西藏甲玛斑岩-矽卡岩型矿床隆升剥露历史研究

The research on the uplift and exhumation history of the Gangdese Porphyry Copper Belt not only have practical significance on the knowledge of preservation potential and distribution regularities of the deposits in the belt, but also have scientific significance on the cognition of Cenozoic uplifting history of the Tibetan Plateau and climate change. However, the insufficient studies and understandings on the Gangdese Porphyry Copper Belt and the lack of detailed studies of major porphyry deposits induced the long-standing dispute on the ore deposit preservation potential and distribution regularities. This study take the Jiama porphyry-skarn copper polymetallic deposit, one of most important deposit in the belt, as an example, and will focus on the low temperature chronological studies of the samples from a 3000 m deep drilling hole and other holes <1500 m. Systematic fission track and (U-Th)/He dating on the vertical profile, and thermal modeling will be employed to reconstruct the uplift and exhumation progress of the Jiama deposit and its mechanism. In the meantime, this study will further discuss the preservation conditions of ore deposits in the Gangdese Porphyry Copper Belt. The results will provide an important scientific evidence for understanding the temporal and spatial distribution of ore deposits in the Gangdese Porphyry Copper Belt and the uplifting process of the Tibetan Plateau.

冈底斯斑岩铜矿带矿床隆升剥露历史研究不仅对认识成矿带矿床保存条件和分布规律具有实践意义，而且对认识整个青藏高原新生代隆升历史和气候环境变化具有重要的科学意义。然而目前对成矿带及典型矿床的隆升剥露历史研究和认识程度较低，导致对成矿带矿床保存和分布规律长期存在争议。本项研究以成矿带重要的甲玛斑岩-矽卡岩型铜多金属矿为解剖对象，以矿区3000m科学深钻和1500m以浅的钻探岩芯低温热年代学研究为主要方法，通过垂直剖面上系统的裂变径迹和(U-Th)/He年代学研究，结合热历史模拟，在恢复甲玛矿床隆升剥露过程与机制的同时，探索成矿带矿床保存条件，研究结果将对认识冈底斯斑岩铜矿带矿床时空分布规律和高原隆升过程提供重要的科学依据。

隆升-剥蚀历史研究对冈底斯成矿带斑岩型矿床时空分布规律、保存条件及制约机制的揭示至关重要。本项研究以成矿带重要的甲玛斑岩-矽卡岩型铜多金属矿区3000m科学深钻岩芯和带内高海拔地区始新世岩体为主要研究对象，开展垂直剖面上低温热年代学研究，厘定了冈底斯成矿带中新世快速剥蚀历史、限定了甲玛成矿岩体侵位深度、成岩成矿后剥蚀量及剥蚀历史；发现冈底斯渐-中新世斑岩型矿床时空分布特征受谢通门-沃卡剪切带活动控制、冈底斯渐-中新世斑岩成矿系统保存作用归功于受错纳裂谷活动控制的区域侵蚀基准面显著抬升作用，以上认识对冈底斯成矿带找矿预测具有指导意义；同时，通过3000m科学深钻低温热年代学研究发现冈底斯东段~15Ma以来地温梯度为~20℃/km，填补了研究区古地温梯度的空白，对高原中新世以来隆升-剥蚀作用研究提供重要依据。