新生代阿尔金山脉隆升历史的裂变径迹证据

Fission Track Dating of Apatite Constrains on the Cenozoic Uplift of the Altyn Tagh Mountain

10个片麻岩和花岗岩的磷灰石裂变径迹年龄值位于 3 5 .6～ 13 .6Ma之间 ,表明了阿尔金山脉的隆升开始于渐新世 ,并一直延续至中新世。山脉早期的隆升速率较低 ,后期可能存在一个快速的隆升时期 ;阿尔金山脉并非整体的均匀隆升 ,其内分布的NEE走向的断裂也局部控制了山体的隆升 ;如果山脉的隆升是阿尔金断裂左行走滑的结果 ,那么可推测阿尔金断裂大型左行走滑的起始时间应为渐新世。区域资料分析表明 ,青藏高原北缘在渐新世至中新世期间发生了大规模的、区域性的抬升。

samples of gneiss and granite from the Altyn Tagh Mountain are dated by fission track of apatite. The result yields ages from 35.6 Ma to 13.6 Ma, which suggests that the uplift of the Altyn Tagh mountain began from Oligocene and lasted till Miocene. During the early stage, the uplift rate was very low, and probably a quick uplift occurred later, which is supported by regional geology, structure evolution and sedimentary sequences. The result indicates that the local uplift of the mountain was also controlled by some NEE-trending faults within the mountain. As the uplift of the mountain was probably only related to the strike-slip of the Altyn Tagh fault, the authors hold that the initial age of the left-lateral strike-slip of the fault should have been Oligocene. Regional data also show that a large-scale regional uplift of mountains in the northern edge of the Qinghai-Tibetan plateau occurred during Oligocene-Miocene period.