Paleodischarge of the Mojave River, southwestern U.S.A, investigated with single-pebble measurements of 10Be
Geosphere
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Abstract
The paleohydrology of ephemeral stream systems is an important constraint on paleoclimatic conditions in arid environments, but remains difficult to constrain quantitatively. For example, sedimentary records of the size and extent of pluvial lakes in the Mojave Desert have been used as a proxy for Quaternary climate variability. Although the delivery mechanisms of this additional water are still being debated, it is generally agreed that the discharge of the Mojave River, which supplied water for several Pleistocene pluvial lakes along its course, must have been significantly greater during lake high stands. We used the 10Be concentrations of 10 individual quartzite pebbles sourced from the San Bernardino Mountains and collected from a ~25 ka strath terrace of the Mojave River near Barstow, Calif., to test whether pebble ages record the timing of large paleodischarge of the Mojave River. Our exposure ages indicate that periods of discharge large enough to transport pebble-sized sediment occurred at least four times over the past ~240 ky; individual pebble ages cluster into four groups with exposure ages of 24.82 ± 2.52 ka (n=3), 55.79 ± 2.59 ka (n=2), 99.14 ± 6.04 ka (n=4) and 239.9 ± 52.16 ka (n=1). These inferred large discharge events occurred during both glacial and interglacial conditions. We demonstrate that bedload materials provide information about the frequency and duration of transport events in river systems. This approach could be further improved with the addition of additional measurements of one or more cosmogenic nuclides coupled with models of river discharge and pebble transport.
Suggested Citation
Cyr, A.J., Miller, D., Mahan, S.A., 2015, Paleodischarge of the Mojave River, southwestern U.S.A, investigated with single-pebble measurements of 10Be: Geosphere, v. 11, no. 4, p. 1158-1171, https://doi.org/10.1130/GES01134.1.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Paleodischarge of the Mojave River, southwestern U.S.A, investigated with single-pebble measurements of 10Be |
| Series title | Geosphere |
| DOI | 10.1130/GES01134.1 |
| Volume | 11 |
| Issue | 4 |
| Publication Date | July 15, 2015 |
| Year Published | 2015 |
| Language | English |
| Publisher | Geological Society of America |
| Contributing office(s) | Geology, Minerals, Energy, and Geophysics Science Center |
| Description | 14 p. |
| First page | 1158 |
| Last page | 1171 |