皖南宁国大坞尖钨钼矿床成岩成矿年龄——以花岗闪长斑岩锆石U-Pb 和辉钼矿Re-Os 年龄为依据

    LA-ICP-MS zircon U-Pb age and molybdenite Re-Os dating of the Dawujian W-Mo polymetallic deposit, Ningguo, Anhui Province

    • 摘要: 大坞尖矿床位于钦杭成矿带东段北缘,是皖南地区典型的层控矽卡岩型矿床,矿床成岩成矿时代的确定对于该矿床成因研究及区域成矿规律认识具有重要意义。在详细的野外地质工作基础上,采集大坞尖矿床与成矿有关的岩浆岩样品和主成矿期的矿石矿物辉钼矿,分别利用LA-ICP-MS U-Pb和Re-Os同位素定年方法,获得岩浆岩的成岩年龄(148.3 ±2.2Ma、148.5±2.1Ma)和成矿年龄(144.4±1.5Ma)。通过区域对比,认为大坞尖矿床属于皖南地区燕山期第一阶段(150~136Ma)岩浆岩侵入的产物,该阶段是皖南地区重要的钨钼矿成矿时期,形成于古特提斯构造域向滨太平洋构造域转换过程中的区域挤压环境。

       

      Abstract: The Dawujian deposit is a typical stratabound skarn W-Mo deposit located on the northeastern margin of the Qin-Hang metallogenic belt. The determination of the ages of the mineralization and the magmatic rocks of the Dawujian deposit is very important for the study of deposit genesis and regional metallogenic regularity. On the basis of geological and petrographic studies, the authors collected the primary types of magmatic rocks and molybdenite of the main mineralization stage and obtained the ages of the magmatic rocks (148.3±2.2Ma, 148.5±2.1Ma) by LA-ICP-MS zircon U-Pb dating and the age of mineralization(144.4±1.5Ma)by Re-Os dating of the Dawujian deposit. The authors also reveal that the Dawujian deposit was formed by magmatite intrusion of the first stage of Yanshanian period(150~136Ma). This stage seems to be an important metallogenic period in the south of Anhui Province, which was formed in a regional compressional environment from the transform of the Paleo-Tethys tectonic domain to the Pacific tectonic domain.

       

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