德兴大型铜金矿集区的研究进展和成矿模式

The research advances and genetic model of the giant Dexing Cu-Au ore cluster

德兴大型铜金矿集区是我国最重要的铜金产地之一。多年来,德兴矿集区的成矿过程和成因模式一直引起广大地质学家的广泛关注。在前期大量的野外工作观察和多年研究基础上,结合前人的研究成果,本文提出德兴矿集区由两套成矿系统组成:新元古代金山-水石坞-西蒋-渔塘-蛤蟆石-上洛造山型金成矿系统和燕山期德兴和银山斑岩-浅成低温热液型铜金多金属成矿系统。德兴矿集区的造山型金矿可进一步划分为两个亚系统,分别为对应于区域NW向推覆构造的NWW走向、缓倾斜的金山金矿田超糜棱岩型亚系统(约为840Ma),和对应于区域上NE向走滑剪切运动的NE走向、陡倾斜的蛤蟆石金矿田和金山金矿阳山矿段的石英脉型亚系统(约为750~710Ma)。造山型金矿的成矿物质来自富金的新元古代双桥山群基底地层,成矿流体主要为富CO2的变质流体。燕山期斑岩-浅成低温热液系统的形成时代为约170Ma,此时古太平洋板块开始向华南大陆俯冲,导致赣东北深大断裂活化,引发新元古代形成的富铜金的初生地壳重熔再造,形成德兴Cu-Au-Mo矿和银山Cu-Au-Pb-Zn-Ag矿,成矿热液主要来自于岩浆流体来源的贫CO2的NaCl-H2O体系。

The Dexing ore cluster is one of the most important Cu-Au production bases in China. Over the years,its metallogenic process and genetic model have been widely concerned by the geologists. On the basis of a large number of field observations and years of research,combined with the previously published results,we propose that the Dexing ore cluster is consisted of two different metallogenic systems: the Neoproterozoic Jinshan-Shuishiwu-Xijiang-Yutang-Hamashi-Shangluo orogenic gold system and the Yanshanian Dexing-Yinshan porphyry-epithermal Cu-Au polymetallic system. The orogenic gold ore system in Dexing ore cluster can be further divided into two sub-systems,namely the NWW striking,shallowly dipping ultramylonite type gold subsystem in the Jinshan gold ore field( ca. 840 Ma) and the NE-trending,steeply dipping quartz vein type gold subsystem including the Hamashi ore field and the Yangshan section of the Jinshan gold deposit( ca. 750 ~ 710 Ma). They correspond to the regional NW-trending thrusting event and the NE-trending strike-slip movement,respectively. The ore-forming materials of the Neoproterozoic orogenic gold metallogenic system are derived from the basement strata of the gold rich Shuangqiaoshan Group. The ore-forming fluids are mainly CO2-rich metamorphic fluids. The Dexing Cu-Au-Mo and the Yinshan Cu-Au-Pb-Zn-Ag deposits constitute the Yanshanian porphyry-epithermal hydrothermal system( ca. 170 Ma). The ore-forming materials are mainly derived from partial melts of the Cu rich continental crust,due to the reactivation of the northeastern Jiangxi deep fault in response to the initial subduction of the paleo-Pacific plate beneath the South China. The ore-forming fluid is a CO2-poor NaCl-H2O system,which mainly comes from the magmatic hydrothermal fluid and the involvement of the meteoric water.