Timing of Displacement along the Yardoi Detachment Fault, Southern Tibet: Insights from Zircon U-Pb and Mica ~(40)Ar-~(39)Ar Geochronology
Timing of Displacement along the Yardoi Detachment Fault, Southern Tibet: Insights from Zircon U-Pb and Mica ~(40)Ar-~(39)Ar Geochronology
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藏南 Yardoi 拆离断层沿线位移的时限：锆石 U-Pb 和云母 ~(40)Ar-~(39)Ar 地质年代学的见解
DOI：
10.1007/s12583-019-1223-z
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发表时间：
2019
影响因子：
3.3
通讯作者：
Ma Zeliang
中科院分区：
文献类型：
--
作者：
Dong Hanwen;Meng Yuanku;Xu Zhiqin;Cao Hui;Yi Zhiyu;Ma Zeliang
Yardoi圆顶位于西北-东南延伸的北喜马拉雅圆顶（NHD）的东端。穹隆出露了核部的花岗岩岩体和被上拆离断层和下拆离断层分隔的三个岩性构造单元。Yardoi拆离断层（YDF），对应于较低的拆离断层，是一个800米的强烈变形的顶NW向剪切带。LA-ICP-MS锆石U-Pb定年结果表明，白云岩墙群的结晶年龄为19.57±0.23 ~ 15.5± 0.11Ma，表明白云岩墙群的韧性运动沿着YDF开始于约100 Ma。20马。白云母的~（40）Ar/~（39）Ar年龄为14.05±0.2 ~ 13.2±0.2 Ma，黑云母的~（40）Ar/~（39）Ar年龄为13.15±0.2 Ma，表明折返作用导致了冷却，从白云母中~14 Ma的370 ºC Ar封闭温度到黑云母中~13 Ma的335 ºC Ar封闭温度。雅尔多穹隆和特提斯喜马拉雅序列中其他穹隆的新年代学资料表明，该地区深部构造层面的韧性变形开始于~36 Ma或之前，导致中地壳构造层面的向南韧性流动持续20 ~ 13 Ma。与NHD中的其他圆顶相比，Yardoi圆顶的冷却年龄显示出明显的历时性，并且从西喜马拉雅到东喜马拉雅逐渐年轻。
The Yardoi dome is located in the eastern end of the northwest-southeast extending North Himalayan domes(NHD). The dome exposes a granite pluton in the core and three lithologictectonic units separated by the upper detachment fault and the lower detachment fault. The Yardoi detachment fault(YDF), corresponding to the lower detachment fault, is a 800 m strongly deformed top-NW shear zone. LA-ICP-MS zircon U-Pb dating yielded a crystallization ages of 19.57±0.23 to 15.5±0.11 Ma for the leucogranite dyke swarm, which indicates that the ductile motion along the YDF began at ca. 20 Ma. The ~(40)Ar/~(39)Ar muscovite ages of 14.05±0.2 to 13.2±0.2 Ma and the ~(40)Ar/~(39)Ar biotite age of 13.15±0.2 Ma, suggest that the exhumation led to cooling through the 370 ºC Ar closure temperature in muscovite at ~14 Ma to the 335 ºC Ar closure temperature in biotite at ~13 Ma. Our new geochronological data from the Yardoi dome and other domes in the Tethyan Himalayan Sequences suggest that the ductile deformation in the region began at or before ~36 Ma in a deep tectonic level, resulting in southward ductile flow at the mid-crustal tectonic level that continued from 20 to 13 Ma. Comparing the Yardoi dome to other domes in the NHD, the cooling ages show a clear diachronism and they are progressively younger from the West Himalayan to the East Himalayan.