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Publications

Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center

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Well bore breakouts and in situ stress 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...
Authors
Mark D. Zoback, Daniel Moos, Larry Mastin, Roger N. Anderson

The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism 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...
Authors
Edward A. Mankinen, M. Prevot, C. Sherman Gromme, Robert S. Coe

In situ stress, natural fracture distribution, and borehole elongation in the Auburn Geothermal Well, Auburn, New York 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...
Authors
Stephen H. Hickman, John H. Healy, Mark D. Zoback

Canyon-filling lavas and lava dams on the Boise River, Idaho, and their significance for evaluating downcutting during the last 2 million years 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...
Authors
Keith A. Howard, John W. Shervais, E.H. McKee
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