冀西北东坪金矿床含金石英脉石英流体包裹体Rb-Sr等时线及其地质意义

Rb-Sr ISOCHRON DETERMINATION FOR FLUID INCLUSIONS WITHIN QUARTZ VEIN FROM DONGPING GOLD DEPOSIT, NW HEBEI PROVINCE AND ITSI MPLICATIONS FOR METALLOGENY

用石英流体包裹体Ｒｂ－Ｓｒ等时线法测得产于碱性岩体中具有超大型潜力的东坪金矿床含金石英脉的年龄为（１０３±８）Ｍａ，远晚于赋矿岩体的就位时间（元古宙），显示了成岩与成矿是两期不同构造运动的产物，两者之间没有直接的成因联系。８７Ｓｒ／８６Ｓｒ示踪结果显示成矿物质主要来源于赋矿碱性岩体。研究结果认为，东坪金矿是后期与大气降水热液有关的改造成矿作用的产物。

In order to understand the genesis of oredeposits,it is fundamental to know the timing of gold deposition.Dongping gold deposit,occurred in alkaline intrusions and with super-large scale potential,is dated by Rb-Sr isochron for fluid inclusion within quartz vein at (103±8) Ma.This age is significantly youngert han that of emplacement of its host intrusions (Middle Proterozoic), precluding the direct genetic link between gold mineralization and alkaline magmatism.Initial 87 Sr/ 86 Sr ratios suggest that ore-forming materials of Dongping gold deposit were derived predominently from the hostrocks.It is,therefore,concluded that Dongping gold deposit is not traditionally magmatic hydrothermal genesis,but the product of reworked mineralization related to meteoric water long after the formation of alkaline intrusion.