Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2350
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 contain undi
Authors
W. D. Menzie, B.L. Reed, Donald A. Singer
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 Basin and R
Authors
Ray E. Wells, Paul L. Heller
Integrating spatial and frequency information in the search for kuroko deposits of the Hokuroku District, Japan
A new method (FINDER) that uses the area of influence and Bayesian statistics to aid in selection of target areas on the basis of one or more variables and multiple observations was tested with drill hole data. A previously defined bimodal distribution of Na 2 O with the low sodium group confined to a 1.5 X 3.0-km zone beneath the cluster of deposits at Fukazawa was used as a control area for one
Authors
Donald A. Singer, Ryoichi Kouda
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 the Shasta
Authors
Edward A. Mankinen, William P. Irwin, C. Sherman Grommé
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
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
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 to about 57
Authors
Richard Hereford
Mineral resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas, Lake County, Oregon
No abstract available.
Authors
William J. Keith, Harley D. King, Mark E. Gettings, Fredrick L. Johnson
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
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 and more di
Authors
Keith A. Howard, B.E. John
Metamorphic core complexes, Mesozoic ductile thrusts, and Cenozoic detachments: Old Woman Mountains: Chemehuevi Mountains transect, California and Arizona
No abstract available.
Authors
Keith A. Howard, B.E. John, C. F. Miller
Comment and reply on "Correlation of the Peach Springs Tuff, a large-volume Miocene ignimbrite sheet in California and Arizona"
No abstract available.
Authors
S.K. Mittwede, A. F. Glazner, Keith A. Howard, D. M. Miller