湖南新宁变种独居石主要特征及其找矿意义

The Main Features and Prospecting Significance of the Variant Monazite in Xinning Hunan

湖南新宁县万塘地区的溪流重砂中发现了独居石矿物的新类型—变种独居石,其赋存地层单位为上泥盆统佘田桥组—下石炭统梓门桥组,赋存岩性主要为暗色粉砂质页岩、硅质页岩和薄层泥灰岩。变种独居石除产状和形态较为特殊外,其他特征与普通独居石相差不大。经沉积时代和岩相古地理分析,发现万塘西南方向的苗儿山岩体在晚泥盆世—早石炭世处于局限台地相和滨海沼泽相区内,接受不稳定剥蚀,变种独居石正是由此时期内苗儿山岩体所含的青白口纪花岗岩和志留纪花岗岩经剥蚀搬运后沉积形成。变种独居石中稀土元素含量较高,通过探讨新宁变种独居石的发现及成因,寻找陆地边缘相区和局限台地相区环境改造过的花岗岩岩体,可将其周边的局限台地相或者开阔台地相沉积中的变种独居石的探寻作为寻找稀土矿物的一种新途径。

People found a new type of monazite- variant monazite in heavy-mineral from Wantang,Hunan.It exist in upper devonian and lower carboniferous, attach to dark silty shale, siliceous shale and thin marl. Variant monazite is differ with the ordinary ones:in late devonian and early carboniferous, Miaoer mountain rock mass located in restricted platform facies and coastal marsh facies.After erosion、transport and sedimentation, the granites of qingbaikouan period and silurian period in Miaoer mountain rock mass remained the variant monazite.Rare earth elements are high in monazite,so we can found rare earth minerals through the searching of variant monazite in restricted platform facies or open platform facies near the granites remoulded by continental marginal facies and restricted platform facies.