藏南拆离系活动制约分析数据（2018-2022）

喜马拉雅淡色花岗岩广泛分布于北喜马拉雅片麻岩穹隆（NHGD）和大喜马拉雅结晶杂岩体（GHC）顶部，一般受滑脱断层控制。这些前构造、同构造和后构造淡色花岗岩的年龄可用于限制分离结构（如藏南分离系统，STDS）的活动。对喜马拉雅东部STDS活动时间的研究比较稀少。在这项研究中，测量了在中国西藏山南市洛扎、库局、肖战和错那洞四个地区，受STDS和NHGD影响的同构造和后构造淡色花岗岩的锆石和独居石U-Th-Pb年代学。结果表明，受STDS影响的洛扎地区最古老的同构造的二云母花岗岩为24 -25 Ma，因此STDS活动的时间在或略早于25 Ma。最年轻的同构造淡色花岗岩是错那洞含地区石榴石的白云母花岗岩，成岩年龄为 18.4 Ma。最古老的未变形后构造淡色花岗岩（不受 STDS 影响）是肖站白云母花岗岩，其年龄为 17.4 Ma 。因此，STDS活动的结束可以限制在18.4-17.4 Ma。 STDS包括三种形式：NHGD（STDS的北延伸）中的滑脱断层，GHC和特提斯喜马拉雅序列之间的内部STDS，以及同形klippes底部的外部STDS。本文对上述三种滑脱带的活动时限进行了综合总结。基于这项工作，该地区STDS向北延伸（塑性变形）时间被认为是28-17 Ma。 GHC的折返主要受顺序剪切控制。第一，GHC顶部的藏南逆冲断层系统（STDS的前身）在45-28 Ma向南逆冲；然后，GHC 中部的高喜马拉雅断层在 28-17 Ma 形成向南延伸的韧性逆冲断层；最后，GHC底部的主中逆冲断层在17-9 Ma向南逆冲。Himalayan leucogranites are extensively distributed within the North Himalayan Gneiss Domes (NHGD) and at the top of the Greater Himalayan Crystalline Complex (GHC), and their emplacement is generally controlled by detachment faults. The ages of these pre-tectonic, syn-tectonic, and post-tectonic leucogranites can be used to constrain the activity of detachment systems, such as the South Tibetan Detachment System (STDS). Research on the activity timing of the STDS in the eastern Himalaya remains relatively scarce. In this study, we conducted zircon and monazite U-Th-Pb geochronological analyses for syn- and post-tectonic leucogranites affected by the STDS and NHGD in four localities: Luozha, Kuju, Xiaozhan, and Cuonadong, Shannan City, Tibet, China. The results indicate that the oldest syn-tectonic two-mica granite in the STDS-affected Luozha area yields a crystallization age of 24–25 Ma, thus constraining the onset of STDS activity at or slightly earlier than 25 Ma. The youngest syn-tectonic leucogranite is the garnet-bearing muscovite granite from the Cuonadong area, with a crystallization age of 18.4 Ma. The oldest undeformed post-tectonic leucogranite (unaffected by the STDS) is the Xiaozhan muscovite granite, with a crystallization age of 17.4 Ma. Accordingly, the termination of STDS activity can be constrained to the interval of 18.4–17.4 Ma. The STDS comprises three types of structures: detachment faults within the NHGD (the northern extension of the STDS), the internal STDS between the GHC and the Tethyan Himalayan Sequence, and the external STDS at the base of geometrically similar klippes. This paper comprehensively summarizes the activity timeframes of the three aforementioned detachment zones. Based on this study, the activity period of the northern extension of the STDS in this region (accompanied by plastic deformation) is estimated to be 28–17 Ma. The exhumation of the GHC is primarily controlled by sequential shearing. First, the South Tibetan Thrust System (the precursor of the STDS) at the top of the GHC underwent southward thrusting during 45–28 Ma; then, the High Himalaya Thrust in the middle of the GHC formed a southward-dipping ductile thrust fault during 28–17 Ma; finally, the Main Central Thrust at the bottom of the GHC underwent southward thrusting during 17–9 Ma.

搜集汇总

背景与挑战

背景概述

该数据集为藏南拆离系（STDS）活动制约分析数据，基于2018-2022年在喜马拉雅东部四个地区采集的淡色花岗岩锆石和独居石U-Th-Pb年代学测量结果，旨在限制STDS的活动时间。分析表明STDS活动时间在或略早于25 Ma，结束于18.4-17.4 Ma，其向北延伸的塑性变形时间为28-17 Ma，为理解喜马拉雅地区大地构造演化提供了关键年代学约束。数据集以PDF格式存储，大小为16.67 MB，涵盖固体地球科学、地球化学和大地构造等主题。