广西龙围地区石英脉型铜矿中硫化物Re-Os测年及意义

广西大瑶山西北地区有大量的石英脉型铜矿出露,然而缺少相关矿床年龄的研究。为解决该问题,选取广西金秀龙围地区石英脉型铜矿床矿石中的黄铁矿和黄铜矿,进行Re-Os同位素测年研究,获得了加里东期的黄铁矿等时线年龄(417±25) Ma(MSWD=0.92)和印支期的黄铜矿等时线年龄(243±18) Ma(MSWD=0.45)。黄铁矿结晶明显早于黄铜矿,加里东期是否存在成矿事件还需要进一步研究。结合岩石矿物学分析,我们认为龙围地区铜矿床中矿石的形成,经历了黄铁矿结晶、黄铁矿碎裂和含铜热液在印支期充填交代等过程,最终固结成矿。研究厘定了龙围地区铜矿的成矿时间,并为大瑶山西北地区存在印支期成矿热液活动提供了证据。

Age-dating of Sulfide Re-Os in Quartz Vein-type Copper Deposits in Longwei Area,Guangxi and Its Significance

There are a large number of quartz vein-type copper deposits exposed in northwest Dayaoshan, Guang- xi,but there is a lack of research on the age of related mineral deposits. To solve this problem, the paper selects pyrite and chalcopyrite in quartz vein-type copper deposits in Jinxiu Longwei area for Re-Os isotopic age-dating research. It is concluded that the isochron age of pyrite is (417±25) Ma (MSWD=0.92), which belongs to Caledonian period; the isochron age of chalcopyrite is (243±18) Ma (MSWD=0.45), which belongs to Indosinian period. Pyrite crystallization is obviously earlier than chalcopyrite, and whether there are metallogenic events in Caledonian period needs further study. In combination with rock mineralogical analysis, we think that the mineralization in the copper deposits in Longwei area experienced the processes of pyrite crystallization, pyrite fragmentation and copper-bearing hydrothermal solution filling and metasomatism in Indosinian period, and finally consolidated into mine. The metallogenic time of copper deposits in Longwei area was determined in the research, which provided evidence for the existence of metallogenic hydrothermal event in Indosinian period in the northwest of Dayaoshan.