Provenance of Thal Desert sand: Focused erosion in the western Himalayan syntaxis and foreland-basin deposition driven by latest Quaternary climate change
Provenance of Thal Desert sand: Focused erosion in the western Himalayan syntaxis and foreland-basin deposition driven by latest Quaternary climate change
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DOI：
10.1016/j.earscirev.2020.103220
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发表时间：
2020-08
影响因子：
12.1
通讯作者：
E. Garzanti;W. Liang;S. Andó;P. Clift;A. Resentini;P. Vermeesch;G. Vezzoli
中科院分区：
文献类型：
--
作者：
E. Garzanti;W. Liang;S. Andó;P. Clift;A. Resentini;P. Vermeesch;G. Vezzoli
作为喜马拉雅前陆盆地入口处最新世的印度河沙库，巴基斯坦北部的塔尔沙丘场储存了重要的信息，可用于重建喜马拉雅-喀喇昆仑造山带的侵蚀演化以及末次盛冰期和全新世早期之间发生的前陆盆地景观的变化。这项针对塔尔沙漠沙子的综合来源研究将先前存在的岩相学、重矿物、矿物化学、同位素和地质年代学数据库与原始的大量沉积物地球化学、锆石年龄和 Nd 同位素数据相结合。沙丘砂石英含量低，富含长石、火山岩、变火山岩和变碱岩颗粒，含有非常丰富的透明重矿物组，包括晚白垩世至古近纪早期的超强石和普通锆石颗粒，其特点是镁、钪、钒、钴、镍、铜浓度高，εNd值高达-3.5。总之，这些数据表明，约 40% 的塔尔沙丘沙子是由科希斯坦弧的侵蚀提供的，这一比例远远超过了对现代印度河上游沙子的评估。科希斯坦弧提供的更多碎屑表明了沉积物生成的显着不同条件，在此期间，干旱低地印度河上游的沉积物输送能力降低，大量沙子被风广泛改造并积聚在前陆盆地的沙丘场中。全新世早期，南亚季风重新增强，水和沉积物排放量显着增加，导致塔尔和塔尔沙丘地区被印度河及其旁遮普支流切割，直接受到强季风降雨的影响。
As a latest Pleistocene repository of Indus River sand at the entry point to the Himalayan foreland basin, the Thal dune field in northern Pakistan stores crucial information that can be used to reconstruct the erosional evolution of the Himalayan-Karakorum orogen and the changes in the foreland-basin landscape that took place between the Last Glacial Maximum and the early Holocene. This comprehensive provenance study of Thal Desert sand integrates previously existing petrographic, heavy-mineral, mineral-chemical, isotopic, and geochronological databases with original bulk-sediment geochemistry, zircon-age, and Nd-isotope data. Dune sand is low in quartz and rich in feldspars, volcanic, metavolcanic and metabasite grains, contains a very rich transparent heavy-mineral suite including hypersthene and common zircon grains dated as Late Cretaceous to early Paleogene, and is characterized by high Mg, Sc, V, Co, Ni, Cu concentrations and by εNdvalues as high as −3.5. Together, these data indicate that ~40% of Thal dune sand was supplied by erosion of the Kohistan arc, a proportion that far exceeds the one assessed for modern Upper Indus sand. Greater detrital supply from the Kohistan arc indicates notably different conditions of sediment generation, during a period in which the sediment-transport capacity of the Upper Indus in the dry lowlands was reduced and volumes of sand were extensively reworked by wind and accumulated in dune fields across the foreland basin. In the early Holocene, the renewed strength of the South Asian monsoon and consequently markedly increased water and sediment discharge led to incision of the Thal and Thar dune fields by the Indus River and its Punjab tributaries draining the Himalayan front directly hit by heavy monsoonal rains.