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Wrench faults, pull‐apart basins, and volcanism in central Oregon: A new tectonic model based on image interpretation
Author(s) -
Gutmanis J. C.
Publication year - 1989
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3350240303
Subject(s) - geology , fault (geology) , impact crater , tectonics , sinistral and dextral , seismology , structural basin , wrench , volcanism , volcano , quaternary , echelon formation , volcanic rock , extensional definition , basin and range topography , basin and range province , paleontology , mechanical engineering , physics , astronomy , engineering
A tectonic study of the Newberry Crater region of central Oregon has been based on the interpretation of Landsat Thematic Mapper imagery. Two major faults, the Brothers‐Tumalo and Eugene‐Denio Faults, pass NW‐SE through the region and step to the right at the eastern margin of the Cascades Range. Dextral wrench faulting on these structures during the Tertiary controlled the formation of the La Pine Basin, a pull‐apart structure containing Tertiary and Quaternary sediments and volcanics. Tertiary wrench faulting appears to have been associated with rotations of crustal blocks at a plate margin, but was superseded in the Quaternary by extensional faulting of the Basin and Range province. Newberry Crater and other major bimodal volcanic centres in the NW Cordillera (Crater Lake, Medicine Lake, Mt. St. Helens) seem to have a similar tectonic setting in crustal pull‐aparts. A relationship between magma type and fault trend at Newberry and Medicine Lake is suggested.