The South Tibetan Detachment System is an important extensional fault zone, separating the Greater Himalayan Sequence from the overlying Tethyan Himalayan Sequence, and is well exposed in the upper reaches of the Dhauliganga valley, NW Himalaya. This fault system is characterized by the occurrence of an extensive Cambro–Ordovician granite belt between Sutlej and Dhauliganga valleys, although only a few small granitoids intrude the high-grade mylonite gneiss of the Greater Himalayan Sequence in its immediate footwall. These bodies yielded U-Pb zircon crystallization ages between 498.92 ± 5.5 Ma and 486.54 ± 2.3 Ma. This work postulates that the South Tibetan Detachment System evolved as a major proto-tectonic marginal extensional terrane boundary during the Cambro–Ordovician Kurgiakh/Bhimphedian Orogeny, when it was the conduit for emplacement of the Cambro–Ordovician granite belt. Denudation of the Neoproterozoic Greater Himalayan Sequence and the Paleozoic granites on its footwall provided approximately ∼ 10 km thick sediments into the Tethyan Basin due to this fault system as a master growth fault. Reactivation of this fault system controlled further melting and emplacement of the Higher Himalayan Leucogranite belt during the Cenozoic. Zircon growth is observed in two distinct modes: pulsative from the Late Eocene to Early Oligocene, with peaks at 33.99 ± 1.07 Ma, 30.53 ± 0.32 Ma and 25.03 ± 0.54 Ma; and in the continuous mode from 23.68 ± 0.94 Ma to 13.30 ± 0.30 Ma, in the Miocene, for nearly 10.0 myr. These datasets reveal some of the oldest pulsative movements in the Late Eocene–Early Oligocene during crustal thickening, thrusting and associated metamorphism, followed by continuous extension during the Miocene. Data from the South Tibetan Detachment System are distinct in character, and do not support either its eastwards younging or diachronous movements along the Dhauliganga valley.

中文翻译：

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南藏分离系统 （STDS），喜马拉雅山西北部：可能的寒武纪-奥陶纪构造地层边界及其新生代重新动员


南藏分离系统是一个重要的伸展断层带，将大喜马拉雅层序与上覆的特提斯喜马拉雅层序分开，在喜马拉雅山西北部的 Dhauliganga 山谷的上游暴露良好。该断层系统的特点是在 Sutlej 和 Dhauliganga 山谷之间出现了广泛的寒武纪-奥陶纪花岗岩带，尽管只有少数小花岗岩侵入了大喜马拉雅层序在其紧邻下盘的高品位糜棱岩片麻岩。这些体产生的 U-Pb 锆石结晶年龄在 498.92 ± 5.5 马 和 486.54 ± 2.3 马之间。这项工作假设藏南分离系统在寒武纪-奥陶纪 Kurgiakh/Bhimphedian 造山运动期间演变为主要的原始构造边缘伸展地层边界，当时它是寒武纪-奥陶纪花岗岩带的放置管道。新元古代大喜马拉雅层序的剥蚀和其下盘的古生代花岗岩为特提斯盆地提供了大约 ∼ 10 公里厚的沉积物，因为该断层系统是主要生长断层。这个断层系统的重新激活控制了新生代高喜马拉雅白花岗岩带的进一步熔融和放置。锆石生长以两种不同的模式观察到：从始新世晚期到渐新世早期的脉动生长，峰值在 33.99 ± 1.07 马、30.53 ± 0.32 马和 25.03 ± 0.54 马;在中新世，从 23.68 ± 0.94 马 到 13.30 ± 0.30 马的连续模式下，接近 10.0 MYR。这些数据集揭示了晚始新世至早渐新世在地壳增厚、逆冲和相关的变质作用期间一些最古老的脉动运动，随后在中新世期间持续延伸。 来自藏人南部分离系统的数据具有鲜明的特征，不支持其沿 Dhauliganga 山谷向东的年轻或历时运动。