd(115) = +7, Sri = 0.703, \u03b418O = 6.5\u2030) while later intrusions assimilated significant amounts of the 10 - 12\u2030 metapelite. Subsequent intrusion of voluminous basaltic magma fonned a large, convecting magma chamber in which assimilation was concentrated within boundary layers. Such lower crustal production of high-18O (\u03b418O = 8 - 10\u2030) mafic magmas is suggested as contributing to the petrogenesis of upper crustal Permian granites.
\r\n", "doi": "10.7907/AA6N-EY25", "publication_date": "1992", "thesis_type": "phd", "thesis_year": "1992" }, { "id": "thesis:8781", "collection": "thesis", "collection_id": "8781", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03182015-092735941", "primary_object_url": { "basename": "Anderson_ww_1990.pdf", "content": "final", "filesize": 31311830, "license": "other", "mime_type": "application/pdf", "url": "/8781/1/Anderson_ww_1990.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "High Pressure States in Condensed Matter: I. High Pressure Behavior of the Iron-Sulfur System with Applications to the Earth's Core. II. Empirical Equation of State for Organic Compounds at High Pressures", "author": [ { "family_name": "Anderson", "given_name": "William Wyatt", "clpid": "Anderson-William-Wyatt" } ], "thesis_advisor": [ { "family_name": "Ahrens", "given_name": "Thomas J.", "clpid": "Ahrens-T-J" }, { "family_name": "Stevenson", "given_name": "David John", "orcid": "0000-0001-9432-7159", "clpid": "Stevenson-D-J" } ], "thesis_committee": [ { "family_name": "Stevenson", "given_name": "David John", "orcid": "0000-0001-9432-7159", "clpid": "Stevenson-D-J" }, { "family_name": "Ahrens", "given_name": "Thomas J.", "clpid": "Ahrens-T-J" }, { "family_name": "Anderson", "given_name": "Donald L.", "clpid": "Anderson-D-L" }, { "family_name": "Burnett", "given_name": "Donald S.", "clpid": "Burnett-D-S" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "Part I:
\r\n\r\nThe earth's core is generally accepted to be composed primarily of iron, with an admixture of other elements. Because the outer core is observed not to transmit shear waves at seismic frequencies, it is known to be liquid or primarily liquid. A new equation of state is presented for liquid iron, in the form of parameters for the 4th order Birch-Murnaghan and Mie-Gr\u00fcneisen equations of state. The parameters were constrained by a set of values for numerous properties compiled from the literature. A detailed theoretical model is used to constrain the P-T behavior of the heat capacity, based on recent advances in the understanding of the interatomic potentials for transition metals. At the reference pressure of 105 Pa and temperature of 1811 K (the normal melting point of Fe), the parameters are: \u03c1 = 7037 kg/m3, KS0 = 110 GPa, KS' = 4.53, KS\" = -.0337 GPa-1, and \u03b3 = 2.8, with \u03b3 \u221d \u03c1-1.17. Comparison of the properties predicted by this model with the earth model PREM indicates that the outer core is 8 to 10 % less dense than pure liquid Fe at the same conditions. The inner core is also found to be 3 to 5% less dense than pure liquid Fe, supporting the idea of a partially molten inner core. The density deficit of the outer core implies that the elements dissolved in the liquid Fe are predominantly of lower atomic weight than Fe. Of the candidate light elements favored by researchers, only sulfur readily dissolves into Fe at low pressure, which means that this element was almost certainly concentrated in the core at early times. New melting data are presented for FeS and FeS2 which indicate that the FeS2 is the S-hearing liquidus solid phase at inner core pressures. Consideration of the requirement that the inner core boundary be observable by seismological means and the freezing behavior of solutions leads to the possibility that the outer core may contain a significant fraction of solid material. It is found that convection in the outer core is not hindered if the solid particles are entrained in the fluid flow. This model for a core of Fe and S admits temperatures in the range 3450K to 4200K at the top of the core. An all liquid Fe-S outer core would require a temperature of about 4900 K at the top of the core.
\r\n\r\nPart II.
\r\n\r\nThe abundance of uses for organic compounds in the modern world results in many applications in which these materials are subjected to high pressures. This leads to the desire to be able to describe the behavior of these materials under such conditions. Unfortunately, the number of compounds is much greater than the number of experimental data available for many of the important properties. In the past, one approach that has worked well is the calculation of appropriate properties by summing the contributions from the organic functional groups making up molecules of the compounds in question. A new set of group contributions for the molar volume, volume thermal expansivity, heat capacity, and the Rao function is presented for functional groups containing C, H, and O. This set is, in most cases, limited in application to low molecular liquids. A new technique for the calculation of the pressure derivative of the bulk modulus is also presented. Comparison with data indicates that the presented technique works very well for most low molecular hydrocarbon liquids and somewhat less well for oxygen-bearing compounds. A similar comparison of previous results for polymers indicates that the existing tabulations of group contributions for this class of materials is in need of revision. There is also evidence that the Rao function contributions for polymers and low molecular compounds are somewhat different.
", "doi": "10.7907/7dsx-ed25", "publication_date": "1990", "thesis_type": "phd", "thesis_year": "1990" }, { "id": "thesis:2512", "collection": "thesis", "collection_id": "2512", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06072007-141923", "type": "thesis", "title": "Quantitative Studies of the Martian South Polar Region Using Spacecraft Images", "author": [ { "family_name": "Herkenhoff", "given_name": "Kenneth Edward", "clpid": "Herkenhoff-Kenneth-Edward" } ], "thesis_advisor": [ { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Stevenson", "given_name": "David John", "orcid": "0000-0001-9432-7159", "clpid": "Stevenson-D-J" } ], "thesis_committee": [ { "family_name": "Stevenson", "given_name": "David John", "orcid": "0000-0001-9432-7159", "clpid": "Stevenson-D-J" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Ingersoll", "given_name": "Andrew P.", "orcid": "0000-0002-2035-9198", "clpid": "Ingersoll-A-P" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "Spacecraft observations must be calibrated absolutely in order to investigate the photometric properties of the Martian surface and atmosphere. The accuracy of the Mariner 9 and Viking Orbiter television system calibration was evaluated by comparing the two data sets with each other and with Earth-based spectrophotometry of Mars and Phobos. The Viking imaging data are consistent with published estimates of the geometric albedo of Phobos, which is uncertain by about 20%. Mariner 9 data are calibrated to within about \u00b120% by comparing Phobos images with Viking data. Better photometric observations of Phobos are necessary to improve the calibration of the Viking Orbiter and Mariner 9 television systems. Similarly, inflight Phobos observations should be used to calibrate imaging systems on future Mars missions.
\r\n\r\nMariner 9 images were processed for comparison with nearly simultaneous infrared spectra of the south polar cap of Mars recorded in 1971-72. Combined analysis of these observations indicates that the southern residual cap was covered by carbon dioxide frost throughout the summer, in agreement with Viking Orbiter measurements made three Mars years later. Thermal modeling of the spectra shows that areas of intermediate albedo are cooled to the sublimation temperature of CO2, suggesting that frost is present but not visible. Topographic roughness may shade the CO2 from the sun and produce the variegated appearance of the residual cap.
\r\n\r\nFive color/albedo units, including polar frost, have been recognized and mapped in the southern layered deposits on Mars. Atmospheric dust scattering was measured in shadows and modeled in order to remove the component of brightness due to the atmosphere and quantify the albedo and color of the surface. The layered deposits appear to be mantled by red dust, except where eolian stripping has exposed the underlying bedrock. Frost and bare ground are mixed below the resolution of the images in many areas adjacent to the polar cap, some of which appear to be younger than the surrounding layered terrain. Dark material has been deposited in topographic depressions in much of the south polar region, including the layered deposits. The available observational data suggest that the layered deposits are composed of bright dust, ice, and a small amount of dark material. If the dark material is sand, a periodic change in polar winds seems required in order to transport the sand poleward into the layered terrain. In any case, the observations are not consistent with the layered deposits being composed only of bright dust and ice.
\r\n\r\nMaximum slopes of 10-20 degrees occur on an exposure of layered deposits within the south polar residual cap of Mars. A new photoclinometric technique is used to produce profiles of slope and albedo using high resolution Mariner 9 images. Stereophotogrammetry is also used to constrain the photoclinometric solutions, which resolve layer thicknesses of 100-300 meters. The results are limited by the ~200 meter resolution of the images, and thinner (unresolved) layers are likely. The ~25% maximum albedo variations are correlated with slope, indicating that frost is present on level areas. There is evidence for temporal changes in frost distribution in the 7 days (4\u00b0 of Ls) between the two images used in this study, demonstrating that future photoclinometric studies of the polar regions must be attempted carefully. The magnitude of the slopes derived here suggest that the layers are competent, perhaps due to the presence of a weathering rind.
\r\n\r\nWeathering of the layered deposits by sublimation of water ice can account for the data presented here and previous observations of the north polar deposits. The non-volatile component of the layered deposits appears to consist mainly of bright red dust, with small amounts of dark dust or sand. Deposition of sand in the layered deposits is problematical, so inclusion of dark dust is preferred. The dark dust may be similar to the magnetic material found at the Viking Lander sites, and may therefore preferentially form ~ 100\u00b5 filamentary residue particles upon weathering. Once eroded from the layered deposits, these particles may then saltate to form the dark sand dunes found in both polar regions. Eventual destruction of the particles could allow recycling of the dark dust into the layered deposits via atmospheric suspension.
