陕西镇安东阳钨矿床成矿时代及其地质意义

Geology and metallogenic epoch of Dongyang tungsten deposit occurring Zhenping County,Shaanxi Province

宁陕-镇安钨钼金多金属矿集区位处于南秦岭印支期褶皱带与燕山期北东向岩浆岩交汇部位,构造位置独特、岩浆活动频繁,孕育了类型丰富种类繁多的矿产资源。东阳钨矿床位于胭脂坝岩体北东向分支的懒板凳岩体与石瓮子组、两岔口组碳酸盐岩接触带附近。本文针对东阳钨矿床北东向伟晶岩型(长石石英脉型)钨矿体测得锆石U-Pb年龄为215.7±4.1Ma,指示其成矿时代为晚三叠世。暗示宁陕-镇安地区存在一次极为重要的印支晚期钨矿成矿事件,钨矿床的形成可能与区内印支晚期岩浆活动-成矿作用关系密切。

The Ningshan-Zhen'an tungsten molybdenum gold polymetalli concentrated zone is located at a structural junction between the Indosinian fold belt in the South Qinling Mountains and the Yanshanian northeast trending tectonic magmatic rock belt in Laoniushan-Yanzhiba area,where the unique tectonic location and frequent magmatic activities produced a rich and wide variety of mineral resources.The Dongyang tungsten deposit is located near the contact zone between the north-east trend Lanbandeng rock mass and carbonate rocks occurring in the Shiwengzi Formation and the Liangchakou Formation.Based on age determination of 215.7±4.1ma for zircon U-Pb in the NE trending pegmatite type(feldspar quartz vein type)tungsten ore body,the metallogenic age of the Dongyang tungsten deposit should be at the Late Triassic,which indicates that a very important tungsten mineralization event might occur in the Ningshan-Zhen'an area at the late Indosinian period and the formation of tungsten deposits should be closely related to the late Indosinian magmatic activity-mineralization in the area.