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Steady 10 Be‐derived paleoerosion rates across the Plio‐Pleistocene climate transition, Fish Creek‐Vallecito basin, California
Author(s) -
Oskin M. E.,
Longinotti N. E.,
Peryam T. C.,
Dorsey R. J.,
DeBoer C. J.,
Housen B. A.,
Blisniuk K. D.
Publication year - 2017
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
eISSN - 2169-9011
pISSN - 2169-9003
DOI - 10.1002/2016jf004113
Subject(s) - plio pleistocene , structural basin , geology , erosion , drainage basin , arid , climate change , lithology , pleistocene , sediment , paleontology , physical geography , fluvial , oceanography , geography , cartography
Rates of erosion over time provide a valuable tool for gauging tectonic and climatic drivers of landscape evolution. Here we measure 10 Be archived in quartz sediment from the Fish Creek‐Vallecito basin to resolve a time series of catchment‐averaged erosion rates and to test the hypothesis that aridity and increased climate variation after approximately 3 Ma led to an increase in erosion rates in this semiarid, ice‐free setting. The Fish Creek‐Vallecito basin, located east of the Peninsular Ranges in Southern California, is an ideal setting to derive a Plio‐Pleistocene paleoerosion rate record. The basin has a rapid sediment accumulation rate, a detailed magnetostratigraphic age record, and its stratigraphy has been exposed through recent, rapid uplift and erosion. A well‐defined source region of uniform lithology and low erosion rate provides a high, reproducible 10 Be signal. We find that paleoerosion rates were remarkably consistent between 1 and 4 Ma, averaging 38 ± 24 m/Myr (2 σ ). Modern catchment‐averaged erosion rates are similar to the paleoerosion rates. The uniformity of erosion over the past 4 Myr indicates that the landscape was not significantly affected by late Pliocene global climate change, nor was it affected by a local long‐term increase in aridity.