", "doi": "10.7907/bty4-vk56", "publication_date": "1989", "thesis_type": "phd", "thesis_year": "1989" }, { "id": "thesis:490", "collection": "thesis", "collection_id": "490", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-02042005-111245", "primary_object_url": { "basename": "Manduca_cca_1988.pdf", "content": "final", "filesize": 22647149, "license": "other", "mime_type": "application/pdf", "url": "/490/21/Manduca_cca_1988.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Geology and Geochemistry of the Oceanic Arc-Continent Boundary in the Western Idaho Batholith near McCall", "author": [ { "family_name": "Manduca", "given_name": "Cathryn Clement Allen", "clpid": "Manduca-Cathryn-Clement-Allen" } ], "thesis_advisor": [ { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" }, { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" } ], "thesis_committee": [ { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" }, { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" }, { "family_name": "Saleeby", "given_name": "Jason B.", "clpid": "Saleeby-J-B" }, { "family_name": "Stevenson", "given_name": "David John", "clpid": "Stevenson-D-J" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "A major lithospheric boundary is preserved within the western Idaho Batholith. The juxtaposition of two suites of supracrustal rocks, exposed as sheets within intrusive rocks, is the expression of this boundary at the level of exposure. The western suite of mafic layered gneisses are inferred to be metamorphosed oceanic arc rocks; the eastern suite of biotite schist, quartzite and calc-silicate gneiss are inferred to be metamorphosed continental sedimentary rocks. Three broadly Cretaceous, plutonic and meta-plutonic complexes record the presence of the boundary at greater depth. The Hazard Creek complex, west of the supracrustal boundary, is comprised of epidote-bearing intrusives. The Little Goose Creek complex is comprised primarily of the porphyritic orthogneiss that intruded the supracrustal boundary. The Payette River complex, east of the supracrustal boundary, is comprised of large bodies of tonalite and granite.
\r\n\r\nEach complex has a distinct geochemical character. The Hazard Creek complex is dominantly a tonalite-trondhjemite suite characterized by Ri less than .7045, \u03b4\u00b9\u2078O less than 8.4, high Sr, Na\u2082O and Al\u2082O\u2083 concentrations and low MgO, Rb and K\u2082O concentrations. Porphyritic orthogneiss in the Little Goose Creek complex has a remarkable range in Ri and \u03b4\u00b9\u2078O (.7042-.7097, 8.0-10.7). The porphyritic orthogneiss is interpreted as dominated by two components: one similar in composition to the Hazard Creek complex and a second, modeled as Precambrian sedimentary material, with high Ri, \u03b4\u00b9\u2078O and K\u2082O concentrations and lower Sr concentration. The Payette River complex has generally high Ri (.7076-.7100) and variable \u03b4\u00b9\u2078O (7.2-10.4). The geochemical changes indicate that the supracrustal boundary is the surface expression of a steeply-dipping structure which juxtaposes oceanic-arc lithosphere against continental lithosphere. An abrupt geochemical discontinuity preserved within the porphyritic orthogneiss, near the change in supracrustal rocks, may reflect an abrupt discontinuity at depth or may be due to the juxtapositon of portions of a stratified pluton. The juxtaposition of lithospheric blocks must have occured prior to intrusion of the porphyritic orthogneiss approximately 111 Ma, and most probably, occured before 118 Ma, prior to the beginning of plutonism. No structural evidence for the initial formation of the boundary is recognized; it is proposed to form by transform faulting or by rifting followed by convergence.
\r\n\r\nEpisodic or continuous deformation along the boundary began prior to 118 Ma and produced four sets of structures. The oldest structures are foliation and isoclinal folding of crystalloblastic gneisses which may have formed during rapid burial of oceanic-arc rocks west of the boundary. Compressive deformation, forming north-south striking steeply-dipping foliations and steeply-plunging lineations in the eastern portion of the Hazard Creek complex, was broadly coeval with its emplacement. Igneous foliation and lineation with similar orientation formed during emplacement of the Payette River complex around 90 Ma. The youngest penetrative deformation formed similarly oriented, mylonitic fabrics in a 10 km wide zone centered on the boundary. All but the oldest structures are inferred to have formed by flattening and vertical flow in response to east-west compression. Deformation is interpreted to represent the response of a preexisting lithospheric boundary to compressive stresses related to subduction of material to the west.
", "doi": "10.7907/JP15-KC07", "publication_date": "1988", "thesis_type": "phd", "thesis_year": "1988" }, { "id": "thesis:7484", "collection": "thesis", "collection_id": "7484", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02202013-103037890", "primary_object_url": { "basename": "Rudy 1987.pdf", "content": "final", "filesize": 28898031, "license": "other", "mime_type": "application/pdf", "url": "/7484/1/Rudy 1987.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Mars: High Resolution VLA Observations at Wavelengths of 2 and 6 cm and Derived Properties", "author": [ { "family_name": "Rudy", "given_name": "Donald James", "clpid": "Rudy-Donald-James" } ], "thesis_advisor": [ { "family_name": "Ingersoll", "given_name": "Andrew P.", "clpid": "Ingersoll-A-P" } ], "thesis_committee": [ { "family_name": "Ingersoll", "given_name": "Andrew P.", "clpid": "Ingersoll-A-P" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Goldreich", "given_name": "Peter Martin", "clpid": "Goldreich-P-M" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Muhleman", "given_name": "Duane Owen", "clpid": "Muhleman-D-O" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_gps" } ], "abstract": "Observations of Mars at wavelengths of 2 and 6cm were made using the VLA in its A configuration. Two seasons were observed; late spring in the northern hemisphere (LS ~ 60\u00b0) and early summer in the southern summer (LS ~ 300\u00b0). The sub-earth latitudes were 25\u00b0N and 25\u00b0S, for each of these seasons respectively. So the geometry for viewing the polar region was optimal in each case. Whole-disk brightness temperatures were estimated to be 193.2 K \u00b1 1.0 at 2 cm and 191.2 K \u00b1 0.6 at 6 cm for the northern data set and 202.2 K \u00b1 l.0 at 2 cm and 195.4 K \u00b1 0.6 at 6 cm for the southern data set (formal errors only). Since measurements of the polarized flux were taken at the same time, whole-disk effective dielectric constants could be estimated and from these, estimates of sub-surface densities could be made. The results of these calculations at 2cm yielded whole-disk effective dielectric constants of 2.34 \u00b1 0.05 and 2.02 \u00b1 0.03 which imply sub-surface densities of 1.24 g cm-3 \u00b1 0.06 and 1.02 g cm-3 \u00b1 0.05 for the north and south, respectively. The same calculations at 6 cm yielded effective densities of 1.45 g cm-3 \u00b1 0.10 and 1.31 g cm-3 \u00b1 0.07 from effective dielectric constants of 2.70 \u00b1 0.09 and 2.48 \u00b1 0.06 for the north and south data sets, respectively.
\r\n\r\nFrom the mapped data these parameters were also estimated as a function of latitude between latitudes of 15\u00b0S and 60\u00b0N for the north data set; and between latitudes of 30\u00b0N and 60\u00b0S for the south data set. A region in which the brightness temperature behaves in an anomalous manner was discovered in both data sets. This region lies between about 10\u00b0S and 40\u00b0S. Here the brightness temperatures at both wavelengths in both data sets appears lower, by 4 K to 8 K, than a nominal model would predict. In addition to the effective dielectric constant and sub-surface density the radio absorption length of the sub-surface was estimated. The radio absorption length for most of these latitudes was about 15 wavelengths with formal errors on the order of 5 or 10 wavelengths. This is true for both data sets. The estimation of the effective dielectric constant at most latitudes was between 2 and 3.5 with only slight differences between the two different wavelengths. The two data sets show the same relative trends, but are off by a scaling factor.
\r\n\r\nThese estimates of the dielectric constant lead to estimation of the sub-surface densities as a function of latitude. Most calculations of the sub-surface density yielded results between 1 and 2 g cm-3 with errors on the order of 0.5 g cm-3. These results seem to imply that the sub-surface is not much different than the surface as observed by the Viking and Mariner missions. In line with this, an examination of the correlation of the dielectric constant at each wavelength with the thermal inertia, determined by the Viking infrared measurements, shows a relatively strong correlation, at both wavelengths, for the North data set. The South data set, however, shows little to nocorrelation between the radio parameters and the thermal inertia. Since the South data set is primarily composed of latitudes which contain the anomalous region, it is not suprising that the South data set shows no correlation.
\r\n\r\nIn addition, the thermal-radiative model used to estimate the above parameters was used to estimate the variability of the whole-disk brightness temperature of Mars. This was done in an effort to establish a background for those astronomers wishing to use Mars as a calibration source. The parameters investigated for their effect on the whole-disk brightness temperature of Mars were: the sub-earth longitude, the sub-earth latitude, the sub-earth time of day, the dielectric constant, and the radio absorption length. A nominal model was first created which established the variation of the brightness temperature as a function of season and radio absorption length. A nominal value of 2.2 was used for the dielectric constant, and the sub-earth latitude was set at 0\u00b0N and the sub-earth longitude was set at 75\u00b0W. The sub-earth time of day was held at noon for this nominal model. This is equivalent to a 0\u00b0 phase angle. The most important geometric factor was the sub-earth latitude. The error in estimating the whole-disk brightness temperature of Mars by using the wrong sub-earth latitude can be as large as 5 to 10%. The charts presented will be useful to estimate the whole-disk brightness temperature which the thermal model would predict. It is believed that the error in this estimate is less than or equal to 5 K.
