@book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/83973, title ="Source Functions and Path Effects from Earthquakes in the Farallon Transform Fault Region, Gulf of California, Mexico that Occurred on October 2013", author = "Castro, Raúl R. and Stock, Joann M.", volume = "1", pages = "45-62", month = "December", year = "2017", issn = "2504-3625", isbn = "978-3-319-71564-3", url = "https://resolver.caltech.edu/CaltechAUTHORS:20171220-093808988", note = "© 2018 Springer International Publishing AG. \n\nFirst Online: 21 December 2017. \n\nReprinted from: Pure Appl. Geophys. 174 (2017), 2239–2256, 2016 Springer International Publishing. DOI 10.1007/s00024-016-1346-4. \n\nThe operation of the RESBAN network has been possible thanks to the financial support of the Mexican National Council for Science and Technology (CONACYT) (projects CB-2011-01-165401(C0C059), G33102-T and 59216). This paper was prepared while the first author (RRC) was on sabbatical year in Caltech. We thank Prof. Gurnis for the support provided. Dr. Lenin Avila-Barrientos facilitated part of the spectral records used to calculate the site functions. Antonio Mendoza Camberos pre-process the data from the RESBAN network and Arturo Perez Vertti maintains and operates the stations. We thank Dr. Edwards and the anonymous reviewer for their careful revisions, comments and suggestions which help us to improve the manuscript. We also acknowledge the Editor, Dr. Thomas H.W. Goebel.", revision_no = "15", abstract = "We determined source spectral functions, Q and site effects using regional records of body waves from the October 19, 2013 (M_w = 6.6) earthquake and eight aftershocks located 90 km east of Loreto, Baja California Sur, Mexico. We also analyzed records from a foreshock with magnitude 3.3 that occurred 47 days before the mainshock. The epicenters of this sequence are located in the south-central region of the Gulf of California (GoC) near and on the Farallon transform fault. This is one of the most active regions of the GoC, where most of the large earthquakes have strike–slip mechanisms. Based on the distribution of the aftershocks, the rupture propagated northwest with a rupture length of approximately 27 km. We calculated 3-component P- and S-wave spectra from ten events recorded by eleven stations of the Broadband Seismological Network of the GoC (RESBAN). These stations are located around the GoC and provide good azimuthal coverage (the average station gap is 39◦). The spectral records were corrected for site effects, which were estimated calculating average spectral ratios between horizontal and vertical components (HVSR method). The site-corrected spectra were then inverted to determine the source functions and to estimate the attenuation quality factor Q. The values of Q resulting from the spectral inversion can be approximated by the relations Q_P = 48.1 1±1^(f0:880:04) and QS = 135:4 1:1f ±^(0:580:03) and are consistent with previous estimates reported by Vidales-Basurto et al. (Bull Seism Soc Am 104:2027–2042, 2014) for the south-central GoC. The stress drop estimates, obtained using the ω^2 model, are below 1.7 MPa, with the highest stress drops determined for the mainshock and the aftershocks located in the ridge zone. We used the values of Q obtained to recalculate source and site effects with a different spectral inversion scheme. We found that sites with low S-wave amplification also tend to have low P-wave amplification, except for stations BAHB, GUYB and SFQB, located on igneous rocks, where the P-wave site amplification is higher.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/45228, title ="Seismic Calibration Shots Conducted in 2009 in the Imperial Valley, Southern California, for the Salton Seismic Imaging Project (SSIP)", author = "Murphy, Janice and Goldman, Mark", number = "2010-1295", pages = "1-76", month = "January", year = "2011", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140425-103722434", note = "We thank Caltrans (State of California) for allowing us to operate on their land and put seismic recorders in their road right-of-way. We are grateful to the staff at the IRIS-PASSCAL Instrument Center for their help with the instrumentation and software. We especially thank Caltech students Steven Skinner, Yunung Nina Lin, and Wang Yu for their help in the field. They worked tirelessly in temperatures well over 100 degrees and late into the night to the early hours of the morning.", revision_no = "13", abstract = "The Salton Seismic Imaging Project (SSIP) is a large-scale collaborative project with the goal of developing a detailed 3-D structural image of the Salton Trough (including both the Coachella and Imperial Valleys). The image will be used for earthquake hazard analysis, geothermal studies, and studies of plate-boundary transition from an ocean-ocean to a continent-continent plate-boundary.\nAs part of SSIP, a series of calibration shots were detonated in June 2009 in the southern Imperial Valley for four specific reasons: (1) to measure peak particle velocity and acceleration at various distances from the shots, (2) to calibrate the propagation of energy through sediments of the Imperial Valley, (3) to test the effects of seismic energy on buried clay drainage pipes, which are abundant throughout the irrigated parts of the Salton Trough, and (4) to test the ODEX drilling technique, which uses a downhole casing hammer for a tight casing fit.