Graduation Date
Fall 2021
Document Type
Thesis
Program
Master of Science degree with a major in Environmental Systems, option Geology
Committee Chair Name
Dr. Melanie Michalak
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Dr. Susan Cashman
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Dr. Mark Hemphill-Haley
Third Committee Member Affiliation
HSU Faculty or Staff
Keywords
Geology, Thermochronology, Tectonics
Subject Categories
Geology
Abstract
The Klamath Mountains Province (KMP), located at the southern end of the forearc of the Cascadia Subduction Zone, displays a distinct topographic and geologic signature. Compared to the forearc in the north, the KMP comprises Paleozoic-Mesozoic basement rocks with relatively high modern elevation and relief. This study investigates the pattern of rock cooling in the KMP by using thermochronology on plutons exhumed by faults and plutons outside of mapped faults. In this study, I target three regions in the KMP: the Ashland pluton offset by the Siskiyou Summit fault in the northeast KMP, the Grayback pluton in the northwest KMP, and the China Creek pluton offset by the Browns Meadow fault in the southern KMP. Zircon (ZHe) and apatite (AHe) (U-Th)/He ages from these plutons record post emplacement cooling during the late Early Cretaceous and tectonic exhumation during the late Oligocene to early Miocene. Cooling ages from this study are compiled with available thermochronologic data to identify spatial and temporal patterns of exhumation. This comparison shows a late Oligocene to early Miocene cooling signal throughout the KMP, with the exception of a geographic cluster of late Eocene to early Oligocene AHe ages found in the south-central core of the KMP. This cluster of older cooling ages is bound by the Browns Meadow fault and La Grange fault, indicating Tertiary faulting influenced exhumation in the southern KMP. However, the pervasive late Oligocene to early Miocene cooling signal suggests regional erosion is a more important factor influencing rock cooling than previously thought.
Citation Style
GSA
Recommended Citation
Team, Taylor C., "Structural and thermochronologic evidence of Paleogene-Neogene faulting and exhumation of the Klamath mountain province" (2021). Cal Poly Humboldt theses and projects. 520.
https://digitalcommons.humboldt.edu/etd/520