\r\n", "doi": "10.7907/3g59-p796", "publication_date": "1987", "thesis_type": "phd", "thesis_year": "1987" }, { "id": "thesis:2961", "collection": "thesis", "collection_id": "2961", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-07212008-101544", "primary_object_url": { "basename": "Sams_db_1986.pdf", "content": "final", "filesize": 27627137, "license": "other", "mime_type": "application/pdf", "url": "/2961/1/Sams_db_1986.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "U/Pb Zircon Geochronology, Petrology, and Structural Geology of the Crystalline Rocks of the Southernmost Sierra Nevada and Tehachapi Mountains, Kern County, California", "author": [ { "family_name": "Sams", "given_name": "David Bruce", "clpid": "Sams-David-Bruce" } ], "thesis_advisor": [ { "family_name": "Saleeby", "given_name": "Jason B.", "clpid": "Saleeby-J-B" } ], "thesis_committee": [ { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" }, { "family_name": "Saleeby", "given_name": "Jason B.", "clpid": "Saleeby-J-B" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" }, { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "Field mapping, petrography, U/Pb zircon geochronology, and Rb/Sr geo-chemistry on the crystalline rocks of the southernmost Sierra Nevada and Tehachapi Mountains north of the Garlock fault have 1) generated a structural, geo-chemical, and geochronological framework; 2) demonstrated a continuation of Sierran plutonic and metasedimentary rocks into the Tehachapi Mountains; 3) indicated that the region, in particular the gneiss complex of the Tehachapi Mountains, represents the deepest exposed levels of the Sierra Nevada batholith; 4) placed constraints on possible mixing models between upper mantle and meta-sedimentary components to generate the observed geochemical signatures of the rocks; and 5) resolved a major mid-Cretaceous deformation event.
\r\n\r\nThe main crystalline rocks of the study area are the rocks of the Bear Valley Springs intrusive suite and the gneiss complex of the Tehachapi Mountains. The Bear Valley Springs suite is a mid-Cretaceous tonalite batholith complex with coeval gabbroic intrusives. The gneiss complex of the Tehachapi Mountains consists dominantly of early-Cretaceous orthogneiss, with subordinate paragneiss and local domains having granulite affinities. The orthogneisses are dominantly tonalitic in composition, with significant layers and domains of granodioritic to granitic and lesser dioritic to gabbroic gneiss. Quartz-rich metasedimentary rocks and marble constitute the main framework assemblage into which the plutonic rocks were emplaced. Field relations demonstrate assimilation of metasedimentary material into the orthogneisses and magma mixing between mafic, tonalitic, and anatectic granitic material derived from the metasediments.
\r\n\r\nCrystalline rocks of the region, with the exception of metasedimentary framework rocks, fall into a narrow age range of 90-120 Ma, and exhibit three main age suites. Most samples have zircon populations with systematics indicative of igneous crystallization, with signs of zircon inheritance or entrainment in the vicinity of metamorphic septa. Strongly discordant samples are relatively rare, and include the granodiorite of Claraville (concordia intercepts of 90/1900 Ma), the paragneiss of Comanche Point (108/1450), and a quartzite in the Kings sequence metasedimentary framework rocks (1700 Ma upper intercept).
\r\n\r\nThe rocks in the first age suite (gneiss complex of the Tehachapi Mountains and augen gneiss of Tweedy Creek) exhibit a greater degree of deformation, especially under moderate to high grade conditions. Major deformational fabrics are expressed as gneissic banding, mylonitization, recrystallization, boudinaging, and transposition of internal contacts. Internally and externally concordant zircon systematics of the orthogneisses in this suite indicate igneous crystallization between 110-120 Ma. Discordant zircon systematics suggest entrainment of minor amounts of mid-Proterozoic zircon and/or open system lead loss in response to the 100 Ma magmatic culmination (Bear Valley Springs event).
\r\n\r\nThe second suite, 100\u00b12 Ma Bear Valley Springs intrusive suite (tonalite of Mount Adelaide, tonalite of Bear Valley Springs, hypersthene tonalite of Bison Peak, and metagabbro of Tunis Creek) contains igneous rocks which locally cross-cut the older suite. These rocks have a late-stage deformational fabric shown primarily in the tonalites as pervasive foliation and faint gneissic banding. The zircon systematics of this suite are internally and externally concordant, indicating igneous crystallization ages, with only local evidence of entrainment of mid-Proterozoic zircon. The deformation of the suite was synplutonic, with later phases within the suite lacking significant deformational fabrics. The major deformational fabrics exhibited in the Tehachapi and Bear Valley Springs suites may be the result of the intrusion of the tonalite batholith into the lower crust, and/or the result of intra-arc shearing that was preferentially concentrated in various intrusive bodies.
\r\n\r\nThe third suite, late deformational intrusive rocks, consists of units which cross-cut deformational features in both the older suites. These youngest rocks are themselves slightly to nondeformed. The members in the suite have ages of 90 Ma (granodiorite of Claraville), 93 Ma (tonalite stock at Tweedy Creek), and 94 Ma (pegmatite dike at Comanche Point).
\r\n\r\nField mapping and petrography have shown a southward continuation of Sierran plutonic and metasedimentary framework rocks to the region of Tejon Creek. The plutons show a constant age spread and overall composition throughout the region, with a greater degree of solidus to hot sub-solidus deformation exhibited southward. The metamorphic septa have a higher grade, and are more strongly deformed southwards, becoming migmatitic. The southern margin of the tonalite of Bear Valley Springs consists of a gradational contact with the hypersthene tonalite of Bison Peak, which is believed to represent the floor or conduit phase of the batholith. Along its southwestern margin, the tonalite of Bear Valley Springs grades into the gneiss complex of the Tehachapi Mountains through a region of tonalitic gneiss that appears to be derived through the mixing of tonalitic magmas and migmatitic melts produced from paragneiss components in the gneiss complex. Paleomagnetic and structural restoration of the southwestern margin of the tonalite indicates that it may represent the uptilted floor of the batholith that originally spread out over its gneissic substrate.
\r\n\r\nThe crystalline rocks of the southernmost Sierra Nevada represent the deepest exposed levels of the Sierra Nevada batholith. Saleeby and others (1986a) indicate a continual increase in depth of exposure from the central to southern part of the batholith. Elan (1985) shows metamorphic conditions of 3.0 kb and 700\u00b0C in the south-central Sierras, while Sharry (1981b) has suggested that parts of the gneiss complex have a deep-seated (8 kb) origin with rapid late-Cretaceous uplift. Granulitic nodules of similar character to parts of the gneiss complex have been described by Domenick and others (1983) as originating from a similar depth beneath the central Sierra. Gneissic granitoids have numerous lenses of mafic to ultramafic cumulates showing igneous crystallization under granulite facies conditions. The domains of \"granulite\" in the gneiss complex of the Tehachapi Mountains are believed to be hot, relatively dry zones in a crystallizing and deforming batholithic complex. Magmatic epidote-bearing tonalites and late stage sub-solidus autometamorphic garnet growth are further indicators of a deep (\u22656 kb) level of origin for the region.
\r\n\r\nThe \"granulites\" (metagabbro of Tunis Creek and hypersthene tonalite of Bison Peak) are interpreted to be of an igneous origin. Evidence for this interpretation consists of: relict olivine grains and cumulate textures; foliation believed to be the result of igneous flow; zoned plagioclase necessitating the presence of a magma; tonalites that contain epidote that is interpreted to be of magmatic origin; \u03b418O and Rb/Sr isotopic values in the igneous range; abundance of retro-grade but paucity of prograde mineral reactions; gradational contacts between plutonic units; and observed intrusive contacts. Pyroxene within the \"granulites\" is believed to be of a pyrogenic origin. The rocks typically have a retrograde assemblage that consists of olivine \u2192 orthopyroxene and pyroxene \u2192 amphibole. The mineral assemblages all point to a downward P-T path.
\r\n\r\nSimple two-component mixing models have been constructed for samples from the southernmost Sierra Nevada, and involve incorporation of partial to complete melts of metasedimentary material into \"primitive\" upper mantle orogenic mafic magmas prior to crystallization. The two possible end-members are the quartzite-paragneiss of Comanche Point and the hypersthene tonalite of Bison Peak-metagabbro of Tunis Creek. Initial 87Sr/86Sr correlates directly with \u03b418O, and generally correlates inversely with Sr content for most of the samples. Simple isotopic mixing models indicate incorporation of up to 33% metasedimentary material in the granitic rocks, and up to 15% in the tonalites, with younger and more easterly samples requiring a larger metasedimentary component. The non-correlation of Sro with Sr content for some of the Pastoria Creek samples indicates an oceanic-affinity source with little interaction with continental crustal material. A number of samples appear to require a third, probable lower continental crustal and/or oceanic crustal-upper mantle component that may have a Paleozoic age.
\r\n\r\nBased on Rb/Sr and K/Ar age systematics, the region was uplifted in a regional cooling event at ~85 Ma perhaps as part of regional thrusting event(s) in southern California. The crystalline rocks were subsequently exposed and unconformably overlapped by Eocene marine sediments. Paleomagnetic data suggest about 45-60\u00b0 of clockwise rotation between 80 and 16 Ma for the southern end of the Sierras, possibly as the result of the thrusting event responsible for the regional uplift.
\r\n\r\nSaleeby and others (1986c) have suggested that the lower crust beneath the Sierra Nevada batholith is comprised in part by granulitic and mafic intrusive rocks. Experimental studies by Christensen and Fountain (1975) also suggest the presence of granulites in the lower continental crust. The interpretation that the study area represents the deepest exposed level of the southernmost Sierra Nevada batholith leads to the implication that granulitic-affinity rocks comprise the lower part of the continental crust. Therefore, this study provides some degree of confirmation to the aforementioned hypotheses.
