略阳地区泥盆纪地层中3T型多硅白云母的成因机理及找矿意义

3T型多硅白云母是白云母的一个变种。它不但是变质相带中的标型矿物,也是特球构造和板块消亡带的特征矿物。略阳地区泥盆系中3T型多硅白云母的发现在我省属于首次。该矿物发现于略阳县的西部,产于泥盆纪地层中金矿体内。金矿赋存于蚀变细碧岩中,共生矿物有石英、白云石、绿泥石、铁方解石、黄铁矿等。矿体含金品位增高时,3T型多硅白云母含量同步增长,而且地层扭动也随之强烈。本文对3T型多硅白云母产生的地质环境、矿物学特征,形成机理以及与构造运动、板块活动的关系等方面进行了初步探讨。

THE GENESIS OF THE 3T-TYPE PHENGITE IN THE DEVONIAN SYSTEM OF THE LUEYANG AREA AND ITS ORE PROSPECTING MEANING

The 3T-type phengite is a variety of muscovite.It is not only a typom- orphic mineral in metamorphic facies zone,but also a distinctive mineral occurring in special structures and the plate subduction zones.It is the first time to find the 3T-type phengite of the Devonian System in the Lueyang area. This kind of mineral,discovered in the western Lueyang County, occurred in gold orebodies of the Devonian strata,and the gold orebodies were developed in alteration spilite coexisting with quartz,dolomitite, chlorite,ferroan calcite and pyrite etc.The higher the gold content of the orebody is,the higher the 3T-type phengite content increases in same steps, and the more intensely the strata twist.In this paper,the writer has preli- minarily discussed the geological environment forming the 3T-type phengite, the minerological features as well as the relations of the genetic mechanism with the movements of structures and plate.