广西南源洞硅灰石矿床地质特征及成因

The Geological Characteristics and Genesis of Wollastonite Deposit in Nanyuandong,Guangxi

硅灰石矿体产出在石英二长岩外接触带下石炭统岩关阶硅质灰岩特定的地层中。成矿作用以接触热变质作用为主并伴随接触交代作用的叠加。硅灰石的形成主要是硅质灰岩中的Ｏ、Ｓｉ、Ｃａ在岩浆热源条件下固相扩散就地重新组合的产物。硅质灰岩中的ＳｉＯ＿２＞３５％是形成矿区硅灰石富矿的必要条件。矿石平均化学成分ＳｉＯ＿２５２．１７％、ＣａＯ４１．２９％、Ｆｅ＿２Ｏ＿３０．６１％、ＭｎＯ０．０７４％；矿石中矿物平均含量硅灰石（Ｗｏ）７３．６３％、石英（Ｑ）９．５７％、透辉石６．７５％、方解石５．６６％、石榴石（Ｇｒ）２．１４％；矿石属Ⅰ级品矿石，可用于建筑陶瓷工业。

The wollastonite ore body occure in the exo-contact zone of quartz monzonite, the host rockis Yanguan Formation siliceous limestone of Lower Carboniferous. The mineralization take placemainly the thermal contact metamorphic mineralization and superimposition by subsequent con-tact metasomatic metamorphism. The wollastonite is formed by recomposing of solid-spreading ofO,Si,and Ca in the siliceous limestone under the condition of magma heat resources. The neces-sary conditions formed the rich deposit of wollastonite in mining is that the content of SiO_2 inlimestone is larger than 35 percent. The average chemical composition of the ore(%)givesSiO_252. 17%,CaO41. 29,Fe_2O_30.61,MnO0. 074. The average contents of the minerals in ore(%)gives Wollastonite(Wo)73. 63,Quartz(Q)9. 57,Diopside(Di)6. 75,Calcite(Ca)5. 56, Gai-net(Gr)2. 14,The ore is Ⅰ grade-ore,It can be used in buildinsand cermic material.