\nCurrently, we are using information obtained from the calibration shots to plan the data collection phase of the SSIP project. We have validated the use of ground-motion tables developed with Los Angeles Region Seismic Experiment (LARSE) data for use in the Imperial Valley and we have demonstrated that seismic energy from shots will not damage the drainage pipes used throughout the Salton Trough for irrigation.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/50495, title ="Constraints on the timing of extension in the Northern Basin, Ross Sea", author = "Cande, Steven C. and Stock, Joann M.", pages = "319-326", month = "January", year = "2006", isbn = "978-3-540-30673-3", url = "https://resolver.caltech.edu/CaltechAUTHORS:20141017-125224927", note = "© 2006 Springer-Verlag Berlin Heidelberg\n\nWe thank the captains, officers, crew and scientific staff\nof the R/VIB \"Nathaniel Palmer\" for their dedicated Efforts\nDr. Takemi Ishihara generously provided us with\nseismic reflection and magnetics data from the RV\n\"Hakurei Maru\". Two anonymous reviewers provided\nhelpful comments This work was supported by NSF grants\nOPP-03-38346 (Cande) and OPP-03-38317 (Stock).", revision_no = "13", abstract = "Recent kinematic constraints for the region north of the western Ross Sea suggest that there was approximately 150 km of seafloor spreading in the Adare Basin, northeast of Cape Adare, between Chrons 20 and 8 (43 to 26 Ma). This kinematic history has important implications since the 150 km of extension in the Adare Basin occurred immediately north along strike from the Northern Basin of the Ross Sea, whose extensional history is not well known. This paper examines the transition from the structures in the Adare Basin to the structures of the Northern Basin and speculates on the manner in which the extension was accommodated in the Ross Sea. Magnetic anomaly data in the Adare Basin document a sequence of anomalies 18 to 12 formed during a period of very slow spreading. The easternmost part of this sequence, anomalies 16 to 18, coalesces into a single positive anomaly near 72° S, forming a distinct anomaly that can be traced southward from the Adare Basin across the continental margin and down the east side of the Northern Basin to a latitude of roughly 73° S. This observation has important implications for the tectonic history of the Ross Sea since it suggests that most of the extension in the Adare Basin continued into the Northern Basin. This, in turn, suggests that the Northern Basin was formed by a combination of crustal thinning and massive, narrowly focused intrusions.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/45231, title ="Cenozoic Reconstructions of the Australia-New Zealand-South Pacific Sector of Antarctica", author = "Cande, Steven C. and Stock, Joann M.", number = "151", pages = "5-17", month = "January", year = "2004", doi = "10.1029/151GM02", isbn = "9780875904160", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140425-125510082", note = "© 2004 American Geophysical Union.\nWe thank Rob Larter and Carmen Gaina for\ntheir helpful reviews and Neville Exon for hi editorial suggestions.\nGMT software was used to produce the figures [Wessel and Smith, 1991]. This research was supported by NSF grant OPP-0126340\n(UCSD) and OPP-0126334 (Caltech). California Institute of\nTechnology Division of Geological and Planetary Science contribution\nnumber 8956.", revision_no = "14", abstract = "Reconstructions are presented documenting the relative motion of the Australia.\nAntarctic and Pacific plates since Chron 27 (61.1 Ma). In addition to the motion of\nthe major plates, the reconstructions show the relative motion between East and\nWest Antarctica and the continental fragments that make up the South Tasman\nRise. Recent observations that are used in making these reconstructions include the\nmapping of seafloor spreading magnetic anomalies in the Adare basin, northeast of\nCape Adare, which recorded roughly 150 km of opening between East and West\nAntarctica between Chrons 20 (43.8 Ma) and 8 (26.6 Ma). In addition, magnetic\nand bathymetric observations from the lselin Rift, northeast of the Iselin Bank, and\nfrom the Emerald Fracture Zone, along the western boundary of Pacific-Antarctic\nspreading, document the rotation of the Iselin Bank between Chrons 27 and 24\n(53.3 Ma). Our reconstructions indicate that there was a total of about 200 km of\nseparation between East and West Antarctica in the northern Ross Sea region in the\nCenozoic. These reconstructions document the development of a deep-water\npassageway between Australia and Antarctica as the South Tasman Rise clears the\nfinal piece of the Antarctic continental margin around Chron 13 (33.5 Ma).", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/45119, title ="Cenozoic volcanism and tectonics of the continental margins of the Upper Delfín basin, northeastern Baja California and western Sonora", author = "Oskin, Michael and Stock, Joann", number = "374", pages = "421-438", month = "January", year = "2003", doi = "10.1130/0-8137-2374-4.421", isbn = "9780813723747", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140422-142537032", note = "© 2003 Geological Society of America.\nManuscript accepted by the Society June 2, 2003.