\r\n", "doi": "10.7907/C883-H765", "publication_date": "1986", "thesis_type": "phd", "thesis_year": "1986" }, { "id": "thesis:2734", "collection": "thesis", "collection_id": "2734", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06262006-133025", "primary_object_url": { "basename": "VanZyl_jj_1986.pdf", "content": "final", "filesize": 7972149, "license": "other", "mime_type": "application/pdf", "url": "/2734/1/VanZyl_jj_1986.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "On the Importance of Polarization in Radar Scattering Problems", "author": [ { "family_name": "van Zyl", "given_name": "Jakob Johannes", "clpid": "van-Zyl-Jakob-Johannes" } ], "thesis_advisor": [ { "family_name": "Papas", "given_name": "Charles Herach", "clpid": "Papas-C-H" } ], "thesis_committee": [ { "family_name": "Papas", "given_name": "Charles Herach", "clpid": "Papas-C-H" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Elachi", "given_name": "Charles", "orcid": "009-0002-2156-967X", "clpid": "Elachi-C" }, { "family_name": "Posner", "given_name": "Edward C.", "clpid": "Posner-E-C" }, { "family_name": "Psaltis", "given_name": "Demetri", "orcid": "0000-0003-4684-8800", "clpid": "Psaltis-D" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In this thesis, the importance of polarization in radar scattering problems is investigated. The different matrix characterizations of scatterers are discussed in detail. The problem of finding the polarizations which would yield an optimum amount of power received from the scatterer is solved for the most general case. This shows that for certain classes of scatterers six optimum polarizations exist. The concept of a polarization spectrum to characterize a scatterer is introduced. The usefulness of these spectrums is illustrated when results, using measured multipolarization synthetic aperture radar data, are discussed. Another useful parameter, the coefficient of variation, is introduced. Measured results show that this parameter may be used to form an idea of the scale over which the scattering properties of the scene being imaged vary. The problem of finding the effective scattering operator of a slab filled with different scatterers is formulated. Detailed expressions are given for the effective single scattering operators. This formulation is illustrated by calculating the effective single scattering operators for models of different types of vegetation.
", "doi": "10.7907/QRD0-YE09", "publication_date": "1986", "thesis_type": "phd", "thesis_year": "1986" }, { "id": "thesis:3283", "collection": "thesis", "collection_id": "3283", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08302006-135307", "primary_object_url": { "basename": "Weldon_rj_1986.pdf", "content": "final", "filesize": 19393034, "license": "other", "mime_type": "application/pdf", "url": "/3283/1/Weldon_rj_1986.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "The Late Cenozoic Geology of Cajon Pass; Implications for Tectonics and Sedimentation along the San Andreas Fault", "author": [ { "family_name": "Weldon", "given_name": "Ray James, II", "clpid": "Weldon-Ray-James-II" } ], "thesis_advisor": [ { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" } ], "thesis_committee": [ { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" }, { "family_name": "Kirschvink", "given_name": "Joseph L.", "orcid": "0000-0001-9486-6689", "clpid": "Kirschvink-J-L" }, { "family_name": "Sieh", "given_name": "Kerry E.", "orcid": "0000-0002-7311-2447", "clpid": "Sieh-K-E" }, { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "The geology in Cajon Pass, southern California, provides a detailed record of strike slip activity on the San Andreas fault, compressional deformation associated with the uplift of the central Transverse Ranges and an excellent Cenozoic record of syntectonic sedimentation. Age control was established in all of the sediments deposited since the late Early Miocene, using biostratigraphy, magnetostratigraphy, fission-track dating of volcanic ashes, radiocarbon dating, soil development, and the relative stratigraphic and geomorphic position of the units. Tectonic deformation and sedimentation styles varied through time, reflecting the evolution of the San Andreas fault zone within the Pacific - North American plate boundary. Particular attention was paid to determining rates of tectonic deformation and establishing the timing of changes in deformational and depositional styles in the area.
\r\n\r\nProgressive offset of radiocarbon-dated alluvial and paludal sediments have been used to determine the Holocene slip rate on the San Andreas fault in Cajon Pass. Four independent measurements of the slip rate yield an average of 24.5 \u00b1 3.5 mm/yr. The similarity of the four values, which span different intervals of time up to 14,400 years ago, suggest that the slip rate has been constant during this period.
\r\n\r\nAn excavation across the San Andreas fault provided some constraints on the timing of paleoearthquakes. Coupled with the historic record, this investigation indicates that the last earthquake associated with rupture on the fault in Cajon Pass occurred around 1700 AD. At least 2 earthquakes caused rupture on the San Andreas fault after 1290 AD and perhaps 6 earthquakes are recorded in the thousand year period before European settlement of southern California in the 1770s.
\r\n\r\nDowncutting and erosion into the western San Bernardino Mountains, during the last 700,000 years, has created Cajon Pass as it exists today. The downcutting was punctuated by at least four pulses of channel aggradation that provide stratigraphic markers throughout the area. They are dated at 0.5 \u00b1 0.1 million, 55,000 \u00b1 10,000, 17,000 to 6,000, and 2000 to 300 years ago. These aggradational periods were caused by order of magnitude increases in sediment production associated with changes in the climate from relatively wet to dry conditions.
\r\n\r\nThe locus of the latest Pleistocene to early Holocene fill migrated upstream through time, with aggradation lasting only a few thousand years at any point in the drainage. Incision of the fill also migrated upstream, beginning long before the fill pulse reached the headwaters of the system. The fill terrace, or upper surface of the fill deposit, does not represent a time line or a surface down which water flowed everywhere at once. Thus, the use of a fill terrace as either a time or spacial reference line for tectonic studies, without accounting for the its transgressive character, can result in erroneous conclusions.
\r\n\r\nDuring the early to middle Pleistocene, prior to the erosion of Cajon Pass, the southern part of the area was uplifted and coarse fan deposits were shed across the northern part of the area onto the Mojave Desert. Some of these sediments were derived from distinctive sources in the San Gabriel Mountains southwest of the San Andreas fault zone. Matching these distinctive facies in the deposits with their sources established offsets across the fault zone and made it possible to tie the uplift northeast of the fault to activity on the San Jacinto fault as it passed by across the San Andreas fault. The fan deposits are dated by a combination of bio-stratigraphy and magnetostratigraphy.
\r\n\r\nThe average slip rate across the combined San Andreas and San Jacinto faults is 37.5 \u00b1 2 mm/yr during the Quaternary Period. The six determinations of the slip rate show no evidence for rate changes during the Quaternary Period. The slip rate on the San Andreas fault alone was determined by one offset of be 21 \u00b1 7 mm/yr. The record of contemporaneous activity on the San Jacinto fault to the southeast requires that the San Andreas fault's rate be close to the upper limit of this range.
\r\n\r\nContemporaneous activity on the San Andreas and San Jacinto faults is uplifting the high, eastern San Gabriel Mountains and deforming the San Andreas fault plane. The geometry of this deformation is such that uplift of the country on the northeast side of the San Andreas fault occurs. This hypothesis is supported by the northwest migration of the uplift at the slip rate on the San Andreas fault, and the style of surface deformation that is characteristic of folding over a steeply dipping lateral ramp at depth.
\r\n\r\nA kinematic model was constructed to determine the role of the San Andreas fault in the Pacific - North American plate boundary. The Quaternary slip rates determined for the San Andreas fault in Cajon Pass and the slip vectors associated with the geometry of the fault zone were combined with an assumption of rigid block motion away from the faults and published slip rates for the other major faults in southern California. The model produces internally consistent motions for all of the blocks. Vector sums of the slip rate across the Pacific - North American boundary yield only the relative plate motion if the path includes the western Transverse Ranges. The model solution indicates that the western Transverse Ranges are not part of the San Andreas system but are a left-step in a separate coastal system that currently accommodates about 1/3 of the Pacific - North American plate motion.
\r\n\r\nThe southeastern San Bernardino Mountains are being uplifted because of a left step in the arcuate trace of the San Andreas fault. The western San Bernardino Mountains and the eastern San Gabriel Mountains are being uplifted by the deformation associated with the junction of the San Andreas and San Jacinto faults. Because the convergence in this area can be explained by local geometry, it is clear that southern California cannot be part of the Pacific plate, colliding at the plate rate into North America across the Transverse Ranges. Instead, southern California appears to be a sliver between the San Andreas system and the coastal system, and is rotating counterclockwise as it translates northwest, transferring the convergence to the coastal system.
\r\n\r\nThe middle to late Quaternary uplift of the Cajon Pass area was the culmination of the uplift of the San Bernardino Mountains that began in the Miocene. Three distinct phases of uplift have been recognized, suggesting a long-term interaction between the strike-slip activity on the San Andreas system and the compressional tectonics of the Transverse Ranges. The San Bernardino Mountains began to take shape following a pervasive earliest Miocene unconformity. Broad, homogeneous basins, separated by mature uplands of moderate to low relief developed across the southwest-draining regional paleoslope. The earliest activity on the San Andreas fault is believed to be associated with this early extensional phase.
\r\n\r\nLate Miocene to early Pliocene, south-directed thrusting uplifted the \"proto\" San Bernardino Mountains, creating steep, south-facing relief along the San Andreas. During this time the San Gabriel fault was the most (and perhaps only) active trace of the San Andreas system. Thrusting stopped as the San Andreas fault became active again, probably coincident with the beginning of the opening of the Gulf of California, 5 million years ago. Pliocene and earliest Pleistocene sedimentation took place in narrow east-west trending, structurally controlled basins created by the Mio-Pliocene thrusting.
\r\n\r\nEarly to middle Pleistocene, north-directed thrusting across a shallow, south-dipping ramp uplifted the broad central plateau of the San Bernardino Mountains, and created the North Frontal fault system. During the middle and late Quaternary, this activity was largely replaced by south-directed thrusting and lateral ramping on steep, north-dipping planes along the San Andreas fault. This activity produced the tremendous relief and regionally-extensive north-dipping structural blocks in the San Gorgonio and Cajon Pass areas, and continues today. The structures and geomorphology of the range reflects its varied history; different parts of the range are as old as late Early Miocene and as young as the Holocene.
\r\n\r\nAll three phases of uplift appear to be related to the southern Big Bend in the San Andreas fault system, which has existed since the Miocene. Contemporaneous and alternating periods of thrusting and strike-slip activity has created bedrock \"flaps\", displaced fault slivers and strand switching that are responsible for the complex geology associated with San Andreas fault through the Transverse Ranges. Recognition of these features with detailed field work will greatly expand our knowledge of the tectonics and seismic hazards associated with the San Andreas system in southern California.
