Sedimentary response to eocene tectonic rotation in western Oregon
Abstract
Published paleomagnetic studies have shown that the Oregon Coast Range s rotated 60 degrees clockwise since middle Eocene time, probably by pivoting either during collision of a seamount terrane or during an episode of asymmetric extension within western North America. Eocene sedimentary deposits within the Oregon Coast Range basin, in particular the Tyee Formation, document changes in basin evolution that provide geologic constraints for proposed rotation models. The Tyee Formation comprises an arkosic petrofacies which is different from underlying lithic sandstones that were derived from the adjacent Klamath Mountains. Isotopic study of sandstones of the arkosic petrofacies, including Sm-Nd, Rb-Sr, K-Ar, and O 18 analyses indicate that much of the sandstone was not derived from the Klamath Mountains or nearby Sierra Nevada. The source area most likely included S-type granites of the Idaho Batholith.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1983
- Bibcode:
- 1983PhDT........21H
- Keywords:
-
- Oregon;
- Plates (Tectonics);
- Rotation;
- Sedimentary Rocks;
- Paleomagnetism;
- Radioactive Age Determination;
- Structural Properties (Geology);
- Geophysics