Recent advancements in geochronology, geologic mapping, and landslide characterization in basement rocks of the San Gabriel Mountains block
Published:May 18, 2020
Jonathan A. Nourse, Brian J. Swanson, Alexander D. Lusk, Nicolas C. Barth, Joshua J. Schwartz, Karissa B. Vermillion, 2020. "Recent advancements in geochronology, geologic mapping, and landslide characterization in basement rocks of the San Gabriel Mountains block", From the Islands to the Mountains: A 2020 View of Geologic Excursions in Southern California, Richard V. Heermance, Joshua J. Schwartz
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This field trip examines Paleoproterozoic basement, Neoproterozoic metasedimentary strata, and crosscutting Mesozoic intrusive rocks at Frazier Mountain, Placerita Canyon, and Limerock Canyon in the western San Gabriel Mountains block, California. We present new U-Pb zircon geochronology results that constrain the Proterozoic through Cretaceous tectonic and magmatic history. The excursion ends in San Antonio Canyon in the eastern San Gabriel Mountains where several large rock avalanche deposits are sourced from distinct basement rocks. 10Be surface exposure ages and post-infrared infrared stimulated luminescence burial ages demonstrate late Pleistocene to Holocene movements for these landslides.
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From the Islands to the Mountains: A 2020 View of Geologic Excursions in Southern California
This volume includes five geologic field-trip guides in the Los Angeles region associated with the 2020 GSA Cordilleran Section Meeting that was scheduled for May 2020, in Pasadena, California. The guides are organized in a generally counterclockwise order around the Los Angeles Basin. The first guide by Burgette et al. provides new slip rates, age constraints, and observations of the active Sierra Madre fault zone that borders the northern side of the San Gabriel and San Fernando Valleys. The Nourse et al. guide takes a new look at the San Gabriel Mountains from a basement and geomorphologic perspective. Further west, Keller et al. provide one of the first published field-trip guides focused on the 9 January 2018 Montecito debris flows that caused 23 deaths. The volume then moves south to Santa Cruz Island, where Davis et al. provide an updated review of the island’s geology within the California borderlands. The final guide returns to the east, where Platt et al. present the unique geology of Santa Catalina Island with a focus on the subduction-related Catalina Schist.