宣化小营盘金矿的控矿构造研究

TECTONIC CONTROLS OVER THE DEVELOPMENT OFTHE XIAOYINGPAN GOLD DEPOSIT,XUANHUA,HEBEI PROVINCE

本文探讨了河北宣化小营盘金矿区的系列构造事件及相伴的变质－热事件，厘定了该区一条角闪岩相韧性剪切带以及稍晚的以剪切带中心为滑脱面的系列冲断构造。野外丰富的变形标志清楚地显示了这两期运动方向相反的构造事件的存在。显微构造亦十分丰富，并证实了这两期运动的存在及其先后关系。金矿主要以石英脉型式赋在于滑脱带，而顶、底板糜棱岩只有在冲断层切割处才显示含金石英脉。因此，笔者在小营盘金矿构造研究这一薄弱环节上有突破性认识，并指出控矿构造事件发生于中生代。基于此，对该区扩大找矿前景作者提出了有益的理论指导。

Detailed research has been made on tectonic events as well as the accom-panying metamorphism and 11eat events in the Xiaoyingpan gold ore distri-ct, Hebei Province. It is pointed out that there exists a ductile shear zone ofamphibolite facies and a seri`es of subsequent thnists gently dipping downinto a detachment surface lying in the central pazt of the shear zone. Further-more, plenty of defornlation suggests that the activities of these two diffe-rent tectonic deformations on different levels occurred in reverse directions.Thin section studies also confirm their existence and reveal their time relati-onship. Gold ore mainly occurs in the detachment zone with abundant spaceformed by lots of fractures and proper temperature; nevertheless, mylonitesin both haziging and lyizig walls of the detathment rarely contain auriferousquartz veins unless they are cut by thrusts. In view of some geological evidence on the North China plate affected by the Yangtse plato,it is thoughtthat these two different tectonic events took place in Mesozoic. Therefore,it isreasonable to hoid that our research has made a breakthrough in the study ofregional tectonics of this gold district. In the end, some useful suggestions aregivon to enlarge the area of the gold ore district. It is comidered that follow-up survey should be done in NW and SE diretions east of the Hujiaapoii faultand also in NW direction west of the fault.