青海五龙沟金矿成矿时代的进一步研究和确定

FURTHER STUDY AND DETERMINATION OF THE METALLOGENIC EPOCH OF WULONGGOU GOLD DEPOSIT IN QINGHAI PROVINCE

五龙沟金矿位于青海省东昆仑中段北缘,是东昆仑成矿带最具找矿潜力的金矿床.通过收集五龙沟地区金矿床成矿大地构造背景、区域地层、岩性、构造、岩浆岩等成矿特征方面的资料,首先采集同位素样品并用α石英活化定年（HAESRDQ）和Ar-Ar法对韧性剪切带围岩和金矿石进行了测年,对韧性变形时代、同构造碱性岩浆岩活动年龄、成矿物质源区年龄、金成矿年龄进行了逐一分析和研究,然后通过本次测得的数据年龄结合前人成果对五龙沟金矿成矿时代进行了综合确定.研究认为五龙沟地区韧性剪切带变形年代大致结束于240 Ma,即早—中三叠世的早印支期;金矿成矿的物源区年龄在235-179 Ma间的晚印支—早燕山期;成矿年龄为91-21 Ma的晚燕山期—早中喜马拉雅期.

The Wulonggou gold deposit, located in northern margin of the middle section of Eastern Kunlun Mountains in Qinghai Province, is the most prospective deposit in the Eastern Kunlun metallogenic belt. Based on collection of geologic data about the ore-forming tectonic setting, regional stratigraphy, lithology, structure and igneous rocks of Wulonggou gold deposit, with isotopic dating by alpha quartz activation （HAESRDQ） and Ar-Ar methods for gold ore and surrounding ductile shear zone, this paper analyzes the ages of ductile deformation, syntectonic alkaline magmatic activity, metallogenic material source and gold mineralization. By these data, with previous results, it is concluded that the ductile shearing deformation of Wulonggou area ended at about 240 Ma, namely Early-Middle Triassic or Early Indosinian epoch; the age of gold metallogenic material source area is between 235 Ma and 179 Ma, i.e., Late Indosinian-Early Yanshanian epoch; while the mineralization is dated at 91-21 Ma of Late Yanshanian to Early-Middle Himalayan epoch.