标题：Timing of Displacement along the Yardoi Detachment Fault, Southern Tibet: Insights from Zircon U-Pb and Mica Ar-40-Ar-39 Geochronology
作者：Dong, Hanwen; Meng, Yuanku; Xu, Zhiqin; Cao, Hui; Yi, Zhiyu; Ma, Zeliang
作者机构：[Dong, Hanwen; Cao, Hui; Yi, Zhiyu; Ma, Zeliang] Chinese Acad Geol Sci, Inst Geol, Minist Nat Resources, Key Lab Deep Earth Dynam, Beijing 100037, Peo 更多
会议名称：4th IGCP-649 Diamonds and Recycled Mantle Workshop
来源：JOURNAL OF EARTH SCIENCE
关键词：leucogranite; geochronology; Yardoi dome; southern Tibet; Himalayan; Orogen
摘要：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 Ar-40/Ar-39 muscovite ages of 14.05 +/- 0.2 to 13.2 +/- 0.2 Ma and the Ar-40/Ar-39 biotite age of 13.15 +/- 0.2 Ma, suggest that the exhumation led to cooling through the 370 degrees C Ar closure temperature in muscovite at approximate to 14 Ma to the 335 degrees C Ar closure temperature in biotite at approximate to 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 approximate to 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.