SPATIAL PATTERNS OF 10BE-BASED CATCHMENT WIDE DENUDATION IN THE WESTERN PANAMINT MOUNTAINS, CALIFORNIA

Erosion rates are a key control of landscape evolution in mountains and the sediment supply to adjacent basins. The rate of erosion in mountains varies spatially due to several factors most notably tectonic uplift, precipitation, surface processes, and landslides. To better understand the controls on erosion in extensional mountains; here, we explore the spatial variability of catchment wide denudation (chemical + mechanical weathering) along strike in the Western Panamint Mountains.

Catchment wide denudation rates are quantified by measuring ¹⁰Be concentrations in quartz sand sourced from the entire catchment, and collected at catchment outlets. We calculate the average denudation rates of nine additional catchments and compare the results to basin metrics including climate, precipitation, basin relief (as a product of tectonic uplift along the range), maximum elevation, and mean basin elevation. Measured denudation rates range from 0.23 - 0.012 mm/yr, the rates correlate most strongly to catchment relief. Erosion rates increase spatially from south to north along the southern to Central Panamint Mountains. Our ¹⁰Be-based estimates are similar to previous fan-volume based estimates of Quaternary denudation in Panamint Valley.

We hypothesize there is a gradient of uplift increasing in a south to north trend that corresponds to the resulting rates of erosion. Thus, we speculate tectonics are the first-order control on erosion in the Panamint Mountains. Future work is necessary to clarify potential relationships between lithology and erosion rate, including a more comprehensive geomorphic analysis of each basin with respect to spatial patterns of erosion.