\n\nThis work was supported by National Science Foundation\ngrants EAR-9614674 and EAR-0001248. We also appreciate\nthe support of C. González-León of the Universidad Nacional\nAutónoma de México. Permission to enter Isla Tiburón was\ngranted by the Secretaría de Medio Ambiente y Recursos Naturales\nand the Cumcaác (Seri) Indian Tribe. E. Molina, C. Lewis,\nS. Dobner, R. Houston, N. Marks, J. Wise, and L. Perg assisted\nwith field studies. Discussions with C. Lewis, E. Nagy, A. Martín-\nBarajas, and R. Dorsey contributed to development of this\npaper, and reviews by D. Kimbrough and R. Dorsey substantially\nimproved the manuscript and figures. California Institute\nof Technology, Division of Geological and Planetary Sciences\ncontribution #8868.", revision_no = "17", abstract = "Pre- and syn-rift stratigraphy of conjugate rifted margins of the Upper Delfín\nbasin provides a rare opportunity to explore proximal relationships between the loci\nof volcanism and rifting during formation of new ocean basin. The Upper Delfín basin\nis one of a series of youthful, en-echelon ocean basins that accommodate spreading\nbetween the Pacific and North American plates in the Gulf of California. Four groups\nof volcaniclastic stratigraphy are described from the Baja California rifted margin\nfrom the Pucrtecitos Volcanic Province to the Sierra San Felipe and from the conjugate\nSonora rifted margin from Isla Tiburón to the adjacent mainland coastal\nregion. Excluding the uppermost post-6 Ma group, these strata predate opening of\nthe Upper Delfín basin and thus similar facies relationships occur on both conjugate\nrift margins. Pre-rift, mostly arc-related volcanism from 21 to 12 Ma built isolated\nvolcanic centers over a regional Eocene(?) erosion surface cut onto pre-Tertiary\nbasement rocks. The Puertecitos Volcanic Province formed as a concentration of arcrelated\nvolcanism with a peak of activity at 18-15 Ma. Rift-related faulting and basin\nformation initiated after 12.6 Ma to the north and cast of the Puertecitos Volcanic\nProvince, but extension largely bypassed the center of the volcanic province. Rather,\nrifting stepped eastward along the Matomi Accommodation Zone, perhaps by taking\nadvantage of crust weakened by prior arc-related volcanism in the Puertecitos Volcanic\nProvince. Later rift-related volca nism localized along intersections of the Mato mi\nAccommodation Zone and north-striking extensional faults. The crustal break that\nopened the Upper Delfín basin ca. 6 Ma coincides with the most voluminous exposures\nof late Miocene syn-rift volcanism and the vent area for 6.7-6.1 Ma rhyolite\nignimbrites that blanketed the region just prior to the onset of marine sedimentation.\nOverall, the pattern of arc- and rift-related volcanism, sedimentation, and faulting on\nthe margins of the Upper Delfín basin indicates a close association between continental\nextension and volcanism. These relationships support that magmatism and crustal\nrift structure evolved as a coupled system to localize Pacific-North America plate\nmotion into the Gulf of California.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/45141, title ="Tectonic history of Antarctic seafloor in the Australia-New Zealand-South Pacific sector: implications for Antarctic continental tectonics", author = "Stock, J. M. and Cande, S. C.", number = "35", pages = "251-259", month = "January", year = "2002", isbn = "1877264067", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140423-104037295", note = "© The Royal Society of New Zealand. Last updated\n2012-06-07. We thank Carol Raymond, Bruce Luyendyk, Geoff Rait, and Dick Walcott for helpful reviews of the manuscript. California Institute of Technology, Division of Geological and Planetary Science, contribution number 8692. This research was supported by US National Science Foundation grants OPP-9814579 and OPP-98-1528.", revision_no = "14", abstract = "We review the seafloor spreading record of plate motions adjacent to the Antarctic continent during and after Cretaceous separation of the New Zealand and Australia continental fragments from Antarctica. The earliest seafloor in this region (c. 95-83 Ma) records separation of Australia from Antarctica and separation of the Lord Howe rise from eastern Australia. At this time, continental extension occurred between the Campbell Plateau/Chatham Rise and Marie Byrd Land with oblique subduction of Phoenix plate fragments (Aluk and Bellingshausen) beneath the West Antarctic margin from c. 125ºW to at least 90ºW. Seafloor spreading started first (Chron 34, before 83 Ma) in the mouth of the rift, between the Chatham Rise and the Bellingshausen plate, and later (Chron 33, c. 79 Ma) between the Campbell Plateau and Marie Byrd Land, joining the Tasman sea ridge to the southwest Pacific spreading centre. Subsequent tectonic events include: (1) <50 km of rifting of the seafloor adjacent to Marie Byrd Land along the northeast-trending Iselin trough, east of the Iselin Bank, from Chrons 27 to 24 (61-55 Ma); (2) propagation of the southeast Indian Ridge between the south Tasman Rise and Victoria Land to join the Tasman Sea spreading centre by Chron 27 (61 Ma); (3) capture of the Bellingshausen plate by West Antarctica by about Chron 27; (4) 150-180 km of separation between East Antarctica and West Antarctica (Iselin Bank) centred on the NNW-trending Adare trough between Chrons 18 and 9 (40-27 Ma). These observations predict, first, that the West Antarctic margin at 125ºW was the site of a triple junction from at least 84 to 61 Ma, with Phoenix plate annihilation and expected tectonics of West Antarctica in many ways analogous to breakup of the Farallon plate and its effects on western North America. Second, northern Victoria Land may exhibit unique tectonics compared to elsewhere along this part of the Antarctic margin because it lay in a continental strike-slip regime, sliding against continental crust of the Australia plate (western south Tasman Rise) until Eocene time. Finally, the 150+ km of Oligocene seafloor formed at the Adare Trough implies a significant extensional event of this age farther south in the Ross Sea, in agreement with results from recent drilling at Cape Roberts hole CRP-3.