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Measuring vertical tectonic motion at the intersection of the Santa Cruz-Catalina Ridge and northern Channel Islands platform, California continental borderland, using submerged paleoshorelines

Jason D. Chaytor, Chris Goldfinger, Melissa A. Meiner, Gary J. Huftile, Christopher G. Romsos and Mark R. Legg
Measuring vertical tectonic motion at the intersection of the Santa Cruz-Catalina Ridge and northern Channel Islands platform, California continental borderland, using submerged paleoshorelines
Geological Society of America Bulletin (August 2008) 120 (7-8): 1053-1071

Abstract

We used submerged paleoshorelines as strain markers to investigate Holocene and late Pleistocene vertical tectonic movement at the intersection of the offshore Santa Cruz-Catalina Ridge with the southern boundary of the Western Transverse Ranges, within the California Continental Borderland. Past submerged shoreline positions were identified using high-resolution multibeam bathymetry, side-scan sonar, submersible observations, and the presence of intertidal and subtidal invertebrate fossils. Numerous accelerator mass spectrometry (AMS) (super 14) C ages of shells from these paleoshorelines were found to be between approximately 27,000 yr radiocarbon (RC) and 11,500 yr before present, indicative of shoreline colonization during and following the Last Glacial Maximum (LGM), establishing these paleoshorelines as a usable datum for measuring vertical change since this time. Removal of the nontectonic component of vertical change using an ice-volume-equivalent eustatic sea-level compilation indicates between 20 and 45 m of uplift of the eastern part of the Northern Channel Islands block since the LGM lowstand, resulting in an uplift rate of 1.50+ or -0.59 mm/yr over the last 23 k.y. This rate closely matches uplift predicted by published slip rates for the Channel Islands thrust, which underlies the Northern Channel Islands platform. Results from post-LGM shoreline features on Pilgrim Banks are somewhat more ambiguous. Submarine paleoshoreline uplift, together with the extensive upper-crustal fold-thrust style of deformation, illustrates the transpressional interaction of the Borderland and the Western Transverse Ranges blocks where the Santa Cruz-Catalina Ridge and northern Channel Islands intersect.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 120
Serial Issue: 7-8
Title: Measuring vertical tectonic motion at the intersection of the Santa Cruz-Catalina Ridge and northern Channel Islands platform, California continental borderland, using submerged paleoshorelines
Affiliation: Oregon State University, College of Oceanic and Atmospheric Sciences, Corvallis, OR, United States
Pages: 1053-1071
Published: 200808
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 100
Accession Number: 2008-104178
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch maps
N33°00'00" - N34°19'60", W120°30'00" - W118°00'00"
Secondary Affiliation: Queensland University of Technology, AUS, AustraliaLegg Geophysical, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200836
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