Assessing the activity of Eastern Himalayan extensional structures: evidence from low-temperature thermochronology of granitic rocks from Yadong

Xu, T., Li, Y., Stuart, F. M. , Ma, Z., Bi, W., Jia, Y. and Yang, B. (2024) Assessing the activity of Eastern Himalayan extensional structures: evidence from low-temperature thermochronology of granitic rocks from Yadong. Minerals, 14(1), 66. (doi: 10.3390/min14010066)

Abstract

The east–west-trending South Tibetan Detachment System (STDS) and north–south-trending rifts (NSTRs) are the two main types of extensional structures that have developed within the Tibetan Plateau during continent–continent collision since the early Cenozoic. They have played significant roles in the evolution of the plateau, but it is unclear how they are related genetically. In the Yadong area of the eastern Himalaya, the NSTRs cross-cut the STDS. Apatite and zircon fission track ages of a leucogranite pluton in the footwall of the two extensional faults can be used to reconstruct the cooling and exhumation history and thereby constrain the activity of extensional structures. The new AFT ages range from 10.96 ± 0.70 to 5.68 ± 0.37 Ma, and the ZFT age is 13.57 ± 0.61 Ma. Track length distributions are unimodal, albeit negatively skewed, with standard deviations between 1.4 and 2.1 µm and mean track lengths between 11.6 and 13.4 µm. In conjunction with previously published datasets, the thermal history of the region is best explained by three distinct pulses of exhumation in the last 16 Ma. The first pulse (16–12 Ma) records a brittle slip on the STDS. The two subsequent pulses are attributed to the movement on the Yadong normal fault. The normal fault initiated at ~12 Ma and experienced a pulse of accelerated exhumation between 6.2 and 4.7 Ma, probably reflecting the occurrence of two distinct phases of fault activity within the NSTRs, which were primarily instigated by slab tear of the subducting Indian plate.

• Item Type: Articles
• Additional Information: : This work was supported by the National Natural Science Foundation of China (Grant No. 91955206), the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (Grant No. 2019QZKK0803), the China Geological Survey (Grant No. DD20190057), the Fundamental Research Funds for the Central Universities (Grant No. 35732020071), and the National Natural Science Foundation of China (Grant No. 42302241).
• Keywords: Southern Tibet, low-temperature thermochronology, Pecube, extensional structure, exhumation, Yadong region.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: XU, Tiankun and Stuart, Professor Fin
• Authors: Xu, T., Li, Y., Stuart, F. M., Ma, Z., Bi, W., Jia, Y., and Yang, B.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Minerals
• Publisher: MDPI
• ISSN: 2075-163X
• ISSN (Online): 2075-163X
• Copyright Holders: Copyright © 2024 by the authors.
• First Published: First published in Minerals 14(1): 66
• Publisher Policy: Reproduced under a Creative Commons licence