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/44992, title ="Fast Paleogene Motion of the Pacific Hotspots From Revised Global Plate Circuit Constraints", author = "Raymond, Carol A. and Stock, Joann M.", number = "121", pages = "359-375", month = "January", year = "2000", doi = "10.1029/GM121p0359", isbn = "9780875909790", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140416-153704888", note = "© 2000 American Geophysical Union.\nThis work benefited from discussions\nwith many people, especially Richard Gordon, Bernhard Steinberger,\nTodd Ratcliff, Dietmar Mueller, Chuck DeMets and\nGary Acton. Reviews by B. Steinberger and an anonymous\nreviewer improved the manuscript. GMT software was used to\nproduce the figures (Wessel and Smith, 1991). This research\nwas supported by NSF-OPP-93-17318. Part of the work was\nperformed at the Jet Propulsion Laboratory, California Institute\nof Technology, under contract to the National Aeronautics and\nSpace Administration. California Institute of Technology,\nDivision of Geological and Planetary Sciences, Contribution\nnumber 8688.", revision_no = "15", abstract = "Major improvements in Late Cretaceous-early Tertiary Pacific-Antarctica\nplate reconstructions, and new East-West Antarctica rotations, allow a more\ndefinitive test of the relative motion between hotspots using global plate circuit\nreconstructions with quantitative uncertainties. The hotspot reconstructions,\nusing an updated Pacific-hotspot kinematic model, display significant misfits of\nobserved and reconstructed hotspot tracks in the Pacific and Indian Oceans.\nThe misfits imply motions of 5-80 mm/yr throughout the Cenozoic between the\nAfrican-Indian hotspot group and the Hawaiian hotspot. Previously recognized\nmisfits between reconstructed Pacific plate paleomagnetic poles and those of\nother plates might be accounted for within the age uncertainty of the\npaleomagnetic poles, and non-dipole field contributions. We conclude that the\nderived motion of the Hawaiian hotspot relative to the Indo-Atlantic hotspots\nbetween 61 Ma and present is a robust result. Thus, the Pacific hotspot\nreference frame cannot be considered as fixed relative to the deep mantle. The\nbend in the Hawaiian-Emperor Seamount chain at 43 Ma resulted from a\nspeedup in the absolute motion of the Pacific plate in a westward direction\nduring a period of southward migration of the hotspot. The relationship between\nthe hotspot motion and plate motion at Hawaii suggests two possible scenarios:\nan entrainment of the volcanic sources in the asthenosphere beneath the rapidly\nmoving plate while the hotspot source drifted in a plate-driven counterflow\ndeeper within the mantle, or drift of the hotspot source which was independent\nof the plate motion, but responded to common forces, producing synchronous\nchanges in hotspot and plate motion during the early Tertiary.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/44994, title ="Mesozoic/Cenozoic Tectonic Events Around Australia", author = "Müller, R. Dietmar and Gaină, Carmen", number = "121", pages = "161-188", month = "January", year = "2000", doi = "10.1029/GM121p0161", isbn = "9780875909790", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140416-154731979", note = "© 2000 American Geophysical Union.\nWe thank John Veevers, Richard Gordon, and\nan anonymous reviewer for constructive comments which improved the quality of the manuscript. This work was supported by the Australian Research Council, the Australian Geological Survey Organization and the\nUniversity of Sydney.", revision_no = "16", abstract = "We use an absolute and relative plate motion model for the plates around\nAustralia to identify major plate tectonic events, evaluate their causes, and investigate\ntheir effects on anomalous intraplate subsidence or uplift and on the history\nof oceanic crustal accretion. An event at ~136 Ma is marked by the onset of sea\nfloor spreading between Greater India and Australia. At about this time long-lived\nsubduction east of Australia ceased, probably due to subduction of the\nPhoenix-Pacific spreading ridge, changing this plate boundary to a transform\nmargin. Between 130 and 80 Ma, Australia and East Antarctica moved eastward\nin the Atlantic-Indian mantle hotspot reference frame. This can be plausibly\nlinked to ridge push from the NW -SE oriented spreading center NW of Australia\nand to the inferred geometry and continued subduction of the Phoenix plate\nbeneath the West Antarctic margin. A drastic change in spreading direction\nbetween the Indian and Australian plates from NE-SW to N-S occurred at about\n99 Ma, possibly caused by a change in absolute motion of the Pacific Plate.\nChron 27 (~61 Ma) marks the onset of relative motion between East and West\nAntarctica, and a change in the relative motion between Australia and Antarctica.\nIt may be linked to the subduction of a segment of the Neo-Tethyan Ridge. Both\nevents caused anomalous subsidence on the Northwest Shelf of Australia. The\nalmost stationary position of Australia w.r.t. the mantle from -80 Ma to -40 Ma\nmay reflect the progressive subduction of the Pacific-Phoenix ridge to the east of\nNew Zealand preceding 80 Ma, resulting in a diminished trench suction force east\nof Australia. Preliminary reconstructions to close the Pacific-Australian plate\ncircuit based on recently collected geophysical data indicate that a tectonic event\nat 43 Ma may mark the onset of renewed subduction east of Australia. At the\nsame time spreading in the Wharton Basin between India and Australia ceased,\nand tectonic reactivation is recorded in the Bass Strait. Excess late Tertiary subsidence\non the northwest shelf of >500 m matches the anomalous depth of the Argo abyssal plain ocean floor. This anomalous subsidence may express largescale\nintraplate deformation in the Indian Ocean. Asymmetries in oceanic crustal\naccretion around Australia are caused mainly by hotspot-ridge and coldspot-ridge\ninteraction.