Because of the multi-stepped pathways of sediment comprising the foreland fold-thrust belt (FFTB), detrital quartz grains that recycle from the FFTB sources contain cosmogenic radionuclides (CRN), such as 10^Be and 26^Al, accumulated during previous exposure, resulting in inheritance and, hence, anomalously low erosion rates. This inhibits the straightforward use of 10^Be as tracers for modern erosion rates and sediment discharge from the FFTB, prevalent at the external edges of collisional orogens such as the Himalaya. We present a novel approach for quantifying the erosion rates of FFTB by comparing measured and modeled CRN concentrations in fluvial sediments. We apply this approach to the Mohand Range, an emergent fault-related fold in the frontal part of the northwestern Himalaya (see the location map below). The 10^Be and 26^Al datasets presented here were used to calibrate our model, which we used to quantify the erosion rates in and sediment flux from the Mohand Range.
Datasets provided here include a summary of the location and depositional age of 33 fluvial sediments and two sandstone samples collected from the Mohand Range, 10^Be analysis results of 23 of these fluvial sediments and two bedrock samples, and 26^Al-10^Be pair analysis results of the remaining ten fluvial sediment samples (Dataset S1). Moreover, the data include the depositional age map of uplifted older foreland sediments across the western Mohand Range (Dataset 2) and the map of best-fit 10^Be concentration inherited from Himalayan paleoerosion (Dataset 3) and sediment burial in the foreland (Dataset 4). We also include a map of the best-fit 10^Be concentration produced during modern erosion of the Mohand Range (Dataset 5) and a map of the best-fit uplift/erosion rates across the western Mohand Range (Dataset 6).
For more information (e.g., sampling method, analytical procedure, and data processing), please refer to the main article (Mandal et al., 2023).
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).