Date of Award

2026-05-01

Degree Name

Master of Science

Department

Geological Sciences

Advisor(s)

Jason W. Ricketts

Abstract

Southeastern California has experienced a complex recent geologic history as it continues to evolve from a convergent boundary to a period of NE-directed extension and evolution of the Eastern California Shear Zone (ECSZ). This transition is recorded in exhumed bodies of Pelona-Orocopia-Rand (POR) schist and in changing styles of fault deformation. This thesis has two interrelated goals. First, I aim to refine the timing of transition from NE extension to NS contraction in the ECSZ of southeastern California by integrating (U-Th)/He thermochronology with field-based structural analysis. The second prong of this study is to constrain broader patterns of POR schist exhumation through (U-Th)/He thermochronology to compare to regional models of formation. Fault kinematic results in <23 Ma and <9 Ma volcanic rocks and Bear Canyon conglomerate in southeastern California predominantly preserve evidence for EW extension through multiple modes of faulting. None of these deposits preserves strong evidence for NE extension, supporting models that the ECSZ initiated >10 Ma in the study area. Zircon (U-Th)/He thermochronologic data from POR schist exposures suggest that each locality preserves a unique exhumational history, where some locations were exhumed in a single pulse and others may have experienced multiple periods of diachronous exhumation. The earlier pulses in exhumation may be related to a combination of subduction channel processes, buoyancy forces, and/or tectonic slivering. The younger pulses in exhumation can be more closely tied to Neogene faults and tectonic extension.

Language

en

Provenance

Received from ProQuest

File Size

93 p.

File Format

application/pdf

Rights Holder

James Boyette Barker

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Geology Commons

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