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/45097, title ="Relation of the Puertecitos Volcanic Province, Baja California, Mexico, to development of the plate boundary in the Gulf of California", author = "Stock, Joann M.", number = "334", pages = "143-156", month = "January", year = "2000", doi = "10.1130/0-8137-2334-5.143", isbn = "9780813723341", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140422-074216122", note = "© 2000 Geological Society of America.\nManuscript accepted by the Society August 31, 1998.\nThis research was supported by National Science Foundation\ngrant EAR-9296102. Gary Axen and Paul Umhoefer provided\nhelpful comments on an earlier version of this paper.\nDivision of Geological and Planetary Sciences, California Institute\nof Technology. Contribution 5632.", revision_no = "16", abstract = "The Puertecitos Volcanic Province is a late Miocene and Pliocene ignimbrite field\ncovering an area of ~2600 km^2, with an estimated erupted volume of at least 500 km^3. It\nis unique on the Baja California Peninsula in terms of both its volume and age. It lies at\na 35° bend in the edge of the Gulf of California rift system, at a location where the character\nof the Gulf extensional province, in terms of topography, style of faulting, and\npaleomagnetic rotations, changes dramatically along strike.\nThis chapter presents a speculative model linking the along-strike structural variations\nof the extensional province at this location, and the two major episodes of volcanism\nin the Puertecitos Volcanic Province ca. 6 Ma and 3 Ma, to events in the\nevolution of the spreading and transform system nearby in the Gulf of California. Two\nfracture zone systems project northwestward into the Puertecitos Volcanic Province.\nThe Guaymas transform fault system passes through the Ballenas Channel and is\naligned with the southern boundary of the volcanic province; the Tiburón fracture\nzone (between Isla Tiburón and Isla Angel de la Guarda) projects into the northcentral\npart of the province. The Tiburón fracture zone was important during the\nearly evolution of the Gulf of California. The Guaymas transform fault system was\nmuch shorter during the early evolution of the Gulf of California was only active near\nthe Puertecitos Volcanic Province after 2 Ma. The Tiburón fracture zone may have\nbeen connected to a west-northwest-trending zone of deformation on land, the\nMatomi accommodation zone. Regional field evidence suggests that this accommoda:\ntion zone was active in late Miocene time and may have localized most of the vents for\nthe voluminous ca. 6 Ma volcanism of the northern Puerteci tos Volcanic Province. An\nepisode of 3.3-2.7 Ma volcanism in the extending region is related to a Pliocene jump\nof one Gulf of California spreading center from the Tiburón basin into this area\n(which is now the lower Delfin basin). Continental extension, growth faulting, and\nbasin formation in Pliocene time in the southern part of the Puertecitos Volcanic\nProvince probably preceded this spreading center jump by 1 to 2 m.y.\nThe temporal and spatial aspects of extension in this model may explain the\nstructural transition seen in the Puertecitos region. North of the Puertecitos Volcanic\nProvince, the San Pedro Martir fault and basin and range topography partly reflect\npre-6 Ma extension. Regions to the south, from Puertecitos southward to Gonzaga\nBay, may have been unaffected by extension at this time. The pre-Pliocene rift margin\nprobably passed through the northeast part of the province and southeastward into\nthe Gulf of California, east of Isla Angel de la Guarda. When major deformation began to affect the main part of the volcanic province, the motion in the sector from\nPuertecitos to Gonzaga Bay may have been primarily transform in nature, producing\na very different structural style from that inherited from the earlier transtensional\nhistory in the region north of the Matomi accommodation zone.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/44940, title ="Pacific North America plate tectonics of the Neogene southwestern United States: An update", author = "Atwater, Tanya and Stock, Joann", pages = "393-420", month = "January", year = "1998", isbn = "9780966586909", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140415-074340042", note = "© 1998 Bellwether Pub.\n\nWe thank Brian Wernicke and J. Kent Snow\nfor allowing us to use their results in advance of\npublication. We thank Gene Humphreys, John\nCrowell, Bruce Luyendyk, Craig Nicholson,\nGary Axen, Michael Singer, and Marcy Davis\nfor helpful reviews and Brian Wernicke, Doug\nWilson, Gene Humphreys, Rob Twiss, Bob\nButler, Wayne Thatcher, and Peter Weigand for\nhelpful conversations, advice, and suggestions.\nWe thank the Hall Symposium participants for\nlively feedback and Gary Ernst for his reviews,\nadvice, and patient good humor. This work was\nsupported by NSF Grant EAR-9614674 to J.