", "doi": "10.7907/9WJY-2A97", "publication_date": "1986", "thesis_type": "phd", "thesis_year": "1986" }, { "id": "thesis:1307", "collection": "thesis", "collection_id": "1307", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-04082005-133814", "primary_object_url": { "basename": "Mattson_sm_1985.pdf", "content": "final", "filesize": 5745993, "license": "other", "mime_type": "application/pdf", "url": "/1307/1/Mattson_sm_1985.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Optical Expressions of Ion-Pair Interactions in Minerals", "author": [ { "family_name": "Mattson", "given_name": "Stephanie Margaret", "clpid": "Mattson-Stephanie-Margaret" } ], "thesis_advisor": [ { "family_name": "Stolper", "given_name": "Edward M.", "orcid": "0000-0001-8008-8804", "clpid": "Stolper-E-M" } ], "thesis_committee": [ { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Kamb", "given_name": "W. Barclay", "clpid": "Kamb-W-B" }, { "family_name": "Rossman", "given_name": "George Robert", "orcid": "0000-0002-4571-6884", "clpid": "Rossman-G-R" }, { "family_name": "Stolper", "given_name": "Edward M.", "orcid": "0000-0001-8008-8804", "clpid": "Stolper-E-M" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "Clusters of transition element cations in neighboring sites frequently govern the optical properties of minerals. This is particularly true of Fe-bearing minerals which may exhibit several types of ion-pair transitions. In this thesis four different types of interactions were distinguished: intensified spin-forbidden transitions of Fe3+ clusters, intensified Fe2+ spin-allowed transitions of Fe2+-Fe3+ clusters, heteronuclear charge transfer transitions of Fe2+-Ti4+ and Mn2+-Ti4+ clusters, and homonuclear charge transfer transitions of Fe2+-Fe3+ clusters.
\r\n\r\nThe optical characteristics of Fe3+ in red Fe3+ rich and black Fe3+,Fe2+-rich tourmalines were examined by absorption spectroscopy in the visible and near-infrared, M\u00f6ssbauer spectroscopy and magnetic susceptibility measurements. Intense optical absorption features at 485 and 540 nm were assigned to transitions of exchange-couple Fe3+ pairs in two different site combinations. Absorption spectra at variable temperatures and of samples which were oxidized and reduced were used to establish these assignments. Site assignments were based on intensity ratios in different polarizations according to the polarization of these transitions along the vector between the interacting cations. The 485 nm band occurs at an unusually low energy for Fe3+ in silicate minerals. Similar behavior was observed in the spectrum of coalingite, a Mg,Fe-hydroxy carbonate, and has been proposed to result from magnetic exchange in large, edge-shared octahedra. The antiferromagnetic exchange which is generally associated with intensity increases in Fe3+ clusters was confirmed by variable temperature magnetic susceptibility measurements. The M\u00f6ssbauer spectrum of a red tourmaline with 3.4% Fe exhibits an unusual decrease in width of peaks by ~30% from 298 K to 5 K which may be related to an unusual interaction between Fe3+ and trace amounts of Fe2+.
\r\n\r\nOptical absorption and M\u00f6ssbauer studies of Fe2+-bearing tourmalines with variable Fe3+ contents were used to examine Fe2+ transitions which are intensified through an interaction with Fe3+ neighbors. The variation of molar absorptivity of Fe2+ bands with the fraction of Fe2+ in Fe2+-Fe3+ pairs indicates that Fe3+ ions increase the absorptivity of Fe2+ bands to ~1200 M-1cm-1 as compared to ~5 M-1cm-1 for non-interacting Fe2+. Approximately equal degrees of intensification were observed for both components of the 5T2 \u2192 5E Fe2+ transition as well as for Fe2+ in two different sites. Although the detailed behavior of non-interacting Fe2+ ions differ in Mg-tourmalines and Li,Al-tourmalines, the characteristics of Fe2+-Fe3+ absorption are constant. Intensity increases were restricted to the polarization which coincided with the vector between the Fe2+ and Fe3+ ions. The intensified Fe2+ transitions are characterized by an unusual temperature response. The integrated intensity of these transitions increases by 10-50% at 83 K as compared to 296 K. The positions and widths of the intensified transitions maintain the values of the non-interacting Fe2+. Tourmalines with the lowest Fe3+ contents were the gemmy Li,Al-tourmalines which generally form in pockets within pegmatites. Fe,Mg-tourmalines exhibited consistently higher Fe3+ contents than any of the Li-bearing tourmalines examined. Oxidation of Fe2+ which resulted from gamma irradiation of blue Li-tourmalines which contained several percent each of MnO and FeO could be monitored by increases in Fe2+ intensity in one polarization.
\r\n\r\nFe2+-Ti4+ charge transfer transitions were examined in minerals which contain stoichiometric quantities of Fe and Ti -- taramellite, neptunite, and traskite -- and tourmaline. The wavelength of these transitions ranged between 400 and 500 nm, and the halfwidths ranged between 7000 and 9000 cm-1. These characteristics can generally be used to assign Fe2+-Ti4+ charge transfer transitions. The molar absorpitivities of these transitions, however, exhibit very large variations. The molar absorptivity of Fe2+-Ti4+ charge transfer in neptunite is ~225 M-1cm-1 in beta polarization, in taramellite it is ~1300 M-1cm-1 and in tourmaline it is ~4000 M-1cm-1. Tentative assignments of Fe2+-Ti4+ in more dilute minerals generally compare favorably with the energy and width stated above. However, sapphire and other Al-minerals such as kyanite have very different characteristics for bands assigned to Fe2+-Ti4+ charge transfer. The Fe2+-Ti4+ charge transfer transition in taramellite exhibits no change in integrated intensity with decreasing temperature but increases by 15% from 296 K to 83 K in tourmaline. Mn2+-Ti4+ charge transfer was also assigned to a transition at 320 nm in two unusual yellow tourmalines.
\r\n\r\nThe characteristics of Fe2+-Fe3+ charge transfer transitions were reviewed in light of recent data and with regard to their utility as diagnostic criteria. A correlation between charge transfer energy and the separation of the interacting cations proposed by Smith and Strens (1976) could not be supported by the expanded data base. Temperature variations of charge transfer transition areas were also examined. The magnetic behavior of two minerals which exhibited different temperature responses were investigated. General agreement with the theories of Cox (1980) and Girered (1983) that suggest that ferromagnetic exchange should produce intensity increases at low temperature and that antiferromagnetic exchange produces intensity decreases was confirmed by these examples of Fe2+-Fe3+ charge transfer but could not explain the temperature response of Fe2+-Ti4+ charge transfer transitions. In any case, an increase in intensity with decreasing temperature, which is generally expected on the basis of experimental observations, cannot be used in a negative sense to eliminate a charge transfer assignment. The large width of charge transfer transitions is generally the most useful diagnostic criterion.
\r\n\r\nCox, PA (1980) Electron transfer between exchange-coupled ions in a mixed-valency compound. Chem Phys Lett 69: 340-343
\r\n\r\nGirerd, J-J (1983) Electron transfer between magnetic ions in mixed valence binuclear systems. J Chem Phys 79: 1766-1775
\r\n\r\nSmith, G and Strens, RGJ (1976) Intervalence transfer absorption in some silicate, oxide and phosphate minerals. In: The Phyics and Chemistry of Minerals and Rocks, Strens, RGJ (ed.). New York: Wiley and Sons, pp. 583-612
", "doi": "10.7907/acn3-nr54", "publication_date": "1985", "thesis_type": "phd", "thesis_year": "1985" }, { "id": "thesis:282", "collection": "thesis", "collection_id": "282", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01222009-094629", "primary_object_url": { "basename": "Meisling_ke_1984.pdf", "content": "final", "filesize": 18120165, "license": "other", "mime_type": "application/pdf", "url": "/282/1/Meisling_ke_1984.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Neotectonics of the North Frontal Fault System of the San Bernardino Mountains, Southern California: Cajon Pass to Lucerne Valley", "author": [ { "family_name": "Meisling", "given_name": "Kristian Erik", "clpid": "Meisling-Kristian-Erik" } ], "thesis_advisor": [ { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" } ], "thesis_committee": [ { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Kirschvink", "given_name": "Joseph L.", "orcid": "0000-0001-9486-6689", "clpid": "Kirschvink-J-L" }, { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "The north frontal fault system of the San Bernardino Mountains is made up of a number of disparate structural elements, each of which accommodates range-front deformation in a manner dictated by its geometry. A two-stage history of late Cenozoic structural development is proposed for the northwestern San Bernardino Mountains: the range was first uplifted on low-angle structures and later modified by high-angle faulting. Evidence for Pliocene onset of deformation and uplift in the westernmost San Bernardino Mountains is found in the provenance and character of the associated sediments.
\r\n\r\nThrusting uplifted the northern range front during a pulse of deformation spanning late Pliocene through middle Pleistocene time. Uplift in the westernmost San Bernardino Mountains was accomplished contemporaneously by tilting, warping, and arching. Nature and timing of deformation are consistent with the hypothesized formation of a transpressional welt across the San Andreas fault, which may have affected both the San Bernardino and San Gabriel Mountains.
\r\n\r\nHigh-angle faulting replaced thrusting and warping as the dominant style of deformation in the northwestern San Bernardino Mountains beginning in middle to late Pleistocene time. Pleistocene left-lateral faulting in the westernmost San Bernardino Mountains has accomplished north-south crustal shortening by squeezing the San Bernardino Mountains block eastward. Northwest-trending right-lateral faults, characteristic of the Mojave block prior to range-front uplift, have reasserted and incorporated themselves in the complex zone of range-front deformation. Local extension resulting in minor graben formation, appears to have been associated with lateral motion on the north frontal fault zone in Fifteenmile Valley (Sky Hi Ranch fault zone) and the Cleghorn fault zone.
