ALBERT

Description: Abstract

Description: These datasets were used to evaluate the main controls on last ~6 million years erosion rate variability of the northwestern Himalaya. The Earth’s climate has been cooling during the last ~15 million years and started fluctuating between cold and warm periods since ~2-3 million years ago. Many researchers think that these long-term climatic changes were accompanied by changes in continental erosion. However, quantifying erosion rates in the geological past is challenging, and previous studies reached contrasting conclusions. In this study, we quantified erosion rates in the north-western Indian Himalaya over the past 6 million years by measuring in situ-produced cosmogenic 10Be in exhumed older foreland basin sediments. The 10Be is produced by cosmic rays in minerals at the Earth's surface, and its abundance indicates erosion rates. Our reconstructed erosion rates show a quasi-cyclic pattern with a periodicity of ~1 million year and a gradual increase towards the present. We suggest that both patterns—cyclicity and gradual increase—are unrelated to climatic changes. Instead, we propose that the growth of the Himalaya by repeatedly scraping off rocks from the Indian plate (basal accretion), resulted in changes of its topography that were accompanied by changes in erosion rates. In this scenario, basal accretion episodically changes rock-uplift patterns, which brings landscapes out of equilibrium and results in quasi-cyclic variations in erosion rates. We used numerical landscape evolution simulations to demonstrate that this hypothesis is physically plausible. Datasets provided here includes summary of the location, depositional age, and stratigraphic position of 41 Siwalik sandstone samples collected from the Haripur section in Himachal Pradesh, India (Dataset S1); 10Be analysis results of Siwalik samples (2021-006_Mandal-et-al_Dataset-S1); sample location and 10Be analysis results of modern river sands from the Yamuna River and its tributaries near the Dehradun Basin (2021-006_Mandal-et-al_Dataset-S2); input parameters for the calculation of paleoerosion rates (2021-006_Mandal-et-al_Dataset-S3); and reconstructed 10Be paleoconcentrations and paleoerosion rates (Dataset S4). Moreover, the data include a compilation of published magnetostratigraphy-derived sediment accumulation rates in the late Cenozoic Himalayan foreland basin (2021-006_Mandal-et-al_Dataset-S5). We also include a movie (2021-006_Mandal-et-al_Movie-S1) that is a complete numerical landscape evolution model run with four consecutive accretion cycles of equal magnitude. For more information (for e.g., sampling method, analytical procedure, and data processing) please refer to the associated data description file and the main article (Mandal et al., 2021).