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Rockwall slope erosion in the northwestern Himalaya
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  • Elizabeth Orr,
  • Lewis Owen,
  • Sourav Saha,
  • Sarah Hammer,
  • Marc Caffee
Elizabeth Orr
GFZ German Research Center for Geosciences, GFZ German Research Center for Geosciences

Corresponding Author:[email protected]

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Lewis Owen
Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University
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Sourav Saha
Department of Earth, Planetary, and Space Sciences, University of California, Department of Earth, Planetary, and Space Sciences, University of California
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Sarah Hammer
Department of Geology, University of Cincinnati, Department of Geology, University of Cincinnati
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Marc Caffee
Department of Physics, Purdue University, Department of Physics, Purdue University
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Abstract

Rockwall slope erosion is an important component of alpine landscape evolution, yet the role of climate and tectonics in driving this erosion remains unclear. We define the distribution and magnitude of periglacial rockwall slope erosion across 12 catchments in Himachal Pradesh and Jammu and Kashmir in the Himalaya of northern India using cosmogenic 10Be concentrations in sediment from medial moraines. Beryllium-10 concentrations range from 0.5±0.04x104 to 260.0±12.5x104 at/g SiO2, which yield erosion rates between 7.6±1.0 and 0.02±0.04 mm/a. Between ~0.02 and ~8 m of rockwall slope erosion would be possible in this setting across a single millennium, and >2 km when extrapolated for the Quaternary period. This erosion affects catchment sediment flux and glacier dynamics, and helps to establish the pace of topographic change at the headwaters of catchments. We combine rockwall erosion records from the Himalaya of Himachal Pradesh, Jammu and Kashmir and Uttarakhand in India and Baltistan in Pakistan to create a regional erosion dataset. Rockwall slope erosion rates progressively decrease with distance north from the Main Central Thrust and into the interior of the orogen. The distribution and magnitude of this erosion is most closely associated with records of Himalayan denudation and rock uplift, where the highest rates of change are recorded in the Greater Himalaya sequences. This suggests that tectonically driven uplift, rather than climate, is a first order control on patterns of rockwall slope erosion in the northwestern Himalaya. Precipitation and temperature would therefore come as secondary controls.
Feb 2021Published in Journal of Geophysical Research: Earth Surface volume 126 issue 2. 10.1029/2020JF005619