\nStock. California Institute of Technology, Division\nof Geological and Planetary Sciences, Contribution\nNo. 8534.", revision_no = "14", abstract = "We use updated rotations within the Pacific-Antarctica-Africa-North America plate circuit\nto calculate Pacific-North America plate reconstructions for times since chron 13 (33 Ma). The\ndirection of motion of the Pacific plate relative to stable North America was fairly steady between\nchrons 13 and 4, and then changed and moved in a more northerly direction from chron 4 to the\npresent (8 Ma to the present). No Pliocene changes in Pacific-North America plate motion are\nresolvable in these data, suggesting that Pliocene changes in deformation style along the\nboundary were not driven by changes in plate motion. However, the chron 4 change in\nPacific-North America plate motion appears to correlate very closely to a change in direction of\nextension documented between the Sierra Nevada and the Colorado Plateau. Our best solution\nfor the displacement with respect to stable North America of a point on the Pacific plate that is\nnow near the Mendocino triple junction is that from 30 to 12 Ma the point was displaced along an\nazimuth of ~N60°W at rate of ~33 mm/yr; from 12 Ma to about 8 Ma the azimuth of\ndisplacement was about the same as previously, but the rate was faster (~52 mm/yr); and since 8\nMa the point was displaced along an azimuth of N37°W at a rate of ~52 mm/yr.\nWe compare plate-circuit reconstructions of the edge of the Pacific plate to continental\ndeformation reconstructions of North American tectonic elements across the Basin and Range\nprovince and elsewhere in order to evaluate the relationship of this deformation to the plate\nmotions. The oceanic displacements correspond remarkably well to the continental reconstructions where deformations of the latter have been quantified along a path across the Colorado\nPlateau and central California. They also supply strong constraints for the deformation budgets\nof regions to the north and south, in Cascadia and northern Mexico, respectively.\nWe examine slab-window formation and evolution in a detailed re-analysis of the spreading\ngeometry of the post-Farallon microplates, from 28 to 19 Ma: Development of the slab window\nseems linked to early Miocene volcanism and deformation in the Mojave Desert, although\ndetailed correlations await clarification of early Miocene reconstructions of the Tehachapi\nMountains. We then trace the post-20 Ma motion of the Mendocino slab window edge beneath\nthe Sierran-Great Valley block and find that it drifted steadily north, then stalled just north of\nSutter Buttes at ~4 Ma.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/44943, title ="Pliocene volcanogenic sedimentation along an accommodation zone in northeastern Baja California: The Puertecitos Formation", author = "Martín-Barajas, Arturo and Tellez-Duarte, Miguel", number = "318", pages = "1-24", month = "January", year = "1997", doi = "10.1130/0-8137-2318-3.1 ", isbn = "9780813723181", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140415-080558763", note = "© 1997 Geological Society of America.\n\nManuscript accepted by the Society December 2, 1996.\n\nMartín-Barajas was supported by Consejo Nacional de\nCiencia y Tecnología, México, via grant 1224-T9203. Stock was\nsupported by the Petroleum Research Fund of the American\nChemical Society via grant 21291-G2 and by National Science\nFoundation grant EAR-89-04022. Special thanks to V. Frias for\ndrafting and L. Skerll for improvement of the English usage. We\nthank G. Gastil and R. Sedlock for their constructive review.", revision_no = "18", abstract = "Accommodation zones on rift systems produce distinctive sedimentary facies and\nfacies architecture. The Puertecitos volcanic province in the northern Gulf Extensional\nProvince comprises an accommodation zone and records marine sedimentation\nand explosive volcanism during upper Miocene and early Pliocene time. The\nvolcano-sedimentary sequence consists of two ·westward-thinning, wedge-shaped\ntransgressive-regressive marine sequences, each less than 100 m thick, separated by\none large pyroclastic flow unit. Northward the lower member is separated from the\nupper member by an angular unconformity and/or an interval of subaerial erosion.\nTo the southeast, the volcanic units dominate the stratigraphic sections, whereas\nnorthward the two marine sequences dominate and contain the distal volcaniclastic\nfacies. We propose the name of Puertecitos Formation to formally name this volcanosedimentary\nsequence.\nThe sedimentary facies crop out in subparallel narrow belts along the present\nrange front to the east of the volcanic province. The fossil assemblages and the sedimentary\nfacies show that this area was a tide-dominated marine embayment and\nalluvial plain, deepening to the east. Although the environment is favorable for the\nformation of bioclastic carbonates, the section is essentially devoid of significant carbonate\ndeposits. Instead, the basin was filled with epiclastic and pyroclastic material,\nand individual volcanic units occur as both subaerial and submarine facies and provide\nexcellent chronostratigraphic markers.\nIsostatic sea-level changes and volcaniclastic deposits had a major impact on the\nfacies distribution. Sediment accumulation rates were low. Pre- and postsedimentary\ndeformation was produced by an evenly distributed array of normal faults with small\nindividual offset. This fault pattern produced local facies variations and a distinct\nfacies architecture that contrasts with sedimentary facies associated with basins on\nrift segments to the north and elsewhere in the Gulf Extensional Province, where\nrapid subsidence and coarse-grained deposits are associated with large vertical separation\non basin-bounding faults.