\r\n\r\nArcuate patterns of faulting in the western San Bernardino Mountains can be explained in terms of the pattern of faulting predicted for secondary faults near the end of a strike-slip fault. In this case the \"end effect\" would be produced by a change in slip rate on the San Andreas fault in Cajon Pass, possibly related to motion on the San Jacinto fault. All faulting in the study area is interpreted as the product of compression across the San Andreas fault.
\r\n\r\nA weathered erosion surface was developed on the crystalline terrane over most of the area in response to humid conditions during the late Miocene(?), at which time the region was characterized by an upland surface of subdued relief. This weathered erosion surface is a useful index to structural deformation in the northwestern San Bernardino Mountains.
\r\n\r\nLate Cenozoic stratigraphy constrains the timing of deformation and uplift in the northwestern San Bernardino Mountains. The late Miocene to Pliocene(?) Crowder Formation was deposited by drainages carrying distinctive volcanic and metamorphic clasts from the Victorville area southward, across the site of the western San Bernardino Mountains. The late Miocene beds of the Punchbowl Formation are faulted against the lower Crowder Formation, but are overlain by the upper Crowder Formation. The Punchbowl and Crowder Formations share the same age and paleocurrent direction, yet differ markedly in sediment character and provenance. The relationship between these two units remains an unsolved stratigraphic problem, which seemingly requires substantial lateral structural translation.
\r\n\r\nThe middle to late Pliocene onset of deformation and uplift is recorded in the stratigraphic sequence by the appearance of fine-grained sediments, new clast lithologies, and northerly paleocurrent directions. The volcanogenic eastern facies of the Crowder(?) Formation is believed to be a syntectonic deposit indicative of ponding that accompanied the reversal in drainage direction brought on by incipient uplift of the western San Bernardino Mountains. The fine grained, lacustrine character of the Harold Formation can be interpreted in the same way; the base of the Harold Formation is < 2.75 my old on the basis of paleomagnetic constraints. The Old Woman Sandstone in Lucerne Valley records an abrupt change from fine-grained sediments indicative of incipient uplift to coarse, angular debris signalling the emergence of the range front as a topographic element. The influx of range-front debris is estimated to have occurred < 2.5 my ago. Several small, deformed patches of fine-grained sediment in Arrastre Canyon appear to be of similar origin.
\r\n\r\nThe Quaternary stratigraphy of the western San Bernardino is dominated by the Harold Formation, Shoemaker Gravel and Older Alluvium, which underlie the Victorville Fan. These units were shed northeast off the San Gabriel and western San Bernardino Mountains, and record their uplift. The Harold Formation contains the earliest appearance of San Gabriel Mountains crystalline basement lithology within the stratigraphy of the Mojave block. The Victorville Fan sequence is believed to be time-transgressive, reflecting the northwestward movement of the San Gabriel Mountains crystalline terrane along the San Andreas fault.
\r\n\r\nThe Older Alluvium capping the Shoemaker Gravel in Cajon Pass records the Brunhes/Matuyama polarity reversal of 730,000 y B.P. The Older Alluvium can be divided into dissected and undissected facies believed to predate and postdate the polarity transition respectively. This crude chronology can be extended to sediments on the flanks of the Ord Mountains that define a late Pleistocene drainage system tributary to the ancestral Mojave River. The Pleistocene units contain evidence of progressive growth and integration of drainage in the Western San Bernardino Mountains in response to uplift during Pleistocene time.
\r\n\r\nDetailed geologic mapping of the northwestern San Bernardino Mountains permits slip rates and offsets to be calculated for important range-front faults. The Cleghorn fault has a cumulative left-lateral offset of 3.5 to 4.0 kilometers, and a slip rate of about 3.0 mm/yr. The Sky Hi Ranch fault zone has a late Pleistocene right-lateral offset of approximately 0.5 kilometers, with a slip-rate on the order of 1 mm/yr. The faults along the west flank of the Ord Mountains have a vertical slip-rate of less than 1 mm/yr.
\r\n\r\nThe Cleghorn fault is classified as \"active\", under the criteria set forth by the State of California in the Alquist-Priolo Act of 1972, and is considered capable of a Ms 6.8 earthquake. Parts of the north frontal fault system on the west flank of the Ord Mountains and the Sky Hi Ranch fault zone are classified as \"potentially active\", in the terminology of the Alquist-Priolo Act, and are thought to be capable of a Ms 6.6 to 6.8 event. The Tunnel Ridge lineament and Arrastre Canyon Narrows fault zones are considered tentatively active, and should be examined in detail prior to development of adjoining areas. Clearly, the San Andreas fault poses the greatest seismic hazard to the communities in the study area.
", "doi": "10.7907/RSDP-BS67", "publication_date": "1984", "thesis_type": "phd", "thesis_year": "1984" }, { "id": "thesis:2981", "collection": "thesis", "collection_id": "2981", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-07252007-135803", "primary_object_url": { "basename": "Powell_re_1981.pdf", "content": "final", "filesize": 18615907, "license": "other", "mime_type": "application/pdf", "url": "/2981/16/Powell_re_1981.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Geology of the Crystalline Basement Complex, Eastern Transverse Ranges, Southern California: Constraints on Regional Tectonic Interpretation", "author": [ { "family_name": "Powell", "given_name": "Robert Edward", "clpid": "Powell-Robert-Edward" } ], "thesis_advisor": [ { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" }, { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" } ], "thesis_committee": [ { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Kamb", "given_name": "W. Barclay", "clpid": "Kamb-W-B" }, { "family_name": "Saleeby", "given_name": "Jason B.", "clpid": "Saleeby-J-B" }, { "family_name": "Sieh", "given_name": "Kerry E.", "orcid": "0000-0002-7311-2447", "clpid": "Sieh-K-E" }, { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" }, { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "About 3000 km2 within the crystalline basement complex of the Eastern Transverse Ranges in the Chuckwalla, Orocopia, Eagle, Cottonwood, Hexie, Little San Bernardino, and Pinto Mountains of Riverside County, California were mapped at scales of 1:36,000 and 1:62,500 and compiled at 1:125,000 (Plate I). Pre-Jurassic(?) (i.e., older than the Mesozoic batholiths) rocks of the crystalline complex comprise two lithologically distinct terranes. These terranes are called the Joshua Tree and San Gabriel terranes for regions of southern California in which their lithologies were initially characterized. The two terranes are superposed along a previously unrecognized low-angle fault system of regional extent, the Red Cloud thrust.
\r\n\r\nDuring the course of this study, the structurally lower Joshua Tree terrane has been defined as a stratigraphically coherent group of crystalline rocks that consists of Precambrian granite capped by a paleo-weathered zone and overlain nonconformably by orthoquartzite that interfingers westward with pelitic and feldspathic granofelses. The quartzite contains near-basal quartz/quartzite clast conglomerates, and has well-preserved cross-bedding that appears upright wherever it has been observed. Pelitic and feldspathic granofelses crop out to the west of the quartzite exposures in four lithologically different belts that trend northnorthwest throughout the area mapped. These lithologic belts are interpreted to have been derived from stratigraphically interfingering sedimentary protoliths deposited in a basin offshore from a quartzose beach-sand protolith. In proximity to the early Red Cloud thrust, this whole stratigraphic package was pervasively deformed to granite gneiss, stretched pebble conglomerate, lineated quartzite, and schist.
\r\n\r\nA northeast-trending pattern of metamorphic isograds was orthogonally superimposed on the northnorthwest-trending protoliths of the Pinto gneiss. A central andalusite zone, located in the southern Little San Bernardino and Hexie, and northern Eagle Mountains, is flanked to the northwest and southeast by sillimanite zones. Coincident with this symmetrical distribution of aluminosilicates is an asymmetrical distribution of other pelitic mineral zones, with prograde cordierite-aluminosilicate-biotite- and K-feldspar-aluminosilicate-bearing assemblages to the northwest in the northern Little San Bernardino and Pinto Mountains, staurolite-bearing assemblages in a narrow zone in the southern Little San Bernardino-Hexie and northern Eagle Mountains, and retrograde chlorite-muscovite-bearing assemblages in the southernmost Little San Bernardino, Cottonwood, southern Eagle, Orocopia, and Chuckwalla Mountains. One occurrence of chloritoid-sillimanite in the central Eagle Mountains is apparently also retrograde. The crossing isograds are interpreted to result from a temporal increase in PH2O relative to PT from south to north through the field area. Comparison of the pelitic assemblages with experimental studies suggests peak conditions of PT \u2248 3.5 to 4 kb, T \u2248 525 to 625\u00b0C. The early prograde metamorphism pre-dated the thrusting event; the retrograde stage may have overlapped in time with the emplacement of the San Gabriel terrane allochthon. Cordierite-orthoamphibole-bearing assemblages are present in one stratigraphic zone of the Pinto gneiss.
\r\n\r\nIn this study, the Precambrian lithologies of the San Gabriel terrane are viewed as a three-part deep crustal section, with uppermost amphibolite grade pelitic (Hexie) gneiss intruded by granodioritic (Soledad) augen gneiss at the highest level, retrograded granulite (Augustine) gneiss at an intermediate level, and syenite-mangerite-jotunite at the lowest level exposed in the Eastern Transverse Ranges. The Hexie gneiss, characterized by sillimanite-garnet-biotite-bearing assemblages, is thrust over andalusite-bearing granofels of the Pinto gneiss.
\r\n\r\nThe Red Cloud thrust system is inferred to have developed in three or four sequential structural events: 1) early thrusting that probably moved parallel to the ENE mineral lineations recorded in both plates; 2) regional folding of the initial thrust surface around NNE-trending axes; 3) later thrusting that broke with some component of westward movement across a fold in the older thrust surface to produce a stacking of crystalline thrust plates of the two terranes; 4) continued or renewed folding of both thrust faults with eventual overturning toward the SW. It is consistent with all observations to date to link these structural events into a single regional tectonic episode that resulted in westward-vergent allochthonous emplacement of the San Gabriel terrane over Joshua Tree terrane. The thrust timing can only be loosely bracketed in time between 1195 m.y. and 165 m.y. ago.
