[ { "id": "authors:3vq2g-9xd29", "collection": "authors", "collection_id": "3vq2g-9xd29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170728-143702956", "type": "monograph", "title": "Uranium in granites from the Southwestern United States: actinide parent-daughter systems, sites and mobilization. First year report", "author": [ { "family_name": "Silver", "given_name": "L. T.", "clpid": "Silver-L-T" }, { "family_name": "Williams", "given_name": "I. S.", "clpid": "Williams-I-S" }, { "family_name": "Woodhead", "given_name": "J. A.", "clpid": "Woodhead-J-A" } ], "abstract": "Some of the principal findings of the study on the Lawler Peak Granite are: the granite is dated precisely by this work at 1411 \u00b1 3 m.y., confirming its synchroneity with a great regional terrane of granites. Uranium is presently 8-10 times crustal abundance and thorium 2-3 times in this granite. Uranium is found to be enriched in at least eight, possibly ten, primary igneous mineral species over the whole-rock values. Individual mineral species show distinct levels in, and characteristics ranges of, uranium concentration. It appears that in a uraniferous granite such as this, conventional accuracy mineral suites probably cannot account for most of the uranium in the rock, and more rare, high U-concentration phases also are present and are significant uranium hosts. It appears that at least two different geological episodes have contributed to the disturbance of the U-Th-Pb isotope systems. Studies of various sites for transient dispersal of uranium, thorium, and radiogenic lead isotopes indicate a non-uniform dispersal of these components. It appears that the bulk rock has lost at least 24 percent of its original uranium endowment, accepting limited or no radiogenic lead or thorium migration from the sample.", "publisher": "Caltech Library", "publication_date": "1980-10" }, { "id": "authors:0azx9-sxr15", "collection": "authors", "collection_id": "0azx9-sxr15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220725-222050953", "type": "monograph", "title": "Testimony before the Congressional Committee on Science and Technology. Subcommittee On Energy Research And Production", "author": [ { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" } ], "abstract": "Any analysis of the problems of uranium supply and demand for the United States nuclear power industry must take cognizance of the recent national trauma over the nuclear reactor accident in Three Mile Island, Pennsylvania. National policy decisions on nuclear power will be made with this incident prominently in the foreground. It is essential that a balanced view of all aspects of the availability of energy supplies be maintained during these considerations. \n\nNuclear energy can provide an important supply of electricity for which the true costs must include uncertainties and risks of several kinds. It is clear, also, that no other major source of energy is without some form of significant risk and considerable uncertainty about the timeliness of availability, cost to the immediate environment, and ultimate cost to society. In this discussion, no special advocacy for an enlarged role for nuclear power is intended. It is based upon what I believe to be a reasonable, pragmatic utilization of the present large investments in nuclear energy power systems with all appropriate care in the face of a growing world energy shortage. \n\nPerceptions of the requirements of natural uranium for the United States nuclear power industry have undergone significant modification in the last few years. The Department of Energy has continued to reduce its projections of installed nuclear generating capacity from year to year, as shown in Table 1.", "publisher": "Caltech Library", "publication_date": "1979-05-31" }, { "id": "authors:05681-g7165", "collection": "authors", "collection_id": "05681-g7165", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220718-375642500", "type": "monograph", "title": "Plumbotectonics IIA, Precambrian massive sulfide deposits", "author": [ { "family_name": "Stacey", "given_name": "J. S.", "clpid": "Stacey-J-S" }, { "family_name": "Doe", "given_name": "B. R.", "clpid": "Doe-B-R" }, { "family_name": "Silver", "given_name": "L. T.", "clpid": "Silver-L-T" }, { "family_name": "Zartman", "given_name": "R. E.", "clpid": "Zartman-R-E" } ], "abstract": "Professor Tugarinov has long recognized the importance of common lead in rocks and ore deposits as an age indicator. The paper he authored with L. K. Gavrilova and V. P. Bedrinov in 1963, and the work of Cantanzaro and Gast (1960), are two of the most extensive studies of the evolution of lead isotopes in feldspars. Such studies are very important to our understanding of crustal evolution because of our ability to calibrate feldspar ages by other means. The pioneer paper by Stanton and Russell (1959) opened the way for dating certain deposits submarine volcanic exhalative massive sulfide deposits in the orogene. It is now generally accepted that these deposits formed during volcanism or shortly thereafter (Hutchinson, 1973). Therefore their lead isotope evolution may be correlated with time by dating the enclosing rocks. Over the last eight years, investigators have gradually realized that lead isotopic analyses, coupled with geochronologic studies, may yield much additional information about ore deposits and their origins. \n\nThis paper evaluates the lead isotopic characteristics of Precambrian massive sulfide deposits of all types. The treatment here will be similar to that used by Doe and Zartman (1976) in their \"plumbotectonics\" model for Phanerozoic deposits of this type. The submarine volcanic exhalative ores were chosen for emphasis because they are the type class for \"conformable\" or \"stratiform\" leads used in lead isotope model theory. We suggest that any deviation from a strictly average isotopic composition for a given age of deposit can often be explained by differences in the tectonic settings in which the ores were formed. This paper is a \"state-of-knowledge\" discussion of that thesis.", "doi": "10.3133/ofr76476", "publisher": "U.S. Geological Survey", "publication_date": "1976" }, { "id": "authors:fyxbe-3m314", "collection": "authors", "collection_id": "fyxbe-3m314", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151027-140622202", "type": "monograph", "title": "Skylab-4 