USING DEM ANALYSIS TO EVALUATE THE ROLE OF BEDROCK LITHOLOGY ON PERSISTENCE OF GEOMORPHIC FEATURES RELATED TO LARGE-SCALE, MIOCENE TO HOLOCENE LANDSLIDES IN NEVADA

Long-lived tectonism in Nevada has resulted in abundant large-scale (deposits covering >1 km²) landslide events throughout the state. Many of these features are relatively recent; related to Basin and Range and Walker Lane tectonism. Some landslide deposits are older, related to caldera collapse events, metamorphic core complexes, and Paleozoic-Mesozoic tectonism. For features that are post-Basin and Range initiation (mid Miocene-recent), it is unclear how lithology influences geomorphic expression of landsliding events nor how long evidence of landslide events persists in range fronts. Though landslide scarps may erode quickly, drainage networks within catchments and range crest sinuosity may retain the imprint of large-scale landsliding for a prolonged period of time.

In order to evaluate the influence of lithology and longevity of landslide headwall features, we conducted DEM analyses on nine groups of landslides from a variety of lithologies and ages in Nevada. These include individual landslides and landslide complexes in the Carson Range (granite, basalt, andesite, volcaniclastic rocks, 18 Quaternary landslides), the Hays Canyon Range (basalt and tuff; 11 Quaternary landslides), the Summit Lake area (rhyolite, tuff, and basalt; 9 Quaternary, 1 Mio-Pliocene landslides), the Jarbidge area (rhyolite and ash-flow tuff; 5 Quaternary landslides), Spruce Mountain (Paleozoic carbonate; 3 Quaternary landslides), Silver Peak (basalt, andesite, rhyolite, tuff, phyllite, quartz monzonite, limestone; 15 Quaternary landslides), Delamar Mountains (ash-flow tuff; 14 Late Miocene-Pleistocene landslides), Bare Mountain (Paleozoic carbonate; 2 Miocene landslides), and the Sheep Range (Paleozoic carbonate; 5 Miocene landslides). For each area we performed analysis on 10 m DEMs using a set of scripts coded in MATLAB. Analyses were calculated using the full area containing the landslides and compared with the landslide deposits. In MATLAB, we calculated geomorphic quantities, including roughness, aspect ratio, curvature, slope, and hilltop curvature. Interpretation of these data is on-going. These data will lead to a better understanding on how bedrock lithology and landslide activity can interact to affect the overall morphology of mountain ranges in Nevada.