Erosional Unroofing of the Nepal Himalayas Over the Past 12Ma: 87Sr/86Sr and Sedimentary Petrological Indicators from Siwalik Foreland Deposits

小行星9418207 来自喜马拉雅山脉隆起的沉积物的风化对海洋化学、区域（现在的季风）气候以及可能对大气pCO 2产生了重大影响。 反映喜马拉雅隆升影响的最清晰的指标之一是海洋87 Sr/86 Sr记录。 然而，海洋锶记录和构造作用和风化率在喜马拉雅腹地之间的具体联系几乎没有记录。 喜玛拉雅山脉的中新世-更新世碎屑侵蚀记录包含在喜玛拉雅山脉前缘山脉和孟加拉海底扇中出露的西瓦利克组前陆盆地沉积物中。 本研究将探讨在过去的12马沉积在尼泊尔中部和西部的西瓦利克沉积物中的沉积物，风化产物和水生（河流）贝壳的87 Sr/86 Sr比的变化。 这些同位素组成将与喜马拉雅山的特定构造和侵蚀事件相关，提供造山带物理过程之间的直接联系（例如，个别逆冲位移事件）以及沉积物和水成分的变化。 反过来，这些研究将允许87 Sr/86 Sr比值的变化和其他方面的西瓦利克沉积物的海洋和孟加拉海底扇沉积物的同位素演化进行比较。

9418207 Quade Weathering of sediments derived from uplift of the Himalayas has had a major impact on the chemistry of the oceans, on regional (now monsoonal) climate, and probably on atmospheric pCO2. One of the clearest proxies of the effects of Himalayan uplift is the marine 87Sr/86Sr record. However, the specific links between the marine Sr record and tectonism and weathering rates in the Himalayan hinterland are virtually undocumented. The Miocene-Pleistocene detrital record of erosion of the Himalayas is contained in the Siwalik Group foreland-basin sediments exposed in the Himalayan frontal ranges, and in the Bengal submarine fan. This research will examine changes in the 87Sr/86Sr ratio of sediment, weathering products, and aquatic (riverine) shells in Siwalik sediments deposited in central and western Nepal over the past 12 Ma. These isotopic compositions will be correlated with specific tectonic and erosional events in the Himalayas, providing a direct link between physical processes in the orogenic belt (e.g., individual thrust-displacement events) and changes in sediment and water composition. In turn, these studies will permit comparison of changes in 87Sr/86Sr ratios and other aspects of Siwalik sediments to the isotopic evolution of the ocean and Bengal submarine fan sediments.