西天山晚古生代以来的抬升-剥露过程:来自多种热年代学方法的约束

Meso-Cenozoic exhumation and uplift history of west Tianshan have been investigated many aspects, such as tectonics, sedimentology and apatite fission track thermochronology. But when and how the India-Eurasia collision affects the exhumation of intracontinental West Tianshan is not well constraints. Differences and stages of exhumation and uplift among many tectonic unit in the Tianshan Orogen are not well documented either. In this project, we will investigate the different tectonic unit from the West Tianshan, by utilizing multiple thermochronometers (zircon U/Pb,40Ar-39Ar、Fission Track, (U-Th)/He dating) to reveal the timing, temperature, spatial location of exhumation on the West Tianshan since the late Palaeozoic; The results could elucidate the Meso-Cenozoic differential exhumation and thermal history in the Tianshan Orogen, and help to understand the Meso-Cenozoic tectonic evolution and driving mechanism. The study could, coupled with available low-temperature thermochronometric data in the northern margin of Tibet Plateau and Tarim basin, further disclose tempo-patial evolution of intracontinental mountain building of West Tianshan due to the far-field effects of the india-Eurasia collision. It could also play an important role to deeply understanding the Meso-Cenozoic tectonic deformation and mechanism in the Central Asian Orogenic Belt.

西天山造山带中-新生代的隆升-剥露历史已经从构造地质学，沉积学以及裂变径迹热年代学等方面做了诸多研究，但对新生代印度-欧亚大陆板块碰撞的远程效应对天山陆内造山作用的起止时限、应力机制缺乏约束；对天山不同时期、不同构造单元隆升-剥露的差异性和阶段性认识不足。本项目拟以西天山不同地质单元的地质体为研究对象，以锆石和磷灰石（U-Th）/He和磷灰石裂变径迹等技术为主要手段，辅之含钾矿物40Ar/39Ar和锆石U-Pb技术，对西天山不同地质背景的地质体晚古生代以来剥露时间、温度、空间位置等进行综合研究，以期揭露天山造山带中-新生代的差异性隆升-剥露历史以及热演化史，了解其中-新生代构造演化过程以及驱动机制；结合青藏高原北缘和塔里木盆地周缘的热年代学研究成果，进一步揭露印度与欧亚大陆碰撞的远程效应对天山造山带陆内造山时空演化的作用，对深入认识中亚造山带中-新生代构造变形过程与机理有重要意义。

围绕天山和西准噶尔成矿带古生代俯冲、增生以及碰撞后的陆内造山带和矿床保存条件等科学问题并没有得到很好的约束。本项目以西天山不同构造单元的地质体以及土屋-延东斑岩铜矿和苏云河钼矿开展低温热年代学研究为重点，辅之对西天山造山带重要区域晚古生代侵入岩开展岩石地球化学研究，取得的主要成果如下：（1）揭露了天山造山带中-新生代剥露期次、机制和差异性剥露特征；（2）揭示了天山土屋-延东斑岩矿床的保存条件和控制因素：既早期的快速埋藏和晚期的缓慢剥露；（3）揭示了西准噶尔苏云河西准噶尔苏云河斑岩型钼矿的剥露和保存条件；（4）建立系统的岩石地球化学和同位素地球化学指标，厘定古亚洲洋俯冲带几何样式的完整演变与岩浆的时空响应，揭示增生造山带地壳侧向和垂向增生并存的生长机制。上述研究取得了一些创新性成果，在《Geological Society of America Bulletin》、《American Journal of Science》、《International Journal of Earth Sciences》、《Ore Geology Reviews》、《Journal of Asian Earth Sciences》和《岩石学报》等国内外著名刊物上发表论文13篇，其中国际SCI论文8篇。