Dissertation/Thesis Abstract

Miocene Rotation of Santa Catalina Island: Implications for the Southern California Continental Borderland
by Stewart, Ryan A., M.S., California State University, Long Beach, 2019, 113; 13862788
Abstract (Summary)

Santa Catalina Island (SCI) sits offshore of Palos Verdes Peninsula (PVP) within the Southern California Continental Borderland (SCCB). Paleomagnetic data suggests that SCI and PVP rotated approximately 90° clockwise since the early Miocene during the same tectonic episode that rotated and translated the Western Transverse Range into its present-day location. A more recent paleomagnetic study on PVP, indicated little to no rotation . PVP and SCI share similar geology, so an updated paleomagnetic study on SCI was needed to address the possibility of a similar discrepancy.

The goals of this project were to test the results of the previous study and to generate a more robust dataset for SCI. This is significant because paleomagnetic data from offshore SCCB are sparse when compared to the data from onshore and the Northern Channel Islands and are needed to test models of the tectonic development of this part of California. In this study, samples were collected from 13 sites on SCI and subjected to both thermal and step-wise alternating field demagnetization for analysis. Corrected equal area plots and Fischer distributions for sampled flows and dikes revealed significant differences: 20-17 Ma andesitic flows show approximately 90° of rotation while the more recently injected porphyritic and basaltic dikes show no significant rotation. The results of this study provide previously unknown timing constraints on rotation within the SCCB and hold implications for models of this rotation.

Indexing (document details)
Advisor: Onderdonk, Nathaniel W.
Commitee: Francis, Robert D., Holk, Gregory J.
School: California State University, Long Beach
Department: Geological Sciences
School Location: United States -- California
Source: MAI 81/1(E), Masters Abstracts International
Subjects: Geology
Publication Number: 13862788
ISBN: 9781085574754
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