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/44873, title ="Early Rift Sedimentation and Structure along the NE Margin of Baja California", author = "Stock, Joann M. and Martín-Barajas, Arturo", pages = "337-371", month = "January", year = "1996", isbn = "1-878861-75-3", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140410-142453767", note = "© 1996 by the Pacific Section American Association of Petroleum Geologists.", revision_no = "18", abstract = "This field trip will examine deposits and structures\nin four basins of NE Baja California which\nformed during Neogene rifting in the Gulf of California\nExtensional Province (Fig. 1). Our objective\nis to provide an overview of depositional environments\nand facies, and tectonic controls on the basin\nevolution, as a guide to interpreting early rift basins\nelsewhere around the Gulf of California as well as at\nother incipient oceanic rifts. The basins we will visit\nrange in age from middle Miocene (the continental\ndeposits of the Santa Rosa basin) to late Miocene\n(upper part of the Santa Rosa basin, and the San\nFelipe marine sequence) to Pliocene (San Felipe\nmarine sequence, Puertecitos Formation, and\nLaguna Salada sequence). They include both marine\nand nonmarine deposits, and record variations\nin sedimentation rate and tectonic patterns that are\nregionally important in the thermal and structural\nevolution of the northern Gulf of California. They\nalso lie in different structural settings within the rift\nsystem.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/50523, title ="Plate Tectonics", author = "Stock, Joann M.", volume = "14", pages = "273-295", month = "January", year = "1996", isbn = "3-527-28136-3", url = "https://resolver.caltech.edu/CaltechAUTHORS:20141020-082122032", note = "© 1996 VCH Publishers, Inc.", revision_no = "12", abstract = "Earthquakes, volcanoes, active faults, and\nmountains tend to occur in long, linear belts\non the Earth's surface, bounding large\nregions that are relatively quiescent. The theory\nof plate tectonics views the quiescent\nregions as rigid \"plates\" and these deformational features, located at the boundaries between\nthe plates, as the inevitable consequences\nof relative motion among the plates.\nSince the plates are confined to the surface\nof a spherical Earth, their relative motion is\ngeometrically constrained. The great power\nof plate-tectonic theory lies in its ability to provide testable kinematic predictions regarding\nthe expected direction and rate of\nmotion at the boundaries between the plates.\nIn addition, it provides a framework for interpreting\npast geological events in terms of\nplate-tectonic processes observable today.\nSection 1 of this article describes the geometrical\naspects of motion of rigid plates on\na sphere, and presents rates and directions\nof motion between major plates, as determined\nfrom the relevant data. Section 2 describes\nthe differences between continental\nand oceanic parts of plates, constraints on\nplate thickness, and the vertical variations of\ntemperature and strength within the plates.\nSection 3 describes the elastic behavior of\nplates, isostasy, and rebound due to viscous\nflow beneath the plates. Section 4 discusses\nplate motions as an indication of processes\nat greater depths in the earth. Finally, Sec. 5\ndiscusses some of the limitations of plate-tectonic\ntheory.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/50496, title ="Estratigrafía y Petrología de la Secuencia Volcánica de Puertecitos, Noreste de Baja California. Transición de un Arco Volcánico a Rift", author = "Martín-Barajas, Arturo and Stock, Joann M.", number = "1", pages = "66-89", month = "January", year = "1993", url = "https://resolver.caltech.edu/CaltechAUTHORS:20141017-131317374", note = "© 1993 Unión Geofísica Mexicana.\n\nEste trabajo se realizó con apoyo del proyecto CONACYT,\nref. 1224-T9203, para el estudio de la Provincia Volcanicá de\nPuertecitos. Gracias a Ramón Mendoza por su colaboración en\nel procesado y en la discusión de los datos estructurales. Gracias\na R. Allmendinger por su programa Faultkin 3.25 y Stereonet 4.3.\nAgradecemos a Hugo Delgado la revisión de una primera versión\ndel manuscrito, y sus comentarios y sugerencias durante el\narbitraje de este trabajo. Gracias a Joan Kimbrough y a Mike\nWalawender (San Diego State University) por las facilidades\npara el análisis por FRX. Gracias a Victor Manuel Frías C. quién\nefectuó el trabajo de edición de dibujos y mapas.", revision_no = "18", abstract = "En la Provincia Volcánica de Puertecitos (PVP), en el NE de Baja California, una sucesión de depósitos\npiroclásticos y lavas riolíticas de la etapa temprana del rift del Golfo de California (Mioceno Tardío-Plioceno)\nsobreyace en discordancia a rocas andesíticas atribuidas al arco volcanico del Mioceno (Tma). En la franja oriental\nde la PVP se han documentado dos períodos de actividad volcánica contemporáneos al desarrollo del rift: uno a\nfines del Mioceno Tardío (ca. 6 Ma) y otro en el Plioceno Temprano (ca. 3 Ma). El primero incluye una secuencia\nde ignimbritas (Tobas El Canelo, Tmec) de más de 300 m de espesor contenida entre dos períodos efusivos de\ndomos riolíticos. Los cambios de espesor de estas ignimbritas (Tmec), indican que su fuente está localizada hacia\nel NW de la zona de estudio, mientras que las coladas riolíticas son locales y forman una serie de domos sobrepuestos\norientados N-S, en la misma dirección del fallamiento. A fines del Plioceno Temprano un segundo período de\nactividad explosiva produjo una serie de flujos piroclásticos de composición riolítica y dacítica (Tpr). Este paquete\nincluye hacia la costa central más de 20 unidades de depósito, con un espesor superior a 200 m que disminuye\nhacia el W y NNE, sugieriendo que la fuente de Tpr se encontraba al E de la costa actual. Hacia el norte, algunas\nunidades de Tpr se hallan interestratificadas con depósitos marinas someros del Plioceno Temprano. Este período\nculminó con la erupción del Volcán Prieto (monogenético) y derrames fisurales de composición andesítica durante\nel Plioceno Tardío y Pleistoceno.