The exhumation and uplift of the southern Shigu complex since Early Cretaceous evidenced by zircon and apatite fission track
The exhumation and uplift of the southern Shigu complex since Early Cretaceous evidenced by zircon and apatite fission track
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发表时间：
2016
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通讯作者：
C. Xiaoyu;Liu Junlai;Wu Wenbin
中科院分区：
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作者：
C. Xiaoyu;Liu Junlai;Wu Wenbin
石鼓杂岩体位于青藏高原东南缘，主要分布在石鼓和中地安地区。该杂岩体经历了变质作用和变形作用的多期叠加。为了揭示杂岩体浅部地壳层面的低温热演化和折返历史，正确认识藏东变质穹窿的折返和构造演化过程，沿石鼓镇—拉巴支剖面采集了锆石和磷灰石裂变径迹样品，进行了裂变径迹分析。分析结果表明，石鼓杂岩从早白垩世（133~145Ma）到渐新世（31Ma）首先经历了缓慢的冷却折返过程，自渐新世开始经历了较快的冷却过程。通过磷灰石裂变径迹反演模拟的时间-温度历史也反映了第二阶段相对快速的冷却过程。从区域构造分析来看，拉萨板块与羌塘板块碰撞的远场效应可能对杂岩体早白垩世折返产生了强烈影响。此外，印度-欧亚大陆碰撞和碰撞后效应对杂岩体的新生代折返产生了深远的影响。
The Shigu complex lies on the southeastern margin of the Tibetan Plateau, and is mainly distributed in Shigu and Zhongdi?an areas. The complex has experienced polyphase superposition of metamorphism and deformation. In order to reveal the low tem?perature thermal evolution and exhumation history at the shallow crustal level of the complex and correctly understand the exhuma?tion and tectonic evolution of the metamorphic dome in eastern Tibet, the authors collected zircon and apatite fission track samples for the fission track analysis along the Shigu Town-Labazhi section. The analytical results show that the Shigu complex firstly experi?enced a slow cooling and exhumation from Early Cretaceous (133~145Ma) to Oligocene (31Ma), and a relatively rapid cooling pro?cess started from Oligocene. Time-temperature history simulated by inverse modeling of apatite fission track also reflects a relatively rapid cooling process at the second stage. From regional structural analysis, it is suggested that the far-field effects of the collision be?tween the Lhasa and Qiangtang plates may have strongly affected the Early Cretaceous exhumation of the complex. Furthermore, the Indian-Eurasian collision and post-collisional effects had profound effects on the Cenozoic exhumation of the complex.