新疆塔什库尔干温泉地区花岗岩体侵入与新生代构造变形:对东北帕米尔中新世构造演化的启示

帕米尔高原是受到印度-亚洲大陆碰撞、持续汇聚影响最显著的地区之一，以强烈地壳增厚和缩短、大量断裂和片麻岩穹窿的形成以及广泛的陆内岩浆活动为特征。以往有关帕米尔陆内岩浆岩的讨论多集中于对其地球化学成分及其所指示的构造背景的研究方面，而对岩浆形成与大型新生代构造之间的联系研究较少。本文通过对东北帕米尔塔什库尔干温泉地区新生代花岗岩及其围岩中锆石U-Pb和Ar-Ar年代学研究，结合该地区新生代构造变形分析，揭示岩浆侵入与区域构造变形之间的关系。U-Pb及Ar-Ar测年结果显示温泉地区花岗岩脉形成时代为中新世（11.8±0.2Ma），其及其围岩在10.8±0.1Ma冷却到300℃左右；中新世花岗岩脉中继承锆石及围岩片岩中碎屑锆石U-Pb的年龄分布特征迥异，它们分别具有类似松潘-甘孜地体以及中帕米尔地体的物质来源。花岗岩内部几乎无变形，围岩片岩变形主要体现为近E-W向的伸展构造，反映其形成于拉张为主的构造应力环境。结合区域构造背景，推测温泉中新世花岗岩脉为公格尔山、慕士塔格峰构造单元岩石部分熔融产物，是在东北帕米尔地壳从挤压增厚向局部伸展转换的过程中形成的，此时，公格尔伸展断裂系可能已经开始发育；此后，直到6~4Ma，公格尔伸展断裂系开始快速运动，与之相伴公格尔-慕士塔格片麻岩穹窿快速折返。

Emplacement of granitic pluton and Cenozoic deformation in the Wenquan region, Tashkorgan, Xinjiang: The implications for the Miocene tectonic evolution of the Northeast Pamir

The Pamir Plateau is one of the most important regions to study effects of the India-Asia continental collision and its continuous convergence. It is characterized by significantly crust thickening and shortening, formation of lots of faults and the gneiss domes as well as volumerous intra-continental magmatism. The previous works on the intra-continental magmatic rocks in Pamir area focused on their geochemical compositions and indicative tectonic settings, but few studies on the relationship between the formation of the magmatism and the regional deformation. This paper presents new structural geology, U-Pb and Ar-Ar chronological data in the Wenquan area, Tashkorgan, Northeast Pamir, reveals the relationship between the emplacement of granitic pluton and the regional deformation. The U-Pb dating results showed that the granitic veins in the Wenquan area were formed at 11.8±0.2Ma. They and their wall rocks cooled to Ar-Ar closure temperature at 10.8±0.1Ma. The inherited zircons in Miocene granitic veins and detrital zircons in wall rocks display quite different U-Pb age characteristics. They were most likely derived from the Songpan-Ganzi and Central Pamir terrains, respectively. The granites show a non-deformed feature. The surrounding schists are manifested as the E-W striking extensional structures, reflecting an extensional stress field. Combined with regional tectonic settings, it indicates that the Miocene granitic veins in the Wenquan region are the partial melting products from the structural terrane of Konger Shan and Muztaghata. The granites were formed during the transformation stage from the crustal thickening to local crustal extension in the Northeast Pamir. It is also possible that the Konger extensional fault system was activated during this process. Until 6~4Ma, rapid slipping along the Kongershan extensional fault system and exhumation of the Konger-Muztaghata gneiss dome commenced.