Steady 10Be‐derived paleoerosion rates across the Plio‐Pleistocene climate transition, Fish Creek‐Vallecito basin, California

• Published in: Journal of geophysical research. Earth surface 2017-09, Vol.122 (9), p.1653-1677
• Main Authors: Oskin, M. E., Longinotti, N. E., Peryam, T. C., Dorsey, R. J., DeBoer, C. J., Housen, B. A., Blisniuk, K. D.
• Format: Article
• Language: English
• Subjects: Aridity; Beryllium 10; California; Catchment area; Climate; Climate change; Climate effects; Climate variations; Coastal inlets; cosmogenic nuclides; Creeks; Erosion; Erosion rates; Evolution; Fish; Gaging; Global climate; Landscape; Lithology; Mountains; paleoerosion rate; Pleistocene; Pliocene; Salton Trough; Sediment; Sedimentary rocks; Stratigraphy; Uplift
• ISSN: 2169-9003; 2169-9011
• DOI: 10.1002/2016JF004113

Rates of erosion over time provide a valuable tool for gauging tectonic and climatic drivers of landscape evolution. Here we measure 10Be 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 10Be signal. We find that paleoerosion rates were remarkably consistent between 1 and 4 Ma, averaging 38 ± 24 m/Myr (2σ). 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. Key Points 10Be‐derived paleoerosion rates are measured from fluvial sedimentary rocks No change in erosion rate of eastern Peninsular Range, California, detected from 4 Ma to 1 Ma Plio‐Pleistocene climate change had no clear effect on erosion rates in this nonglaciated setting