西准噶尔成矿带剥露过程的热年代学制约

Ore deposit study includes both deposit genesis and preservation. Deposit genesis study has made great progress in the last hundred years. The application of (U-Th)/He, fission track and 40Ar/39Ar thermochronometry methods to mineralized systems has already been widely accepted. Whereas, the analytical technique and application research of (U-Th)/He dating in China are lagging far behind, which, as a consequence, is strangling its wide application in ore deposits. Recently, along with the establishment and improvement of domestic (U-Th)/He laboratory, it will promote potentially application research of Chinese thermochronometry in the exhumation and uplift history of ore deposits. The West Junggar has become a hot study area for ore prospecting and metallogenic model, however, the timing of post-mineralization processes, such as thermal history, exhumation and erosion, lacks well-documented constraints. In this project, we will investigate the ore-bearing-porphyries (e.g. Baogutu porphyry copper deposit) of the West Junggar metallogenic belt and utilize multiple thermochronometers (zircon U/Pb, 40Ar-39Ar、Fission Track, (U-Th)/He dating) to reveal the timing of formation and hydrothermal activities of ore deposits, and to elucidate the thermal history, exhumation and erosion (including timing, rate, episode, etc.) by multiple thermal history modeling (e.g. thermal history modeling, age-elevation relationship, age-closure temperature and mineral-pair method) since late Paleozoic.

矿床学研究包括矿床成因和保存两方面。近百年来，矿床成因研究已经取得重要的进展。在国际上，应用(U-Th)/He等技术来约束矿床剥露-隆升历史已得到普遍认同。但是我国(U-Th)/He分析技术研究起步较晚，也阻碍了相关学科的发展。目前，随着国内相关(U-Th)/He实验室的建立和完善，有望促进我国低温热年代学技术在矿床剥露和抬升历史中研究。西准噶尔地区目前己经成为一个集找矿研究与成矿模式研究的热点地区，但其成矿后所经历的热演化历史缺乏有效的约束。本项目拟对西准噶尔地区含矿斑岩（如包古图铜-金矿）、岩墙、中酸性侵入岩为研究对象，运用多体系同位素热年代学分析手段（如：裂变径迹，(U-Th)/He定年），约束矿床的形成和热液活动时限；通过精细的多元热史模拟（如：年龄-封闭温度法、矿物对法等方法），确定西准噶尔成矿带晚古生代以来热演化历史和隆升-剥露历史，并给出活动的时间、速率和期次等定量数据。

矿床学研究包括矿床成因和保存两方面。西准噶尔和天山成矿带是中国新疆最重要的找矿研究与成矿模式研究的热点地区，但其热液活动时限，矿床的保存条件和揭顶机制等缺乏有效的约束。本项目以新疆包古图和土屋-延东斑岩铜矿为研究重点，辅之对西准噶尔和天山地区重要剖面的侵入岩开展岩石地球化学和多体系同位素热年代学研究，取得如下成果：（1）揭示了西准噶尔包古图斑岩铜矿的热液蚀变时限、多阶段的冷却和揭顶过程；（2）识别出西准噶尔多期快速冷却事件，重建其剥露-隆升过程；（3）揭示了土屋-延东斑岩矿床得以保存的条件和关键因素，早期快速，巨厚埋藏和晚期缓慢剥露；（4）揭示了古亚洲洋俯冲过程的复杂性和多样性；（5）识别出天山造山带陆内造山过程的多期性和空间差异性以及与区域构造事件的耦合关系。以第一作者身份在GSA Bulletin，Tectonophysics，Gondwana Research和Ore Geology Reviews等刊物发表论文14篇，其中国际SCI论文10篇。