新疆西准噶尔苏云河斑岩型钼矿的剥露和保存条件:来自裂变径迹和(U-Th)/He热年代学的约束

斑岩型矿床多形成于汇聚型板块边界.由于其较浅的就位深度,大部分古老的斑岩型矿床很容易受到后期的剥蚀而消失殆尽.研究斑岩型矿床成矿后的埋藏和去顶过程对于深入理解矿床的保存条件和区域找矿前景至关重要.新疆西准噶尔西部的苏云河斑岩型钼矿床形成于晚石炭世,是一处保存良好的斑岩型矿床,为我们研究前中生代斑岩成矿系统的保存条件提供...

Exhumation and preservation conditions of Suyunhe porphyry molybdenum deposit in the West Junggar, Xinjiang (NW China): Constraints from the fission track and (U-Th)/He thermochronology

Porphyry deposit is a kind of epithermal deposit, which is mostly formed in the convergent plate boundary. However, ancient porphyry deposit was often destroyed and disappeared due to later tectonic or exhumation. Therefore, it is vital to reveal the exhumation and uplift process after mineralization for further understanding the preservation conditions and regional prospecting prospects of the deposits. Suyunhe porphyry molybdenum deposit in the west part of the West Junggar, Xinjiang was formed in Late Carboniferous. It is a well-preserved porphyry deposit, which provides a natural laboratory for us to study the preservation conditions of ancient porphyry metallogenic system. In this paper, we present new zircon and apatite fission track (ZFT and AFT) and zircon (U-Th)/He (ZHe) data for the Suyunhe porphyry molybdenum deposit. Combined with thermal modeling inversion, we suggest that the hydrothermal alteration process of the Suyunhe porphyry molybdenum deposit lasted at least 55Myr. It underwent a thick burial (5.2~8.1km) sediments from Early Permian to Middle Triassic. The deposit experienced a rapid exhumation stage from Middle Triassic to Early Cretaceous (240~120Ma). The exhumation rate was 49.0~56.7m/Myr, and the corresponding denudation amount was 7.4~9.2km. After the Cretaceous (120Ma), it entered a slow exhumation stage with an exhumation rate of 6.7~21.7m/Myr and exhumation amount of 0.8~2.6km. Among them, the Middle Triassic to Early Cretaceous rapid exhumation was not the product of far-field effects (e.g., the collision between Qiangtang and Kunlun-Qaidam or the collision between Qiangtang and Lhasa), but related to the activation of strike slip faults in the region. Therefore, early thick burial and later dry climate and slow exhumation provided key conditions for the preservation of the Carboniferous Suyunhe porphyry molybdenum deposit.