\r\n\r\nThe pre-batholithic terranes and the westward-vergent Red Cloud thrust are considered to be exotic with respect to the pre-batholithic rocks and structures exposed to the north and east of the field area. The bounding discontinuity has been obliterated by intrusion of both suites of Mesozoic batholithic rocks.
\r\n\r\nThe Mesozoic plutonic rocks comprise two batholithic suites, both of which intrude the Joshua Tree and San Gabriel terranes and the Red Cloud thrust system. NW-SE trending belts of plutonic lithologies have been mapped within each suite: the oldest lithology of the younger suite intrudes the youngest lithology of the older suite. The older suite, Jurassic(?), lying to the NE, appears to have an alkalic character; the younger suite, Cretaceous(?), appears calc-alkaline. The older suite consists of biotite- and K-feldspar-bearing gabbro-diorites intruded by low-quartz monzogranites. The younger suite includes hornblende-biotite-sphene granodiorite intruded by porphyritic monzogranites, intruded in turn by nonporphyritic monzogranite.
\r\n\r\nThe Eastern Transverse Ranges south of the Pinto Mountain fault are defined by several Cenozoic E-W left-lateral strike-slip faults that have a cumulative westward displacement from S to N of about 50 km. The left-lateral faults are interpreted to form part of a conjugate fault set with complementary right-lateral faults in the Mojave and Colorado Deserts. Along the western boundary of the Eastern Transverse Ranges in the Little San Bernardino Mountains, the crystalline rocks have been pervasively cataclasized by an event that post-dates intrusion of the Cretaceous(?) plutonic rocks. The cataclasis is attributed to the Vincent-Orocopia-Chocolate Mountain thrust that is thought to superpose the diverse pre-batholithic and batholithic rocks of the Eastern Transverse Ranges above Pelona-type schist. The cataclastic foliation is folded along the length of the Little San Bernardino Mountains in an antiform that is inferred to be cored with Pelona-type schist. This fold may have formed a single antiformal feature comprising all the crystalline-rock antiforms now recognized along the San Andreas fault that are cored by Pelona-type schist. Displacements of the piercing points formed by the antiformal axis apparently indicate 220 km of right-lateral offset on the present San Andreas strand and about 80 km of right-lateral offset along a fragmented older San Andreas strand that consisted of the San Francisquito, Fenner, and Clemens Well faults and a buried extension of this fault beneath the alluvial fill of the valley between the Chocolate and Chuckwalla Mountains.
\r\n", "doi": "10.7907/F22F-YX04", "publication_date": "1981", "thesis_type": "phd", "thesis_year": "1981" }, { "id": "thesis:2718", "collection": "thesis", "collection_id": "2718", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06242009-141311", "primary_object_url": { "basename": "Smith_rsu_1976.pdf", "content": "final", "filesize": 32480924, "license": "other", "mime_type": "application/pdf", "url": "/2718/1/Smith_rsu_1976.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Late-Quaternary Pluvial and Tectonic History of Panamint Valley, Inyo and San Bernardino Counties, California", "author": [ { "family_name": "Smith", "given_name": "Roger Stanley Uhr", "clpid": "Smith-Roger-Stanley-Uhr" } ], "thesis_advisor": [ { "family_name": "Sharp", "given_name": "Robert P.", "clpid": "Sharp-R-P" } ], "thesis_committee": [ { "family_name": "Sharp", "given_name": "Robert P.", "clpid": "Sharp-R-P" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" }, { "family_name": "Smith", "given_name": "George I.", "clpid": "Smith-G-I" }, { "family_name": "Rossman", "given_name": "George Robert", "orcid": "0000-0002-4571-6884", "clpid": "Rossman-G-R" }, { "family_name": "Birman", "given_name": "Joseph Harold", "clpid": "Birman-J-H" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "Panamint Valley was filled to overflowing on five, possibly six, separate instances, fed largely by runoff from the Sierra Nevada discharged through Owens and Searles lakes. These high water levels are best represented by uplifted lake terraces and associated deposits at Pleasant Canyon on the, west face of the Panamint Range, where shorelines at five, possibly six, levels have formed with respect to the level of Wingate Pass, (present elevation 1977 \u00b11 feet) into Death Valley. The level of this sill seems to have been tectonically stable, but was permanently raised about 50 feet by a mudflow which poured into the pass during a long-lasting lake stage, herein named Gale Stage. Paired Gale-Stage shorelines, attributed to lake stands stabilized at pre- and post-mudflow sill levels are found throughout Panamint Valley. The lower shoreline is 1.26 times older than the higher, more prominent shoreline, based on 1.26 times greater tectonic deformation at most localities. On the rising range block at Pleasant Canyon, the higher shoreline seems superposed on the lower to form a composite shoreline at 2177\u00b110 feet elevation. Shoreline elevations at Pleasant Canyon (and probable uplift they experienced) are: 2410\u00b110 feet (480\u00b125 feet); 2298\u00b110 (368\u00b125); 2265\u00b110 (335\u00b125); 2177\u00b110 (247\u00b125 to 200\u00b111); 2127\u00b110 (150\u00b111); and 2040\u00b140? (63\u00b141?). If the long-term uplift rate has been constant, the age of each shoreline should be proportional to its height above its sill level. Relatively steady deformation rates throughout Panamint Valley are suggested by the constant proportion (1.26:1.00) of deformation between the older (lower) and younger (higher) Gale-Stage shorelines.\r\n\r\nA radiocarbon age of 31,150\u00b11400 B.P. on snail shells establishes a minimum age for the shoreline at 2127 feet. Extrapolation using steady uplift rates indicates the following youngest-possible ages (in thousands of years) for the other uplifted shorelines: 2410 ft: 100\u00b117; 2298 ft: 77\u00b114; 2265 ft: 70\u00b113; 2177 ft: 52 to 42\u00b17; and 2040 ft?,: 14\u00b110?. The probable age of each lake stage is about 20 per cent greater than its youngest possible age, a judgement based on correlation with the stages of Searles Lake (G.I. Smith, 1968).\r\n\r\nThe higher, younger Gale-Stage shoreline is prominent throughout Panamint Valley. Differential tectonic deformation of this feature amounts to about 370 feet, as established by a maximum elevation of 2190\u00b110 feet on the central Panamint Range to a minimum of 1820\u00b120 at Panamint Valley's north end. Deformation involves differential north- south warping of crustal block on both sides of the Panamint Valley and Ash Hill fault zones, which respectively define the east and west margins of Panamint Valley.\r\n\r\nRight-lateral displacement of Quaternary features along the Panamint Valley fault zone exceeds their vertical, offset. Sixty feet of right-lateral offset have occurred since desiccation of the last, low lake to occupy Panamint Valley (15,000\u00b15,000 B.P.), and cumulative offset of a sheet of monolithologic (landslide?) breccia of Plio-Pleistocene age from its probable source in Wildrose Canyon may total 10,000 to 15,000 feet.\r\n\r\nPanamint Valley is abruptly and massively closed at its north end, where valley-floor deposits appear to underthrust Mesozoic plutonic rocks of Hunter Mountain along a northwest-trending zone which may represent the northwestward continuation of the Panamint Valley fault zone. Along the middle part of this reach of the zone, poorly-sorted (talus?) rubble of sound crystalline boulders underlies a 50 to 100-foot-thick zone of crushed crystalline rock which dips 17 to 35 degrees to the northeast beneath unshattered crystalline rocks. Thrusting may reflect a response to regional northwest-southeast right-lateral shear, possibly imposed upon classical Basin-Range bounding faults. The complex pattern of warping and faulting throughout the rest of Panamint Valley is also consistent with right-lateral shear, and the valley itself may have originated as a right-lateral \"pull apart\".\r\n\r\nThe unusually large volume of deposits along the 2177-foot shoreline suggests correlation with the Sierra Nevada Tahoe glaciation, which is distinguished by unusually large moraines. The small volume of 2127-foot shoreline deposits suggests correlation with the Tenaya glaciation, whose moraines are small. Thus the queried 2040-foot shoreline could represent the Tioga glaciation and the 2410-foot shoreline the Mono Basin glaciation. The 2265 and 2298-foot shorelines may represent early Tahoe events, suggesting that the Tahoe may be divided into early and late phases. Tentative ages of glaciations, based on correlation with pluvial events in Panamint Valley, are (in thousands of years B.P.): Mono Basin: 120\u00b120; Tahoe (early): 92\u00b115 to 78\u00b115; Tahoe (late): 65\u00b113 to 48\u00b110; Tenaya: 38\u00b16; Tioga?: 23\u00b110?.", "doi": "10.7907/W934-HC84", "publication_date": "1976", "thesis_type": "phd", "thesis_year": "1976" }, { "id": "thesis:8100", "collection": "thesis", "collection_id": "8100", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02272014-085454874", "primary_object_url": { "basename": "Joesten-rl-1974.pdf", "content": "final", "filesize": 76432892, "license": "other", "mime_type": "application/pdf", "url": "/8100/1/Joesten-rl-1974.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Metasomatism and Magmatic Assimilation at a Gabbro-Limestone Contact, Christmas Mountains, Big Bend Region, Texas", "author": [ { "family_name": "Joesten", "given_name": "Raymond Leonard", "clpid": "Joesten-Raymond-Leonard" } ], "thesis_advisor": [ { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" } ], "thesis_committee": [ { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" }, { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" }, { "family_name": "Rossman", "given_name": "George Robert", "orcid": "0000-0002-4571-6884", "clpid": "Rossman-G-R" }, { "family_name": "Ahrens", "given_name": "Thomas J.", "clpid": "Ahrens-T-J" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "A composite stock of alkaline gabbro and syenite is intrusive into limestone of the Del Carmen, Sue Peake and Santa Elena Formations at the northwest end of the Christmas Mountains. There is abundant evidence of solution of wallrock by magma but nowhere are gabbro and limestone in direct contact. The sequence of lithologies developed across the intrusive contact and across xenoliths is gabbro, pyroxenite, calc-silicate skarn, marble. Pyroxenite is made up of euhedral crystals of titanaugite and sphene in a leucocratic matrix of nepheline, Wollastonite and alkali feldspar. The uneven modal distribution of phases in pyroxenite and the occurrence' of nepheline syenite dikes, intrusive into pyroxenite and skarn, suggest that pyroxenite represents an accumulation of clinopyroxene \"cemented\" together by late-solidifying residual magma of nepheline syenite composition. Assimilation of limestone by gabbroic magma involves reactions between calcite and magma and/or crystals in equilibrium with magma and crystallization of phases in which the magma is saturated, to supply energy for the solution reaction. Gabbroic magma was saturated with plagioclase and clinopyroxene at the time of emplacement. The textural and mineralogic features of pyroxenite can be produced by the reaction 2( 1-X) CALCITE + ANXABl-X = (1-X) NEPHELINE+ 2(1-X) WOLLASTONITE+ X ANORTHITE+ 2(1-X) CO2. Plagioclase in pyroxenite has corroded margins and is rimmed by nepheline, suggestive of resorption by magma. Anorthite and wollastonite enter solid solution in titanaugite. For each mole of calcite dissolved, approximately one mole of clinopyroxene was crystallized. Thus the amount of limestone that may be assimilated is limited by the concentration of potential clinopyroxene in the magma. Wollastonite appears as a phase when magma has been depleted in iron and magnesium by crystallization of titanaugite. The predominance of mafic and ultramafic compositions among contaminated rocks and their restriction to a narrow zone along the intrusive contact provides little evidence for the generation of a significant volume of desilicated magma as a result of limestone assimilation.
