Coastal tectonics on the eastern margin of the Pacific Rim: late Quaternary sea-level history and uplift rates, Channel Islands National Park, California, USA

QUATERNARY SCIENCE REVIEWS

卷:105

Article

Muhs, Daniel R.¹  Simmons, Kathleen R.¹  Schumann, R. Randall¹  Groves, Lindsey T.²  DeVogel, Stephen B.³  Minor, Scott A.¹  Laurel, DeAnna⁴ 

[1] US Geol Survey, Fed Ctr, Denver, CO 80225 USA

[2] Nat Hist Museum Los Angeles Cty, Sect Malacol, Los Angeles, CA 90007 USA

[3] Univ Colorado, Inst Arctic & Alpine Res, Amino Acid Geochronol Lab, Boulder, CO 80309 USA

[4] Colorado State Univ, Dept Geosci, Ft Collins, CO 80523 USA

关键词: Marine terraces;    Uplift rates;    Sea-level history;    Channel Islands;    California;    Uranium-series dating;    Aminostratigraphy;    Glacial-isostatic adjustment processes;    Tectonics;    Pacific Rim;   

DOI  :  10.1016/j.quascirev.2014.09.017

来源: Elsevier

【 摘 要 】

The Pacific Rim is a region where tectonic processes play a significant role in coastal landscape evolution. Coastal California, on the eastern margin of the Pacific Rim, is very active tectonically and geomorphic expressions of this include uplifted marine terraces. There have been, however, conflicting estimates of the rate of late Quaternary uplift of marine terraces in coastal California, particularly for the northern Channel Islands. In the present study, the terraces on San Miguel Island and Santa Rosa Island were mapped and new age estimates were generated using uranium-series dating of fossil corals and amino acid geochronology of fossil mollusks. Results indicate that the 2nd terrace on both islands is similar to 120 ka and the 1st terrace on Santa Rosa Island is similar to 80 ka. These ages correspond to two global high-sea stands of the Last Interglacial complex, marine isotope stages (MIS) 5.5 and 5.1, respectively. The age estimates indicate that San Miguel Island and Santa Rosa Island have been tectonically uplifted at rates of 0.12-0.20 m/ka in the late Quaternary, similar to uplift rates inferred from previous studies on neighboring Santa Cruz Island. The newly estimated uplift rates for the northern Channel Islands are, however, an order of magnitude lower than a recent study that generated uplift rates from an offshore terrace dating to the Last Glacial period. The differences between the estimated uplift rates in the present study and the offshore study are explained by the magnitude of glacial isostatic adjustment (GIA) effects that were not known at the time of the earlier study. Set in the larger context of northeastern Pacific Rim tectonics, Channel Islands uplift rates are higher than those coastal localities on the margin of the East Pacific Rise spreading center, but slightly lower than those of most localities adjacent to the Cascadia subduction zone. The uplift rates reported here for the northern Channel Islands are similar to those reported for most other localities where strike-slip tectonics are dominant, but lower than localities where restraining bends (such as the Big Bend of the San Andreas Fault) result in crustal shortening. Published by Elsevier Ltd.

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