湖南黄沙坪矽卡岩矿物学特征及地质意义

湘南黄沙坪多金属矿床位于南岭构造带中段北缘，属于矽卡岩型矿床。根据矽卡岩产出状态、矿物共生组合及岩相学特征，从早期到晚期可划分为矽卡岩阶段、退化蚀变阶段、早期硫化物阶段和晚期硫化物阶段。矽卡岩矿物主要为石榴石、辉石、符山石等；金属矿物主要为白钨矿、辉钼矿、磁铁矿、方铅矿、闪锌矿等。电子探针分析结果表明，石榴石为钙铝-钙铁榴石系列，从早期到晚期，石榴石具有由钙铝榴石逐渐向钙铁榴石演化的规律。且钙铁榴石普遍发育震荡环带，而环带结构可持续记录钙铁榴石物理化学条件演化的过程。同时两种石榴石中均含Sn的成分，但钙铁榴石中Sn的含量明显高于钙铝榴石。辉石为透辉石-钙铁辉石系列，而且由内接触带向外接触带，辉石中Fe和Mn的含量有逐渐升高的趋势。矽卡岩矿物学特征及矿物成分的变化表明，成矿流体至少经历了两次氧化还原性质的转变。矽卡岩矿物学特征，对W(Sn) Mo Bi等多金属的矿化具有重要的地质指示意义。

Skarn Mineral Characteristics and Their Geological Significance of the Huangshaping Deposit in Hunan Province

The Huangshaping polymetallic deposit is a skarn deposit, which lies on the northern margin of the middle Nanling tectonic belt. According to the output state of skarn, mineral assemblage and characteristics of petrography, the stage of mineralization is divided into skarn stage, retrograde alteration stage, the early and the late sulfide stage. The skarn minerals are mainly garnet, pyroxene, vesuvianite. Metallic minerals mainly include scheelite, molybdenite, magnetite, galena and sphalerite. The electron microprobe analysis(EPMA)result shows that the garnets forming in the skarn stages are mainly andradite grossularite series and garnets vary from grossularite to andradite. The andradites commonly have zonal structure which can record the evolutionary process of physicochemical conditions. The andradite and grossularite both contain Sn, but the content of Sn in the former is higher than the latter. The pyroxenes are mainly diopside hedenbergite series, and the content of Fe and Mn has a rising trend from the internal contact zone to the external contact zone. Mineralogical characteristics and compositional variations suggest that the property of fluid changed with two redox fluctuations at least. Skarn mineralogy characteristics is of important geological implications of W(Sn) Mo Bi polymetallic mineralization.