\r\n\r\nWithin 60 m of the intrusive contact with the gabbro, nodular chert in the Santa Elena Limestone reacted with the enveloping marble to form spherical nodules of high-temperature calc-silicate minerals. The phases wollastonite, rankinite, spurrite, tilleyite and calcite, form a series of sharply-bounded, concentric monomineralic and two-phase shells which record a step-wise decrease in silica content from the core of a nodule to its rim. Mineral zones in the nodules vary 'with distance from the gabbro as follows:
\r\n0-5 m CALCITE + SPURRITE + RANKINITE + WOLLASTONITE
\r\n5-16 m CALCITE + TILLEYITE \u00b1 SPURRITE + RANKINITE + WOLLASTONITE
\r\n16-31 m CALCITE + TILLEYITE + WOLLASTONITE
\r\n31-60 m CALCITE + WOLLASTONITE
\r\n60-plus CALCITE + QUARTZ
\r\n\r\nThe mineral of a one-phase zone is compatible with the phases bounding it on either side but these phases are incompatible in the same volume of P-T-XCO2.
Growth of a monomineralio zone is initiated by reaction between minerals of adjacent one-phase zones which become unstable with rising temperature to form a thin layer of a new single phase that separates the reactants and is compatible with both of them. Because the mineral of the new zone is in equilibrium with the phases at both of its contacts, gradients in the chemical potentials of the exchangeable components are established across it. Although zone boundaries mark discontinuities in the gradients of bulk composition, two-phase equilibria at the contacts demonstrate that the chemical potentials are continuous. Hence, Ca, Si and CO2 were redistributed in the growing nodule by diffusion. A monomineralic zone grows at the expense of an adjacent zone by reaction between diffusing components and the mineral of the adjacent zone. Equilibria between two phases at zone boundaries buffers the chemical potentials of the diffusing species. Thus, within a monomineralic zone, the chemical potentials of the diffusing components are controlled external to the local assemblage by the two-phase equilibria at the zone boundaries.
\r\n\r\nMineralogically zoned calc-silicate skarn occurs as a narrow band that separates pyroxenite and marble along the intrusive contact and forms a rim on marble xenoliths in gabbro. Skarn consists of melilite or idocrase pseudomorphs of melili te, one or two . stoichiometric calcsilicate phases and accessory Ti-Zr garnet, perovskite and magnetite. The sequence of mineral zones from pyroxenite to marble, defined by a characteristic calc-silicate, is wollastonite, rankinite, spurrite, calcite. Mineral assemblages of adjacent skarn zones are compatible and the set of zones in a skarn band defines a facies type, indicating that the different mineral assemblages represent different bulk compositions recrystallized under identical conditions. The number of phases in each zone is less than the number that might be expected to result from metamorphism of a general bulk composition under conditions of equilibrium, trivariant in P, T and uCO2. The \"special\" bulk composition of each zone is controlled by reaction between phases of the zones bounding it on either side. The continuity of the gradients of composition of melilite and garnet solid solutions across the skarn is consistent with the local equilibrium hypothesis and verifies that diffusion was the mechanism of mass transport. The formula proportions of Ti and Zr in garnet from skarn vary antithetically with that of Si Which systematically decreases from pyroxenite to marble. The chemical potential of Si in each skarn zone was controlled by the coexisting stoichiometric calc-silicate phases in the assemblage. Thus the formula proportion of Si in garnet is a direct measure of the chemical potential of Si from point to point in skarn. Reaction between gabbroic magma saturated with plagioclase and clinopyroxene produced nepheline pyroxenite and melilite-wollastonite skarn. The calcsilicate zones result from reaction between calcite and wollastonite to form spurrite and rankinite.
\r\n\r\n", "publication_date": "1974", "thesis_type": "phd", "thesis_year": "1974" }, { "id": "thesis:8092", "collection": "thesis", "collection_id": "8092", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02202014-142721576", "type": "thesis", "title": "Oxygen, Carbon, and Hydrogen Isotope Studies of Contact Metamorphism", "author": [ { "family_name": "Shieh", "given_name": "Yuch-Ning", "clpid": "Shieh-Yuch-Ning" } ], "thesis_advisor": [ { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" } ], "thesis_committee": [ { "family_name": "Taylor", "given_name": "Hugh P.", "clpid": "Taylor-H-P" }, { "family_name": "Epstein", "given_name": "Samuel", "clpid": "Epstein-S" }, { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" }, { "family_name": "Albee", "given_name": "Arden Leroy", "clpid": "Albee-A-L" }, { "family_name": "Burnett", "given_name": "Donald S.", "orcid": "0000-0001-9521-8675", "clpid": "Burnett-D-S" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "The O18/O16, C13/C12, and D/H ratios have been determined for\r\nrocks and coexisting minerals from several granitic plutons and their contact\r\nmetamorphic aureoles in northern Nevada, eastern California, central Colorado,\r\nand Texas, with emphasis on oxygen isotopes. A consistent order of O18/O16, C13/C12, and D/H enrichment in coexisting minerals, and a correlation between isotopic fractionations among coexisting mineral pairs are in general\r\nobserved, suggesting that mineral assemblages tend to approach isotopic\r\nequilibrium during contact metamorphism. In certain cases, a correlation is\r\nobserved between oxygen isotopic fractionations of a mineral pair and sample\r\ndistance from intrusive contacts. Isotopic temperatures generally show good\r\nagreement with heat flow considerations. Based on the experimentally\r\ndetermined quartz-muscovite O18/O16 fractionation calibration curve, temperatures are\r\nestimated to be 525 to 625\u00b0C at the contacts of the granitic stocks\r\nstudied.
\r\n\r\nSmall-scale oxygen isotope exchange effects between intrusive and\r\ncountry rock are observed over distances of 0.5 to 3 feet on both sides of the\r\ncontacts; the isotopic gradients are typically 2 to 3 per mil per foot. The\r\ndegree of oxygen isotopic exchange is essentially identical for different\r\ncoexisting minerals. This presumably occurred through a diffusion-controlled\r\nrecrystallization process. The size of the oxygen isotope equilibrium systems\r\nin the small-scale exchanged zones vary from about 1.5 cm to 30 cm. A\r\nxenolith and a re-entrant of country rock projecting into on intrusive hove\r\nboth undergone much more extensive isotopic exchange (to hundreds of feet);\r\nthey also show abnormally high isotopic temperatures. The marginal portions\r\nof most plutons have unusually high O18/O16 ratios compared to \"normal\"\r\nigneous rocks, presumably due to large-scale isotopic exchange with meta-sedimentary\r\ncountry rocks when the igneous rocks were essentially in a molten\r\nstate. The isotopic data suggest that outward horizontal movement of H2O\r\ninto the contact metamorphic aureoles is almost negligible, but upward movement\r\nof H2O may be important. Also, direct influx and absorption of water from the\r\ncountry rock may be significant in certain intrusive stocks.
\r\n\r\nExcept in the exchanged zones, the O18/O16 ratios of pelitic rocks\r\ndo not change appreciably during contact metamorphism, even in the cordierite\r\nand sillimanite grades; this is in contrast to regional metamorphic rocks which\r\ncommonly decrease in O18 with increasing grade. Low O18/O16 and C13/C12\r\nratios of the contact metamorphic marbles generally correlate well with the\r\npresence of calc-silicate minerals, indicating that the CO2 liberated during\r\nmetamorphic decarbonation reactions is enriched in both O18 and C13 relative to the carbonates.
\r\n\r\nThe D/H ratios of biotites in the contact metamorphic rocks and their\r\nassociated intrusions show a geographic correlation that is similar to that shown\r\nby the D/H ratios of meteoric surface waters, perhaps indicating that meteoric\r\nwaters were present in the rocks during crystallization of the biotites.
\r\n\r\n", "doi": "10.7907/JJY7-J871", "publication_date": "1969", "thesis_type": "phd", "thesis_year": "1969" } ]