藏南日喀则盆地西部地区及其邻区新生代以来的隆升剥露历史 来自碎屑岩磷灰石裂变径迹的约束

马泽良; 李广伟; 许志琴; 郑艺龙

doi:10.12097/gbc.2023.01.017

藏南日喀则盆地西部地区及其邻区新生代以来的隆升剥露历史来自碎屑岩磷灰石裂变径迹的约束

Cenozoic exhumation history of the western part of Xigaze basin and its adjacent area, South Xizang: Constraints from the fission track of clastic apatite

摘要

摘要:
研究目的 西藏日喀则盆地记录了新特提斯洋俯冲和随后印度-亚洲大陆碰撞的重要信息，对日喀则盆地的研究有助于进一步理解印度-亚洲的碰撞过程。
研究方法 利用磷灰石裂变径迹对藏南日喀则盆地西部地区及其邻区隆升剥露过程进行研究。
研究结果 结果显示，日喀则盆地西部地区在30±5 Ma左右时埋藏深度达到最大，在30~23 Ma期间遭受快速剥蚀，随后缓慢冷却直至出露地表。结合区域低温热年代学研究，该盆地沿东西走向的剥露过程存在差异，东部开始遭受剥蚀的时间较早，西部较晚。
结论盆地东西开始遭受剥蚀的差异可能受控于印度-亚洲大陆碰撞过程中印度板片向北俯冲角度的影响，东部俯冲角度较陡，西部较缓，这与通过地球物理研究得到的现今印度大陆的俯冲角度东西变化规律基本一致。

Abstract:
Objective The significant information of the convergence of India and Asia plates has been recorded in the Xigaze basin and its adjacent area within the India−Asia collision zone.
Methods We present new apatite fission track in the western part of the Xigaze basin and its adjacent area to elucidate the burial and exhumation history of the region.
Results The data and inverse thermal history modelling show that the western part of basin reached its maximum palaeotemperature at ca. 30±5 Ma, followed by rapid cooling between 30 Ma and 23 Ma, and then commenced cooling slowly until present day. Combined with previous studies, the initial cooling time varies along the strike of the basin.
Conclusions The onset of cooling in the eastern part of the basin is older than the western part. This difference is probably controlled by the lateral variable subduction angles of the Indian lithospheric slab, which is revealed by the seismic tomography.

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