辽南丹东地区中生代金成矿的FIP证据

Mesozoic tectonic-hydrothermal activity driven gold metallogenesis in Dandong area, south Liaoning: evidence from FIP.

辽南丹东地区产出有五龙、四道沟两个大型金矿床。两矿床与中生代燕山期三股流花岗岩体存在密切的空间伴生关系。长期以来 ,对这一地区金的成矿作用时代存在有不同的认识。一种观点认为金的成矿作用只有一期 ,即中生代 (燕山期 ) ;另一种观点认为金的成矿作用有两期 ,即元古代和中生代 (燕山期 ) ,分别以四道沟金矿和五龙金矿为代表。作者利用流体包裹体面 (FIP)研究的新方法对金矿床及伴生花岗岩进行了研究 ,结果表明 ,三股流花岗岩的 FIP最优势定向方位与五龙金矿、四道沟金矿床含金石英脉的 FIP最优势定向方位一致 ;FIP中的流体是自下而上运移的 ;FIP中的流体是捕获于花岗岩成岩期和金矿床成矿期的流体 ;花岗岩的成岩与金矿床成矿流体形成于相同的区域应力场下 ,其捕获时间基本一致 ,与丹东地区的中生代构造热事件相吻合。 FIP的研究结果支持了丹东地区统一的中生代金成矿模式。实践证明 ,FIP是研究成矿作用的一种新的、有效的手段 ,在成岩、成脉 (矿 )

South Liaoning province, together with south Jilin province, east Shandong province, Xiaoqinling mountain areas in Henan province, and east Hebei province, are five large gold producing areas in North China Plateform. Important gold deposits in south Liaoning province are distributed in Dandong area. There are two typical and large gold deposits: Wulong gold deposit and Sidaogou gold deposit, respectively. Concerning with the gold mineralization epoch in this area, geologists hold two popular and different views. Some geologists favour two gold mineralization epochs: Proterozoic and Mesozoic mineralization epoch, whereas others prefer one mineralization epoch, that is Mesozoic minearalization epoch. The authors working on FIP reveal that (1) the trapping time for rock forming fluid from local granite is the same as the trapping time of ore forming fluid from the auriferous quartz veins in Wulong and Sidaogou gold deposits; (2) the rock forming fluid of granite and the ore forming fluid of gold deposits are all trapped under the same regional stress field; (3) the rock forming fluid of granite and the ore forming fluid of gold deposits can be related to the same Mesozoic tectonic hydrothermal activity in Dandong area. These data are in good agreement with the one mineralization epoch model: Mesozoic gold metallogenesis. In addition, this study also shows that the FIP method is a new but very efficient and helpful one in the research field of rock forming and ore forming processes .