Climate-controlled distribution of erosion over the Himalaya in the late Quaternary: Evidence from Sr-Nd isotope variability in paleo-Yamuna channel sediments

Abstract

Over the millennial timescales, climate controls erosion rates and erosional fluxes in the Himalaya. However, the role of climate, particularly the strength of the Indian summer monsoon (ISM) and Himalayan glacial cover, on the distribution of erosion over the Himalaya is poorly understood. This study presents detrital radiogenic Sr-Nd isotope compositions in two ∼48 m long cores representing sediment deposition in a paleo-Yamuna River channel, northwest India (Haryana), since marine isotope stage (MIS) 4. ⁸⁷Sr/⁸⁶Sr (0.7342–0.8066) and ε_Nd (−14.0 to −19.7) values exhibit significant down-core variabilities and reveal varying proportions of sediments derived from the Higher and Lesser Himalayan sources. The down-core profiles show higher ⁸⁷Sr/⁸⁶Sr and lower ε_Nd during MIS 4, mid-MIS 3, and last glacial maximum in MIS 2, which indicate reduced contribution of sediments from the Higher Himalaya during cold and arid periods typified by weaker ISM precipitation and increased glacial cover over the Himalaya. Further, the paleo-Yamuna record and a few available records on the Himalayan-derived sediments suggest that variations in local geology, topography, and location of the focused precipitation in a catchment could also influence erosion distribution.