\nLas andesitas asociadas al rift en los dos períodos de actividad volcánica son comparativamente de escaso\nvolumen, y se caracterizan por el bajo contenido de K_2O y contenidos variables de TiO_2 y MgO con relación a las\nandesitas y basaltos asociados al arco volcánico del Mioceno. La característica común de las andesitas y las riolitas\nes la asociación clinopiroxeno-ortopiroxeno (y olivino en algunos casos), y bajo o nulo contenido de biotita,\nhornblenda, feldespato alcalino y cuarzo. Lo anterior sugiere una mezcla de magmas, uno máfico a alta temperatura\ny con posible afinidad toleítica, y otro más diferenciado y frio posiblemente formado por material de la corteza.\nLa generación del magmatismo está asociado a la tectónica transtensional, que en el NE de la PVP se manifiesta\ncon una extensión en dirección ESE a ENE durante el Mioceno Tardío - Plioceno.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/49491, title ="Miocene to Holocene Extensional Tectonics and Volcanic Stratigraphy of NE Baja California, Mexico", author = "Stock, Joann M. and Martín, Arturo B.", pages = "44-67", month = "January", year = "1991", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140909-100119572", note = "© 1991 San Diego State University.\n\nJ. Stock's work was supported by\nNational Science Foundation grants EAR-89-04022\nand EAR-90-58217, and by the Petroleum Research\nFund of the American Chemical Society via grant\n21291-G2. The work of Arturo Martín and Francisco\nSuárez was supported by the Secretaria de\nProgramación y Presupuesto de México, and by\nCONACYT (Consejo Nacional de Ciencias y\nTecnología). Part of this work (M. M. Miller) was\ncarried out by the Jet Propulsion Laboratory,\nCalifornia Institute of Technology, under contract with\nthe National Aeronautics and Space Administration.\nThanks to Sandra Zimheld for drafting and\nproofreading, and to Sara Holm for preparation of the\ncamera-ready copy.", revision_no = "14", abstract = "Northeastern Baja California presently experiences\nactive extensional and strike-slip faulting related to the\ntranstensive Pacific-North America plate boundary in\nthe Gulf of California. Some of the active structures\nare fairly new, whereas others appear to have a\nmovement history as far back as Miocene time. This\ntrip focuses on the history of Miocene to Recent\nextension, and its relation to the development of the\nPacific-North America plate boundary, in the Gulf\nExtensional Province of NE Baja California. We will\nsee the extensional structures at the latitudes of San\nFelipe to Puertecitos, and view the stratigraphic\nrelationships of the volcanic and marine rocks that\nconstrain the timing of this extension. Several major\nstructural features are well-exposed here: the Main\nGulf Escarpment and its structural variations along\nstrike; the E-W variations in extensional styles within\nthe extensional province; the extreme narrowing of the\nGulf Extensional Province near El Huerfanito; and\nevidence for variations in timing and amount of\nextension throughout the extensional province.", } @book_section {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/49914, title ="Stress Field at Yucca Mountain, Nevada", author = "Stock, Joann M. and Healy, John H.", number = "1790", pages = "87-93", month = "January", year = "1988", url = "https://resolver.caltech.edu/CaltechAUTHORS:20140922-155549744", note = "© 1988 USGS.\n\nWe thank W.F. Brace, Art McGarr, and Mary Lou\nZoback for helpful comments. Hans Swolfs' suggestions\nwere also much appreciated, although he does not endorse\nall of our conclusions. The field measurements were performed\nin cooperation with the Nevada Operations Office\nof the U.S. Department of Energy under interagency agreement\nDE-AI08-78ET44802. J .M. Stock thanks the Fannie\nand John Hertz Foundation for supporting her graduate work\nat the Massachusetts Institute of Technology, during which\ntime this paper was completed.", revision_no = "11", abstract = "Hydraulic fracturing stress measurements performed in four\nholes (USW G-1, USW G-2, USW G-3, and Ue25P1) indicate\nthat at Yucca Mountain, the least horizontal stress S_h is less than\nthe vertical stress S_v. Values of the greatest horizontal stress S_H\nare intermediate between S_h and S_v, corresponding to a normal\nfaulting regime with values of Φ = (S_H-S_h)/(S_v-S_h) between\n0.25 and 0.7. Drilling-induced hydraulic fractures seen on\nborehole televiewer logs indicate an S_h direction of N. 60° W.\nto N. 65° W. in USW G-1, USW G-2, and USW G-3. The same\nS_h direction is inferred from breakout orientations in USW G-2\nand Ue25P1. The S_h values in the upper parts of the three USW\nG holes are less than the pressure of a column of water filling\nthe borehole to the surface. Thus, the long drilling-induced\nhydraulic fractures in the shallow parts of these holes could have\nbeen formed in attempts to maintain circulation during drilling.\nThese low S_h values may be intimately related to the low water\ntable and fracture-dominated hydrology of Yucca Mountain.", }