visual observations project: Geological features of southwestern North America", "author": [ { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" }, { "family_name": "Anderson", "given_name": "T. H.", "clpid": "Anderson-T-H" }, { "family_name": "Conway", "given_name": "C. M.", "clpid": "Conway-C-M" }, { "family_name": "Murray", "given_name": "J. D.", "clpid": "Murray-J-D" }, { "family_name": "Powell", "given_name": "R. E.", "clpid": "Powell-R-E" } ], "contributor": [ { "family_name": "Carr", "given_name": "G. P.", "clpid": "Carr-Gerald-P" }, { "family_name": "Gibson", "given_name": "E. G.", "clpid": "Gibson-Edward-G" }, { "family_name": "Pogue", "given_name": "W. R.", "clpid": "Pogue-William-R" } ], "abstract": "Visual observations conducted by Skylab-4 crewmen on seven designated geological target areas and other targets of opportunity in parts of southwestern United States and northwestern Mexico were described. The experiments were designed to learn how effectively geologic features could be observed from orbit and what research information could be obtained from the observations when supported by ground studies. For the limited preparation they received, the crewmen demonstrated exceptional observational ability and produced outstanding photographic studies. They also formulated cogent opinions on how to improve future observational and photo-documentation techniques. From the photographs and other observations, it was possible to obtain significant research contributions to on-going field investigations. These contributions were integrated into other aspects of the ground investigations to the following topics: major faults, regional stratigraphy, occurrence of Precambrian crystalline rocks, mapping of Mesozoic volcanic rocks, regional geology.", "publisher": "California Institute of Technology", "publication_date": "1975-11-01" }, { "id": "authors:8rj4j-a4385", "collection": "authors", "collection_id": "8rj4j-a4385", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220728-152248486", "type": "monograph", "title": "Revision of Precambrian stratigraphy in the Prescott-Jerome area, Yavapai County, Arizona", "author": [ { "family_name": "Anderson", "given_name": "C. A.", "clpid": "Anderson-Charles-Alfred" }, { "family_name": "Blacet", "given_name": "P. M.", "clpid": "Blacet-P-M" }, { "family_name": "Silver", "given_name": "L. T.", "clpid": "Silver-L-T" }, { "family_name": "Stern", "given_name": "T. W.", "clpid": "Stern-T-W" } ], "abstract": "The metamorphosed volcanic, volcaniclastic, and sedimentary rocks that predate the oldest plutonic rocks in the Prescott-Jerome area (1,770\u00b110 m.y.) are placed in the Yavapai Series, a provincial time-stratigraphic term denned as the 'time interval from 1,770\u00b110 to 1,820+m.y. Two rock-stratigraphic groups are recognized; the Ash Creek Group is1 separated from the Big Bug Group by a major fault and a large pluton of quartz diorite. Isotopic dating now indicates that the Ash Creek Group is older. The name Big Bug Group replaces the term Alder Group, used in earlier publications on the Prescott-Jerome area. \n\nWithin the Big Bug Group the Indian Hills' Volcanics and Green Gulch Volcanites have been shown to be the same formation, and the latter term is retained. Where first described the Chaparral Volcanics was bounded by faults, but subsequent mapping has demonstrated that it occupies the upper part of the Spud Mountain Volcanics; so the term Chaparral Volcanics is abandoned. The Texas Gulch Formation is removed from the Yavapai Series because it is separated from the rocks of the Big Bug Group by a period of plutonism, represented by the Brady Butte Granodiorite, and subsequent erosion.", "doi": "10.3133/b1324C", "publisher": "United States Geological Survey", "publication_date": "1971" }, { "id": "authors:8ra4s-jzn62", "collection": "authors", "collection_id": "8ra4s-jzn62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220801-90018200", "type": "monograph", "title": "Geology and ore deposits of the Dragoon quadrangle, Cochise County, Arizona", "author": [ { "family_name": "Cooper", "given_name": "John R.", "clpid": "Cooper-John-Roberts" }, { "family_name": "Silver", "given_name": "Leon T.", "clpid": "Silver-L-T" } ], "abstract": "The area described in this report is in Cochise County in southeastern Arizona and comprises a little more than 250 square miles in the northwestern part of the county. The mining district known as Johnson Camp is near the center of the area, and the village of Dragoon on the Southern Pacific Railroad is near the southeastern corner. \n\nThe area is in the Mexican Highland section of the Basin and Range province and straddles the divide between the San Pedro valley on the west and the Sulphur Spring valley on the east. \n\nThe Little Dragoon Mountains in the south-central part of the area constitute the principal topographic feature. In the eastern part are the north tip of the Dragoon Mountains, the Gunnison Hills, the Steele Hills, and the south tip of the Winchester Mountains. In the west-central part are the Johnny Lyon Hills, from which a ridge extends northward and joins the Galiuro Mountains north of the area described. \n\nThe rock formations of the area range in age from Precambrian to Recent. The oldest rocks are moderately metamorphosed graywackcs, slates, and lava flows that make up the Pinal schist of early Precambrian age. Also early Precambrian are rhyolite porphyry intrusive sheets and stocks, a large granodiorite mass in the Johnny Lyon Hills, and granite exposed at the south end of the Winchester Mountains. The Tungsten King granite and associated aplite on the west side of the Little Dragoon Mountains, and granite exposed at the north end of the Dragoon Mountains are also referred to the early Precambrian but could be younger. \n\nUpper Precambrian rocks, generally unmetamorphosed, include the Scanlan conglomerate, Pioneer shale, Barnes conglomerate, and Dripping Spring quartzite which are part of the Apache group; extensive diabase sills of Precambrian age were intruded into these rocks.", "doi": "10.3133/pp416", "publisher": "United States Geological Survey", "publication_date": "1964" } ]