贵州镇宁泥盆系大型重晶石矿床地球化学特征及其成因研究

水城-紫云-南丹深断裂是跨越黔桂两省较为闻名的断裂带，沿断裂带两侧分布一系列矿床类型，贵州镇宁泥盆系大型重晶石矿床位于北西侧。对镇宁大型重晶石矿床的沉积学、地球化学及成矿背景的研究发现，矿石中发育纹层状构造、条带状构造、角砾状构造、碎屑状构造和厚层块状构造等热水沉积构造，常量元素特征揭示该矿床可能形成于以SiO₂及含矿硫酸盐流体的同生混合沉积作用。重晶石矿(岩)石中Sr、Zn和W明显富集，显示热水沉积特征，且该重晶石矿(岩)石在lg U-lg Th和Cr-Zr相关图解上也均显示热水沉积特征。稀土配分模式富集轻稀土，δEu表现正异常，δCe表现负异常，具热水喷流成矿特征。因此，认为镇宁大型重晶石矿属海底热水喷流沉积形成的产物。

Geochemical Characteristics and Genesis of Large Devonian Barite Deposits in Zhenning County,Guizhou Province

Shuicheng-Ziyun-Nandan deep fault is a well-known belt expanding across two provinces(Guizhou and Guangxi),along both sides distributing a series of diverse deposit types,and the large Devonian barite deposit is an important ore deposit in Zhenning County,Guizhou.The large barite deposit,located in the northwest margin of Shuicheng-Ziyun-Nandan deep fault was studied on the basis of the sedimentation characteristics,geochemistry and metallogenic background.The results revealed coexistence of a variety of hydrothermal water sedimentary structures characteristics such as laminar structures,barite-banded structure,brecciated structure,barite-fragmental structure,massive structure,and so on.Macroelement study indicated that the deposit was formed probably by synsedimentation of SiO2 and ore-bearing sulfate fluid.Besides,geochemistry of the large barite deposits of the Devonian shows the enrichment of Sr,Zn and W,strongly suggesting that the barite depo-sits is hydrothermal sedimentation in origin.The diagrams of lgU-lgTh and Cr-Zr in the barite deposit also present the features of hydrothermal sedimentation.According to the REE distribution pattern,LREE were enriched and Eu was positive while Ce was negative,which also shows a hydrothermal feature.As a result,we believed that the large barite deposits located in Zhenning formed by hydrothermal exhalative mineralization.