Sponsor
Portland State University. Department of Geology
First Advisor
Michael L. Cummings
Date of Publication
1986
Document Type
Thesis
Degree Name
Master of Science (M.S.) in Geology
Department
Geology
Language
English
Subjects
Geology -- Oregon -- Bear Creek Butte Region, Hydrothermal deposits -- Oregon -- Bear Creek Butte Region, Mineralogy -- Oregon -- Bear Creek Butte Region
DOI
10.15760/etd.5542
Physical Description
1 online resource (140 p.)
Abstract
The Eocene Clarno Formation, the Oligocene John Day Formation and basalts of the High Lava Plains are exposed in the Bear Creek Butte area in Central Oregon. In this area the Clarno Formation can be divided into a lower sequence composed of intermediate lava flows with intercalated mudflows and volcaniclastic sediments and an upper sequence of rhyolite and basalt flows and felsic ruffs. Separating the two units is a well developed saprolite. The change from intermediate to rhyolite-basalt volcanism reflects a change in the tectonic environment of the Cascade volcanic arc from compression to relaxation as subduction of the Farallon plate by the North American plate slowed, allowing extension of the continental plate margin to occur.
Rights
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
Persistent Identifier
http://archives.pdx.edu/ds/psu/20642
Recommended Citation
Wilkening, Richard Matthew, "The geology and hydrothermal alteration of the Bear Creek Butte area, Crook County, central Oregon" (1986). Dissertations and Theses. Paper 3656.
https://doi.org/10.15760/etd.5542
Plate 1
wilkening plate 1b.jpg (1232 kB)
Plate 1b
wilkening plate 2.jpg (2019 kB)
Plate 2
wilkening plate 2b.jpg (1221 kB)
Plate 2b
Comments
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