阿尔金山东段地质热年代学与构造演化

文中综合分析了青藏高原北缘阿尔金山东段地质热年代学和构造体系演化。阿尔金山东段从太古宙陆核发育而来,经历了元古宙稳定地台和新元古代大陆裂解阶段,形成了早古生代阿尔金洋和沟 弧 盆构造体系,发育了奥陶纪早期的板块俯冲、碰撞造山作用和奥陶纪-志留纪之交的岛弧岩浆活动(峰期年龄为443 Ma)。石炭纪洋盆闭合之后,该地区进入陆内构造发育阶段。其中,占主导地位的是以拉配泉断裂为代表的中生代伸展构造和新生代阿尔金断裂系的左行走滑断裂活动,它们分别控制了中生代两期热冷却事件和新生代地块快速抬升 冷却事件。地质热年代学年龄数据为阿尔金山东段不同时期形成的不同地块勾画了不同的热冷却历史,由此可区分不同时期不同构造事件对区域热冷却历史的影响。

Geothermochronology and tectonic evolution of Eastern Altyn Tagh Mountains,Northwestern China

Abstract: This paper gives the integrated analyses of geothermochronology and tectonic system evolution of eastern Altyn Tagh Mountains, northern Qinghai Tibet Plateau. The eastern Altyn Tagh is considered to have developed from Archean continental core, through Proterozoic stable platform and continental rifting in the Neo Proterozoic, to “Altyn Ocean” and trench arc basin system in the Early Paleozoic plate subduction, collisional orogeny and arc magmatism (with a peak activity at 443 Ma) occurred through the Ordovician and the Early Silurian. After the closing of “Altyn Ocean” in the Carboniferous, the eastern Altyn Tagh entered into the stage of continental tectonic development, and had undergone two major tectonic events since then, which are Mesozoic extension appeared as Lapeiquan detachment faulting and Cenozoic strike slip faulting on Altyn Tagh Fault. The regional thermal cooling history of the eastern Altyn Tagh was controlled by these tectonic events and the tectonic events developed there were recorded by the thermal cooling history. Various massifs developed in different time had experienced different cooling histories which are well depicted by the geothermochronologic data. Therefore, geothermochronology is a helpful method for understanding the regional tectonic evolution of eastern Altyn Tagh area.