Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2350
The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism
The thick sequence of Miocene lava flows exposed on Steens Mountain in southeastern Oregon is well known for containing a detailed record of a reversed‐to‐normal geomagnetic polarity transition. Paleomagnetic samples were obtained from the sequence for a combined study of the directional and intensity variations recorded; the paleointensity study is reported in a companion paper. This effort has r
Authors
Edward A. Mankinen, M. Prevot, C. Sherman Grommé, Robert S. Coe
The Steens Mountain (Oregon) geomagnetic polarity transition, 2. Field intensity variations and discussion of reversal models
We carried out an extensive paleointensity study of the 15.5±0.3 m.y. Miocene reversed‐to‐normal polarity transition recorded in lava flows from Steens Mountain (south central Oregon). One hundred eighty‐five samples from the collection whose paleodirectional study is reported by Mankinen et al. (this issue) were chosen for paleointensity investigations because of their low viscosity index, high C
Authors
M. Prevot, Edward A. Mankinen, Robert S. Coe, C. Sherman Grommé
Petrology and tectonic significance of augen gneiss from a belt of Mississippian granitoids in the Yukon-Tanana terrane, east- central Alaska
An approximately E-W-trending belt of porphyritic peraluminous granitic rocks, metamorphosed and deformed to augen gneiss, is exposed for 400 km across the Yukon-Tanana terrain. Chemical, textural, and isotopic data from large augen-gneiss bodies indicate that these bodies originated as early Mississippian granitic rocks that assimilated, or were anatectically derived from, early Proterozoic crust
Authors
Cynthia Dusel-Bacon, John N. Aleinikoff
Bibliography of United States landslide maps and reports
No abstract available.
Authors
C.S. Alger, E. E. Brabb
In situ stress, natural fracture distribution, and borehole elongation in the Auburn Geothermal Well, Auburn, New York
Hydraulic fracturing stress measurements and a borehole televiewer survey were conducted in a 1.6‐km‐deep well at Auburn, New York. This well, which was drilled at the outer margin of the Appalachian Fold and Thrust Belt in the Appalachian Plateau, penetrates approximately 1540 m of lower Paleozoic sedimentary rocks and terminates 60 m into the Precambrian marble basement. Analysis of the hydrauli
Authors
Stephen H. Hickman, John H. Healy, Mark D. Zoback
Well bore breakouts and in situ stress
The detailed cross-sectional shape of stress induced well bore breakouts has been studied using specially processed ultrasonic borehole televiewer data. Breakout shapes are shown for a variety of rock types and introduce a simple elastic failure model which explains many features of the observations. Both the observations and calculations indicate that the breakouts define relatively broad and fla
Authors
Mark D. Zoback, Daniel Moos, Larry Mastin, Roger N. Anderson
Innovative approaches to landslide hazard and risk mapping
No abstract available.
Authors
E. E. Brabb
Correlation of metamorphosed Paleozoic strata of the southeastern Mojave Desert region, California and Arizona: Discussion and reply
No abstract available.
Authors
H.J. Brown, Paul Stone, Keith A. Howard, Warren Hamilton
Geology of the Ruby Mountains-East Humboldt Range, Nevada: A Cordilleran metamorphic core complex
No abstract available.
Authors
A.W. Snoke, Keith A. Howard
Canyon-filling lavas and lava dams on the Boise River, Idaho, and their significance for evaluating downcutting during the last 2 million years
Basalts that periodically dammed the Boise River and its South Fork over the last 2 million years reveal the canyon history and illustrate how lava interacted with impounded river water. Intracanyon basalt flows record a granite canyon successively filled by lava and then recut at least five times in the last 2 million years. The most voluminous flow, Steamboat Rock Basalt, reached 60 kilometers d
Authors
Keith A. Howard, John W. Shervais, E. H. McKee
Statistical relations among earthquake magnitude, surface rupture length, and surface fault displacement
In order to refine correlations of surface-wave magnitude, fault rupture length at the ground surface, and fault displacement at the surface by including the uncertainties in these variables, the existing data were critically reviewed and a new data base was compiled. Earthquake magnitudes were redetermined as necessary to make them as consistent as possible with the Gutenberg methods and results,
Authors
Manuel G. Bonilla, Robert K. Mark, James J. Lienkaemper
Preaccretion and postaccretion plutonic belts in allochtonous terrane of the Klamath Mountains, California and Oregon
No abstract available.
Authors
W. P. Irwin