Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2494
Models of grades and tonnages of some lode tin deposits Models of grades and tonnages of some lode tin deposits
Descriptive and grade/tonnage models have recently been built for many types of deposits. Such models consist of descriptions of mineralogy, host rocks, ore textures, controls, alteration, geochemical signatures, age, and tectonic settings, together with statistical models of grades, tonnages, and contained metal of deposits of each type. The models are used to identify areas that may...
Authors
W. D. Menzie, B.L. Reed, Donald A. Singer
Paleomagnetic results from the Shasta Bally Plutonic Belt in the Klamath Mountains Province, northern California Paleomagnetic results from the Shasta Bally Plutonic Belt in the Klamath Mountains Province, northern California
Available paleomagnetic data show approximately 100° of clockwise rotation for Permian and Triassic strata of the Eastern Klamath terrane. Jurassic strata of this terrane are rotated approximately 60° clockwise, which is comparable to rotations reported for Jurassic plutons that occur elsewhere in the Klamath Mountains province. Paleomagnetic data obtained during the present study from...
Authors
Edward A. Mankinen, William P. Irwin, C. Sherman Gromme
Mineral resource assessment of the Wiseman 1° by 3° quadrangle, Alaska Mineral resource assessment of the Wiseman 1° by 3° quadrangle, Alaska
No abstract available.
Authors
James D. Bliss, W. P. Brosge, J. T. Dillon, J.T. Dutro, J. B. Cathrall, J. W. Cady
The relative contribution of accretion, shear, and extension to Cenozoic tectonic rotation in the Pacific Northwest The relative contribution of accretion, shear, and extension to Cenozoic tectonic rotation in the Pacific Northwest
Large Cenozoic clockwise rotations defined by paleomagnetic data are an established fact in the Pacific Northwest, and many tectonic models have been proposed to explain them, including (1) rotation of accreted oceanic microplates during docking, (2) dextral shear between North America and northward-moving oceanic plates to the west, and (3) microplate rotation in front of an expanding...
Authors
Ray E. Wells, Paul L. Heller
Reconnaissance geologic map of the Pilot Creek Quadrangle, Humboldt and Trinity counties, California Reconnaissance geologic map of the Pilot Creek Quadrangle, Humboldt and Trinity counties, California
No abstract available.
Authors
K. R. Aalto, William Porter Irwin, H.M. Kelsey
Climate and ephemeral-stream processes: Twentieth-century geomorphology and alluvial stratigraphy of the Little Colorado River, Arizona Climate and ephemeral-stream processes: Twentieth-century geomorphology and alluvial stratigraphy of the Little Colorado River, Arizona
During the first 40 years of the twentieth century, erosion was the dominant geomorphic process affecting the morphology of the Little Colorado River channel. The discharge regimen was one of frequent large floods and high annual discharge that created a wide sandy channel free of vegetation. In the 1940s and early 1950s, average annual precipitation declined, reducing annual discharge...
Authors
Richard Hereford
Neogene stratigraphy, foraminifera, diatoms, and depositional history of Maria Madre Island, Mexico: Evidence of early Neogene marine conditions in the southern Gulf of California Neogene stratigraphy, foraminifera, diatoms, and depositional history of Maria Madre Island, Mexico: Evidence of early Neogene marine conditions in the southern Gulf of California
Foraminifera and diatoms have been analyzed from an upper Miocene through Pleistocene(?) sequence of marine sediments exposed on Maria Madre Island, largest of the Trés Marias Islands off the Pacific coast of Mexico. The Neogene stratigraphic sequence exposed on Maria Madre Island includes a mid-Miocene(?) non-marine and/or shallow marine sandstone unconformably overlain by a lower upper...
Authors
C. McCloy, J.C. Ingle, J.A. Barron
Vitrinite reflectance and illite crystallinity, Franciscan central belt and Yolla Bolly terrane, northern California Vitrinite reflectance and illite crystallinity, Franciscan central belt and Yolla Bolly terrane, northern California
No abstract available.
Authors
M.B. Underwood, R.H. Strong, M.C. Blake
Preliminary geologic map of the Monkeys Head Quadrangle, Mohave and La Paz counties, Arizona Preliminary geologic map of the Monkeys Head Quadrangle, Mohave and La Paz counties, Arizona
No abstract available.
Authors
David R. Sherrod
Geologic map and structure sections of the Loma Prieta 7 1/2' quadrangle, Santa Clara and Santa Cruz Counties, California Geologic map and structure sections of the Loma Prieta 7 1/2' quadrangle, Santa Clara and Santa Cruz Counties, California
No abstract available.
Authors
Robert J. McLaughlin, Joseph C. Clark, Earl E. Brabb
Crustal extension along a rooted system of imbricate low-angle faults: Colorado River extensional corridor, California and Arizona Crustal extension along a rooted system of imbricate low-angle faults: Colorado River extensional corridor, California and Arizona
The upper 10 to 15 km of crystalline crust in the 100-km-wide Colorado River extensional corridor of mid-Tertiary age underwent extension along an imbricate system of gently dipping normal faults. Detachment faults cut gently down-section eastward in the direction of tectonic transport from a headwall breakaway, best expressed in the Old Woman Mountains, California. Successively higher...
Authors
Keith A. Howard, B.E. John
Thermal maturity of tectonostratigraphic terranes within the Franciscan Complex, California Thermal maturity of tectonostratigraphic terranes within the Franciscan Complex, California
Indicators of organic metamorphism provide valuable tools for analyzing the thermal history of tectonostratigraphic terranes. Paleotemperature estimates derived from vitrinite reflectance, for example, are more precise than values based upon inorganic mineral assemblages in low‐grade rocks. Isothermal geometries must be interpreted within the context of structural and stratigraphic data...
Authors
M.B. Underwood, M. Clark Blake, D. G. Howell