Neogene rotations and quasicontinuous deformation of the Pacific Northwest continental margin

Geology
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Abstract

Paleomagnetically determined rotations about vertical axes of 15 to 12 Ma flows of the Miocene Columbia River Basalt Group of Oregon and Washington decrease smoothly with distance from the plate margin, consistent with a simple physical model for continental deformation that assumes the lithosphere behaves as a thin layer of fluid. The average rate of northward translation of the continental margin since 15 Ma calculated from the rotations, using this model, is about 15 mm/yr, which suggests that much of the tangential motion between the Juan de Fuca and North American plates since middle Miocene time has been taken up by deformation of North America. The fluid-like character of the large-scale deformation implies that the brittle upper crust follows the motions of the deeper parts of the lithosphere.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Neogene rotations and quasicontinuous deformation of the Pacific Northwest continental margin
Series title Geology
DOI 10.1130/0091-7613(1991)019<0978:NRAQDO>2.3.CO;2
Volume 19
Issue 10
Year Published 1991
Language English
Publisher Geological Survey of America
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 4 p.
First page 978
Last page 981