桂北中上元古界地球化学研究

STRATIGRAPHIC GEOCHEMISTRY OF UPPER-MIDDLEPROTEROZOIC SUBERATHEM IN NORTHERN GUANGXI

桂北中上元古界浅变质岩系为一套由活动型向稳定型转变的火山－陆源碎屑沉积建造，具有后太古代正常沉积砂泥质岩的岩石化学和稀土元素地球化学特征。其Ａｓ，Ｓｂ原始富集，Ｓｒ，Ｈｇ明显亏损，Ａｕ等成矿元素呈双峰或多峰分布，Ｓｎ，Ｃｕ，Ｎｉ，Ａｕ，Ａｇ，Ａｓ，Ｓｂ变异系数较大，属活动性强的元素．微量元素组合早期以亲铁、亲铜元素为主，晚期则出现亲石元素．桂北中上元古界发育以四堡群为基底原始含矿建造、丹洲群和下震旦统为盖层衍生含矿建造的演化系列。

The epimetamorphic series of rocks of Upper-Middle Proterozic Suberathem in NorthernGuangxi is a volcanic-terrigenous clastic sediment formation transforming from mobile phaseinto stable phase, petrochemistry and REE geochemistry of which are similar to Eparcheannormal argillo-arenaceous sedimentation.It is obvious for Upper-Middle ProterozoicSuberathem in Northern Guangxi as follows:original enrichment of As and Sb,significant depletion Sr and Hg,double or multiple populations of An content distribution,high variationcoefficients and strong mobilities of Sn,Cu,Ni,Ag,As and Sb,associations of siderophile andchalcophile elements occurring in Middle Proterozoic Subera and associations of lithophile elements occuring in Upper Proterozoic Subera.The authors suggest that in Northern Guangxi exists a evolutional series of synthetical ore-bearing formation which Sibao Group is theprotogenous basement,Danzhou Group and Lower Sinian Series are the derivative cap.