Tectonometamorphic discontinuities in the Greater Himalayan Sequence: a local or a regional feature?
Tectonometamorphic discontinuities in the Greater Himalayan Sequence: a local or a regional feature?
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DOI：
10.1144/sp412.3
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发表时间：
2015-09
期刊：
影响因子：
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通讯作者：
C. Montomoli;R. Carosi;S. Iaccarino
中科院分区：
文献类型：
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作者：
C. Montomoli;R. Carosi;S. Iaccarino
大喜马拉雅层序（GHS）是喜马拉雅地区的主要构造单元之一，沿走向延伸2400多km。它被认为是一个由藏南拆离构造（STD）和主中央逆冲断层（MCT）所约束的连贯构造单元。然而，在它内部的逆冲断层已经在几个地方被确认，并且主要被解释为在MCT激活后水晶单位的主要剥露阶段之后活跃的无序逆冲断层。最近的综合研究允许几个韧性剪切带的GHS的核心，顶部到西南方向的剪切（高喜马拉雅不连续性（HHD））的识别。独居石U-Th-Pb原位年龄比MCT年龄大。压力和温度演化数据证明，这些剪切带影响了该带的构造变质演化，并记录了不同的压力和温度条件下，在上盘和下盘的HHD。WNW-ESE向HHD与全球统一制度中确认的其他不连续性的相关性导致了这样的建议，即它是一个长达数百公里的构造特征，在区域尺度上将全球统一制度分为两个不同的部分。
Abstract The Greater Himalayan Sequence (GHS) is one of the major tectonic units of the Himalaya running for more than 2400 km along-strike. It has been considered as a coherent tectonic unit bound by the South Tibetan Detachment (STD) and the Main Central Thrust (MCT). However, thrusts within it have been recognized in several places and have been mainly interpreted as out-of-sequence thrusts being active after the main phase of exhumation of the crystalline unit after the MCT activated. Recent integrated studies allow the recognition of several ductile shear zones in the core of the GHS, with top-to-the-SW-sense of shear (Higher Himalayan Discontinuity (HHD)). U–Th–Pb in situ monazite ages provide ages older than the MCT. Data on pressure and temperature evolution testify that these shear zones affected the tectonometamorphic evolution of the belt and different pressure and temperature conditions were recorded in the hanging wall and footwall of the HHD. The correlation of the WNW–ESE-trending HHD with other discontinuities recognized in the GHS led to the proposal that it is a tectonic feature running for several hundred kilometres, documented at the regional scale dividing the GHS in two different portions.