Neogene Chemical Weathering and Provenance Records of the Western Himalaya Preserved in the Arabian Sea

Abstract

Some tectonic models for the Himalaya emphasize the importance of surface processes in controlling the structural evolution. To investigate this tectonic–climatic interactions, and the weathering and erosion of the western Himalaya, International Ocean Discovery Program (IODP) Expedition 355 drilled two sites (site U1456 and U1457) in Laxmi Basin, which located in the Eastern Arabian Sea. In my research project, I plan to use a series of geochemical and geochronological methods on the sediment samples from the cores of these two sites, and sediments from an industrial borehole Indus Marine A-1, which near the Indus river mouth, to reconstruct a climatic and provenance record of Western Himalaya since Neogene. According to the U-Pb geochronology analysis on the detrital zircon grains from the coarse marine sediments recovered from these two IODP sites and coupled with the Sr and Nd isotopic study prove the sediments recovered in site U1456 and U1457 are mainly derived from Indus river, rather than from Indian peninsula. Also, this could allow us to reconstruct the erosion patterns potentially change through time in the region of Western Himalayan area. Furthermore, we use the apatite fission track (AFT) analysis on these same samples, to constrain the exhumation rates in the western Himalaya and Karakoram since middle Miocene. Lastly, to further understand the long-term climate variation, we study the chemical weathering evolution, by using the Clay minerals, bulk sediment geochemistry, Diffuse Reflectance Spectroscopy (DRS), and magnetic susceptibility, to constrain the degrees of chemical alteration and the long-term climate change since Miocene