Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China.
Shandong Geological Sciences Institute, Jinan, 250013, China.
Sci Rep. 2017 Aug 10;7(1):7787. doi: 10.1038/s41598-017-08103-w.
The Sanshandao gold deposit contains an estimated Au resource of >1500 tons, however little is known about the history of exhumation, and the magnitude of displacement on the ore-hosting fault. Structural measurement revealed two phases of normal and one phase of sinistral movement on the fault. Despite of intra-sample dispersions, (U-Th)/He ages from two sub-vertical profiles show decreasing trends from the surface down to -3560 m (zircon: 123 Ma to 55 Ma; apatite 103 Ma to 0.3 Ma). Over-dispersion of AHe ages likely reflects the presence of undetected inclusions. According to the age-depth pattern, we infer that the deposit underwent an early phase of rapid cooling in the late Early Cretaceous, which was followed by a short period of thermal stagnation and a revived rapid cooling between 75 Ma and 55 Ma in response to a combined effects of late normal movement and erosion. Since the Eocene, the deposit has experienced a slow monotonic cooling. Exhumation magnitude estimates suggest that the deposit have been denudated > 5.1 km. The two phases of normal displacement along the fault occurred in the late Early Cretaceous and Late Cretaceous to Paleocene, leading to a total offset magnitude of 0.5-2.3 km.
三山岛金矿含有估计超过 1500 吨的金资源，然而，对于其抬升历史和含矿断层的位移幅度却知之甚少。构造测量揭示了断层上两期正常运动和一期左旋运动。尽管存在样品内离散性，但两个垂直剖面的 (U-Th)/He 年龄从地表向下呈现出逐渐降低的趋势（锆石：123Ma 至 55Ma；磷灰石：103Ma 至 0.3Ma）。AHe 年龄的过度分散可能反映了未检测到的包裹体的存在。根据年龄-深度模式，我们推断矿床在晚白垩世早期经历了快速冷却的早期阶段，随后在 75Ma 至 55Ma 期间经历了短暂的热停滞和复活的快速冷却，这是晚期正常运动和侵蚀的综合影响所致。自始新世以来，矿床经历了缓慢的单调冷却。抬升幅度估计表明，矿床已经被剥蚀了超过 5.1 公里。断层上的两期正常运动发生在晚白垩世和晚白垩世至古新世，导致总位移幅度为 0.5-2.3 公里。
