OCB - Mass Wasting & Tectonics

CCB_Structures2024

SR2303 was a U.C. Ship Funds funded cruise with the objective of mapping and sampling the Catalina Crater and Emory Knoll from February to March 2023. The high-resolution swath bathymetry and sub-bottom data obtained on this cruise suggests the Catalina Crater to be a potential volcanic structure. Both bathymetric and sub-bottom stratigraphy data show evidence for a series of northwest striking, left-stepping faults through the eastern section on the Catalina Crater mote. Rock samples dredged from the central plateau show clear evidence of a subaerial eruption which contradicts previous interpretations of this structure. Additionally, samples dredged from Emory Knoll were also volcanic contradicting previous interpretation of this as a tectonically controlled “pop-up” structure. Preliminary geochemical analysis of these samples show they are a trachyandesite composition and have broadly similar trace element patterns to volcanic rocks from Santa Cruz Island. These results could have a profound impact for the interpretation of California Borderland evolution as well as elucidating a previously unknown geohazard for Southern California. We propose to complete the survey of the Catalina Crater rim and continue the sampling campaign along the Catalina Crater walls and Emory Knoll if time permits.