湖北大悟大磊山金矿矿床成因与控矿构造

Origin and ore-controlling structure of the Daleishan gold deposit in Dawu area,Hubei Province

在翔实的野外地质工作基础上,对湖北大悟大磊山金矿床进行矿区填图,并结合前人研究成果,充分分析大磊山金矿的控矿构造及矿床成因,认为该金矿导矿、配矿构造是一种新的构造类型,二者均不是断裂构造,而是燕山期区域广泛的岩浆活动使得大磊山花岗岩穹窿上隆,导致围岩沿接触面下滑,形成剪切带,该剪切带为后期热液提供了导矿、配矿通道;新元古代片麻状二长花岗岩为金矿提供了较高的金元素背景值,燕山期岩浆活动不但使金元素活化、迁移,也为金矿成矿提供了物质来源,金矿的矿床成因是中低温岩浆期后热液矿床;根据含金石英脉充填煌斑岩脉裂隙的地质特征,利用LA-ICP MS锆石U-Pb定年法获得了煌斑岩成岩年龄为126.8±2.0 Ma,从而限定了大磊山金矿成矿年代。

The authors conducted mapping in the mining area on the basis of detailed field geology and, in combination with the previous research results, fully analyzed gold ore-controlling structures and genesis of the Daleishan deposit. It is held that the ore-guiding and matching structures of the gold deposit belongs to a new type, and both structures are not fault, but belong to the formation of shear zone formed by upward migration of the Daleishan granite dome caused by magmatic activity during the Yanshanian epoch, which provided the channel for late ore-guiding structure and matching structure; Neoproterozoic gneissic monzogranite provided the gold with higher gold element background values for the gold deposit, and magmatic activities not only caused the activation migration of gold element but also provided the gold metallogenic material source. The gold ore deposit was a post-magma low temperature magmatic hydrothermal deposit. According to the geological feature that the gold quartz vein fills in the crack of lamprophyre, the authors used LA-ICP MS zircon U-Pb dating and obtained a lamprophyre diagenetic age of 126.8±2.0 Ma, which confined the mineralization age of the Daleishan gold deposit.