柴达木盆地北缘30Ma前的快速冷却事件及构造意义——^(40)Ar/^(39)Ar及FT热年代学制约  

Cooling Event around 30 Ma in the Northern Edge of the Qaidam Basin:Constraints from ^(40)Ar/^(39)Ar and Fission Track Thermochronology

作　　者：王非[1] 罗清华[2] 李齐[1] 万景林[1] 郑德文[1] 李大明[1] 王瑜[1] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]台湾大学地质学系

出　　处：《地质论评》2002年第S1期88-96,共9页Geological Review

基　　金："973"项目"青藏高原形成演化及其环境;资源效应"资助成果

摘　　要：对柴达木北缘两个花岗质岩体的钾长石和磷灰石分别进行了氩多重扩散域理论(MDD)模拟及裂变径迹年龄测定,得到了这些岩体的冷却历史。该冷却历史表明,30 Ma左右这里曾发生过一次快速冷却事件(7.5～9.4℃/Ma),并伴随着去顶剥蚀作用,这可能和该地区的抬升活动有关,造成地壳厚度在这一时期增加。这可能和阿尔金断裂的走滑活动有关。An ^(40)Ar/^(39)Ar thermochronological study was carried out on two suites of granitoid collected along the northern margin of the Qaidam basin to better constrain the mechanism accommodating the India-Asia collision around the Qaidam basin (northern Tibet), which is essential to understanding the evolution of the entire deformation area. Biotite and K-feldspar were analyzed and the cooling histories of the latter were modeled. The cooling histories based upon K-feldspar modeling showed that samples recorded simultaneously an important cooling event (7～10℃/Ma) round 30 Ma, which was thought to reflect an increasing rate of denudation related to the tectonic activity in this area associated with uplift, suggesting that it experienced an important crustal thickening period 30 Ma ago. This crustal thickening event was suggested to be related to the great Asian strike-slip faults in a way, which remains problematic but possibly associated to the Cenozoic propagation of the Altun fault.

关 键 词：快速冷却事件 多重扩散域模式(MDD) 去顶作用 阿尔金断裂 

分 类 号：P597.3[天文地球—地球化学]