Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2482
Geochronology of augen gneiss and related rocks, Yukon-Tanana terrane, east-central Alaska Geochronology of augen gneiss and related rocks, Yukon-Tanana terrane, east-central Alaska
Using several isotopic techniques, we have determined the ages of selected metamorphic rocks in the Yukon-Tanana terrane (YTT) of east-central Alaska. U-Pb zircon data from an augen gneiss body in the Big Delta quadrangle indicate that the granitoid protolith of the gneiss was intruded 341 ± 3 m.y. ago (lower intercept age). An upper intercept age of 2,136 ± 31 m.y. indicates an...
Authors
John N. Aleinikoff, Cynthia Dusel-Bacon, Helen L. Foster
Paleomagnetism of the Tertiary Clarno Formation of central Oregon and its significance for the tectonic history of the Pacific Northwest Paleomagnetism of the Tertiary Clarno Formation of central Oregon and its significance for the tectonic history of the Pacific Northwest
The Clarno Formation, a mostly Eocene and partly early Oligocene sequence of andesitic lavas and volcaniclastic rocks, is the oldest Tertiary formation exposed in north central Oregon. Remanent magnetization directions at 46 sites in the lavas provide a paleomagnetic pole at 84°N, 278°E with a 95% confidence cone of 7°. Comparison of this pole with the North American reference pole for...
Authors
C. Sherman Gromme, Myrl E. Beck, Ray E. Wells, David C. Engebretson
Map showing the status of landslide inventory and susceptibility mapping in California Map showing the status of landslide inventory and susceptibility mapping in California
No abstract available.
Authors
Fred Taylor, E. E. Brabb
By
Geology, Energy, and Minerals Mission Area, Natural Hazards Mission Area, Energy Resources Program, Landslide Hazards Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Geologic Hazards Science Center, Geology, Minerals, Energy, and Geophysics Science Center
Geophysics: A reversal of geomagnetic polarity Geophysics: A reversal of geomagnetic polarity
The detailed behaviour of the geomagnetic field during reversals is documented by palaeomagnetists to constrain models of the geomagnetic dynamo. Reversals are studied by measuring the magnetic remanence preserved in rocks to obtain both the direction and intensity of the ancient magnetic field.
Authors
Edward A. Mankinen
By
Paleomagnetism and K-Ar ages of volcanic rocks from Long Valley caldera, California Paleomagnetism and K-Ar ages of volcanic rocks from Long Valley caldera, California
Paleomagnetic measurements and K‐Ar age determinations on volcanic rocks from Long Valley caldera, California, have enabled further refinement of eruptive activity within this large silicic volcanic center. K‐Ar age determinations show that postcaldera volcanic eruptions began 0.73 m.y. ago and continued periodically until about 50,000 years ago. The eruptions were not temporally random...
Authors
Edward A. Mankinen, C. Sherman Gromme, G. Brent Dalrymple, Marvin A. Lanphere, Roy A. Bailey
Southern hemisphere origin of the Cretaceous Laytonville Limestone of California Southern hemisphere origin of the Cretaceous Laytonville Limestone of California
New paleomagnetic, paleontologic, and stratigraphic data from outcrops of the Laytonville Limestone (101 to 88 million years old) support a Southern Hemisphere orgin. A paleomagnetic megaconglomerate test is statistically significant and suggests magnetization at 14?? ?? 5?? south, predating Late Cretaceous to Eocene (70 to 50 million years ago) accretion. Rapid Kula plate movement or...
Authors
J.A. Tarduno, M. McWilliams, W.V. Sliter, H. E. Cook, M.C. Blake, I. Premoli-Silva
Preliminary geologic map of Santa Cruz County, California Preliminary geologic map of Santa Cruz County, California
No abstract available.
Authors
Earl E. Brabb
Relationship of grade, tonnage, and basement lithology in volcanic-hosted epithermal precious-and base-metal quartz-adularia-type districts Relationship of grade, tonnage, and basement lithology in volcanic-hosted epithermal precious-and base-metal quartz-adularia-type districts
Examination of grades, tonnages, and basement rocks for 88 epithermal precious- and base-metal quartz-adularia-type districts in North, Central, and South America, and Japan reveals that the type of basement rock below the mineralized veins is useful for predicting grade and size of deposits. Epithermal districts overlying basement with salt and evaporites, or rocks with trapped sea...
Authors
D.L. Mosier, Donald A. Singer, T. Sato, N.J. Page
Tectonostratigraphic terranes in southwest Oregon Tectonostratigraphic terranes in southwest Oregon
No abstract available.
Authors
Blake, D.E. Engebretson, A. S. Jayko, J. L. Jones
Tectonostratigraphic terranes of northern California Tectonostratigraphic terranes of northern California
No abstract available.
Authors
M. Clark Blake, A. S. Jayko, R. J. McLaughlin
Book Review: The Encyclopedia for Applied Geology Book Review: The Encyclopedia for Applied Geology
No abstract available.
Authors
E. E. Brabb
On the line: Losing by a landslide, invited comment On the line: Losing by a landslide, invited comment
No abstract available.
Authors
E. E. Brabb
By
Geology, Energy, and Minerals Mission Area, Natural Hazards Mission Area, Energy Resources Program, Landslide Hazards Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Geologic Hazards Science Center, Geology, Minerals, Energy, and Geophysics Science Center