Quantifying the response of rapidly eroding landscapes to climate change with cosmogenic nuclides
Mineralogy, Petrology and Geochemistry
Final Report Abstract
The research in this project suggests that Himalayan erosion rates did not change by much during past phases of valley aggradation. Through high-resolution sampling and by distinguishing sediment 10 provenance through lithology, we were able to show that the lower Be concentrations in terrace sands, which could be interpreted as higher paleo-erosion rates, are most likely a result of a relative increase in subglacial-derived sediments during the last glacial cycle, when the valley-fill aggraded. This result contradicts previous suggestions, which related the valley aggradation to higher erosion rates across the Himalaya. Although subglacial erosion rates likely increased during periods when glaciers were more extended, it is not entirely clear whether these were also higher compared to erosion rates in unglaciated parts of the catchment. In consequence, our research supports the idea that erosion in the Himalaya is dominantly controlled by tectonic uplift rates and that temporal changes in monsoon precipitation exert minor influence on erosion rates. Be-derived erosion rates in the terrace sediments are surprisingly similar. Previous studies by the PI as well as other researchers have raised the possibility that 10Be-derived erosion rates from rapidly eroding landscapes can be quite variable due to the influence of landslides and other locally-sourced sediment pulses. However, our results suggest that such variability is rather small, which is good news for reconstructing erosion rates in such environments.
Publications
- (2019): Multiproxy isotopic and geochemical analysis of the Siwalik sediments in NW India: implication for the Late Cenozoic tectonic evolution of the Himalaya. Tectonics, vol. 38(1), p. 120-143
Mandal, S.K., Scherler, D., Romer, R.L., Burg, J.-P., Guillong, M., Schleicher, A.M.
(See online at https://doi.org/10.1029/2018TC005200) - (2020): Glacial influence on late Pleistocene Be-derived paleo-erosion rates in the north-western Himalaya, India. Earth and Planetary Science Letters, vol. 547
Kapannusch, R., Scherler, D., King, G., Wittmann, H.
(See online at https://doi.org/10.1016/j.epsl.2020.116441)
