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Paleomagnetic rotations and the Cenozoic tectonics of the Cascade Arc, Washington, Oregon, and California

Journal of Geophysical Research

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Abstract

Paleomagnetic results from Cenozoic (62-12 Ma) volcanic rocks of the Cascade Arc and adjacent areas indicate that moderate to large clockwise rotations are an important component of the tectonic history of the arc, Two mechanisms of rotation are suggested. The progressive increase in rotation toward the coast in arc and forearc rocks results from distributed dextral shear, which is likely driven by oblique subduction of oceanic plates to the west. Simple shear rotation is accommodated in the upper crust by strike-slip faulting. A progressive eastward shift of the arc volcanic front with time in the rotated arc terrane is the result of the westward pivoting of the arc block in front of a zone of extension since Eocene time. Westward migration of bimodal Basin and Range volcanism since at least 16 Ma is tracking rotation of the frontal arc block and growth of the Basin and Range in its wake. -from Author

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Paleomagnetic rotations and the Cenozoic tectonics of the Cascade Arc, Washington, Oregon, and California
Series title:
Journal of Geophysical Research
Volume
95
Issue:
B12
Year Published:
1990
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research