西昆仑山奇台达坂花岗岩锆石TIMSU-Pb测年及热演化历史分析  

Zircon TIMS U-Pb dating of the Qitaidaban granite in the West Kunlun Mountains and its thermal evolution history

作　　者：黎敦朋[1] 赵越[1] 胡健民[1] 李新林 周小康 王向利 杜少喜 肖爱芳 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]陕西省地质调查院,陕西西安710016

出　　处：《中国地质》2007年第6期1013-1021,共9页Geology in China

基　　金：中国地质调查局地质大调查项目(1212010610108和200313000003)资助。

摘　　要：应用锆石TIMSU-Pb测年获得西昆仑山奇台达坂花岗岩年龄为(202.2士3.4)Ma(MSWD=8.65);利用不同海拔高度获得磷灰石裂变径迹测定年龄为24.8～14.0Ma。通过裂变径迹热史模拟,并结合前人40Ar-39Ar测年数据,得出西昆仑山奇台达坂花岗岩就位以来,至少经历了三快二慢的冷却降温(隆升剥蚀)过程:即202.2～195.6Ma、26～15Ma和5Ma以来3个阶段的快速降温(隆升剥蚀),195.6～26Ma和15～5Ma2个阶段的缓慢冷却降温(隆升剥蚀)。西昆仑山地壳最上部约3km的快速去顶作用主要发生于26～15Ma和5Ma以来,它是印度板块向欧亚板块碰撞的结果。TIMS U-Pb dating of zircons from the Qitaidaban granite in the West Kunlun Mountains yielded an age of 202.2＋3.4 Ma （MSWD=8.65）, and the apatite fission-track dating of samples taken at different altitudes yielded ages of 24.8-14.0 Ma. Fission-track thermal history modeling, combined with the previous data of ^40Ar-^39Ar dating, shows that the Qitaidaban granite underwent three rapid cooling stages （uplift and erosion） and two slow cooling stage （uplift and erosion） at least, i.e.： rapid cooling at 202.2-195.4 Ma, 26-15 Ma and since 5 Ma, and slow cooling at 195.4-26 Ma and 26-15 Ma. The rapid deroofing of the -3 m thick topmost part of the crust below the West Kunlun Mountains took place at 26-15 Ma and since 5 Ma, which was the result of Eurasia-India collision.

关 键 词：锆石TIMS U—Pb测年 裂变径迹 热演化历史 西昆仑山 

分 类 号：P588.121[天文地球—岩石学]