Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2354
U–Pb geochronology of Late Cretaceous and early Tertiary plutons in the northern Coast Mountains batholith
U–Pb geochronologic studies demonstrate that steeply dipping, sheetlike tonalitic plutons along the western margin of the northern Coast Mountains batholith were emplaced between ~83 and ~57 (perhaps ~55) Ma. Less elongate tonalitic–granodioritic bodies in central portions of the batholith yield ages of 59–58 Ma, coeval with younger phases of the tonalitic sheets. Large granite–granodiorite bodies
Authors
G.E. Gehrels, W. C. McClelland, S.D. Sampson, Patchett P. Jonathan, David A. Brew
Off-fault ground ruptures in the Santa Cruz Mountains, California: Ridge-top spreading versus tectonic extension during the 1989 Loma Prieta earthquake
The Ms 7.1 Loma Prieta earthquake of 18 October 1989 produced abundant ground ruptures in an 8 by 4 km area along Summit Road and Skyland Ridge in the Santa Cruz Mountains. Predominantly extensional fissures formed a left-stepping, crudely en echelon pattern along ridges of the hanging-wall block southwest of the San Andreas fault, about 12 km northwest of the epicenter. The fissures are subparall
Authors
Daniel J. Ponti, Ray E. Wells
Application of the FINDER system to the search for epithermal vein gold-silver deposits : Kushikino, Japan, a case study
The FINDER system employs geometric probability, Bayesian statistics, and the normal probability density function to integrate spatial and frequency information to produce a map of probabilities of target centers. Target centers can be mineral deposits, alteration associated with mineral deposits, or any other target that can be represented by a regular shape on a two dimensional map. The size, sh
Authors
Donald A. Singer, Ryoichi Kouda
Mineralization patterns in time and space in the Great Basin of Nevada
No abstract available.
Authors
Dennis P. Cox, Steve Ludington, M.G. Sherlock, Donald A. Singer
Neogene rotations and quasicontinuous deformation of the Pacific Northwest continental margin
Paleomagnetically determined rotations about vertical axes of 15 to 12 Ma flows of the Miocene Columbia River Basalt Group of Oregon and Washington decrease smoothly with distance from the plate margin, consistent with a simple physical model for continental deformation that assumes the lithosphere behaves as a thin layer of fluid. The average rate of northward translation of the continental margi
Authors
Philip England, Ray E. Wells
ALACARTE installation and system manual
ALACARTE offers a convenient way to compile geologic maps in the computer as spatial databases that can be used to prepare both cartographic images and analytic derivatives.
It is a menu-controlled shell, organized in geologic terms, that provides on-screen control of the program ARC/INFO, a commercial geographic information system (GIS).
Input can be from imported scans, digitizer tracing, or on-
Authors
Todd T. Fitzgibbon
ALACARTE User Interface - AML Code and Demonstration Maps
ALACARTE offers a convenient way to compile geologic maps in the computer as spatial databases that can be used to prepare both cartographic images and analytic derivatives.
It is a menu-controlled shell, organized in geologic terms, that provides on-screen control of the program ARC/INFO, a commercial geographic information system (GIS).
Input can be from imported scans, digitizer tracing, or on-
Authors
Todd T. Fitzgibbon, Carl M. Wentworth
Metamorphic facies map of southeastern Alaska – Distribution, facies, and ages of regionally metamorphosed rocks
No abstract available.
Authors
Cynthia Dusel-Bacon, D. A. Brew, S. L. Douglass
Factors affecting the recognition of faults exposed in exploratory trenches
Trenching-a widely used method for evaluating fault activity-has limitations that can mislead investigators. Some segments of fault strands in trench walls may not be visible, and this nonvisibility can lead to incorrect interpretations of time of most recent displacement and recurrence intervals on a fault. We examined the logs of 163 trench exposures and tabulated data on more than 1,200 fault s
Authors
Manuel G. Bonilla, James J. Lienkaemper
Landform classification of New Mexico by computer
No abstract available.
Authors
Richard Dikau, Earl E. Brabb, Robert M. Mark