Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2383
Geology of a subduction complex in the Franciscan assemblage of northern California
No abstract available.
Authors
M. Clark Blake, A. S. Jayko, D. G. Howell
A geologic reconnaissance of the Cycladic blueschist belt, Greece
The Cycladic blueschist belt consists of two distinctive segments separated by a broad zone of superposed granitic and high-temperature metamorphic rocks. The northern segment contains early metamorphic fold axes and parallel glaucophane lineations that trend ∼060° with a progressive increase in metamorphism toward the southeast. The southern segment contains similar fold axes and glaucophane line
Authors
M. Clark Blake, Michel Bonneau, Jacques Geyssant, J.R. Kienast, Claude Lepvrier, Henri Maluski, Dimitrios Papanikolaou
The Franciscan assemblage and related rocks in northern California: A reinterpretation
No abstract available.
Geologic transect of the northern Diablo Range, California
No abstract available.
Authors
M. Clark Blake
Proterozoic zircon from augen gneiss, Yukon-Tanana Upland, east-central Alaska
U-Th-Pb analyses of zircons from an ortho-augen gneiss body in the Yukon-Tanana Upland of east-central Alaska yield strong evidence for the presence of early Proterozoic material in this area. U-Pb data define a chord that intersects concordia at about 2,300 and 345 m.y. We consider two interpretations: (1) the protolith was intruded during the Proterozoic and was subsequently metamorphosed in the
Authors
John N. Aleinikoff, Cynthia Dusel-Bacon, Helen L. Foster, Kiyoto Futa
Geologic setting, petrology, and geochemistry of zoned tungsten-bearing skarns at the Strawberry Mine, central Sierra Nevada, California
The Strawberry mine, 90 km northeast of Fresno, California, occurs on the margin of a small roof pendant of Early Jurassic metasedimentary rocks and middle Cretaceous metaigneous rocks. Middle Cretaceous granitic intrusions surround and intrude the roof pendant. Adjacent to one granodiorite intrusion, several subvertical marble layers are replaced by scheelite-bearing skarns. The skarns form spear
Authors
Warren J. Nokleberg
Petrographic and chemical characteristics of pyrite-marcasite mineralization in hole 465A, southern Hess Rise
Core recovered from Hess Rise contains concentrations of pyrite, marcasite, and barite in the lowermost meter of limestone (Unit II) and in the brecciated upper part of the underlying volcanic basement (Unit HI). Petrographic and chemical data indicate that the sulfide-barite assemblage in the limestone is mainly a product of low-temperature diagenetic processes. The iron-sulfide phases are biogen
Authors
Randolph A. Koski, James R. Hein
Reconnaissance geologic map of the Topaz Lake 15 minute quadrangle, California and Nevada, with Quaternary geology
No abstract available.
Authors
David John, James Giusso, W. J. Moore, R. A. Armin, J. C. Dohrenwend
Regenerate faults of small Cenozoic offset as probable earthquake sources in the southeastern United States
No abstract available.
Authors
Carl M. Wentworth, Marcia Mergner-Keefer
Physical factors that could restrict mineral supply
Stages in the metal supply process are affected by each of the following physical (geologic) factors: (1) geographic distribution of concentrations of potential ore minerals, (2) depth of these concentrations, (3) mineralogy, (4) grain size of the minerals, and (5) grade and (6) tonnages of the concentrations. For mineral deposits of each type in each geologic and political environment, the lowest
Authors
John H. DeYoung, Donald A. Singer