安徽省笔架山绿松石矿床矿石矿物特征及矿床成因

安徽省马鞍山市境内分布一条典型的绿松石矿成矿带，其矿床成因一直存在争议。本次研究选取了该成矿带内笔架山绿松石矿床开展了详细的野外地质考察和室内观察，对绿松石矿石采用偏光显微镜、电子探针、扫描电镜（SEM）和ICP-MS等测试手段进行矿物学、岩石化学方面的分析与测试，并对与绿松石共生的黄铁矿进行了微量元素和δ³⁴S同位素测试。研究表明：绿松石矿床中矿石矿物为绿松石，并含少量石英、黄铁矿、高岭石、叶蜡石、褐铁矿和黄铁钾钒等矿物；绿松石为隐晶质集合体矿物，具变胶结构，SEM显示微晶集合体呈板片状平行或交错生长；与绿松石共生的黄铁矿具中低温热液成因的立方体、五角十二面体及其聚形晶形特征；在w（Ni）-w（Co）关系图中黄铁矿微量元素Co、Ni质量分数分布在岩浆和热液区；δ³⁴S_VCDT同位素（8.3‰~11.9‰）指示硫成矿物质来源于深部岩浆硫和沉积硫，成矿流体由大气降水和深部岩浆水混合而成。结合绿松石矿物组合、矿物生成顺序及共生黄铁矿成矿物质与成矿流体来源综合分析判断，该矿床为火山喷气活动形成的中低温热液蚀变交代（充填）型矿床。

Mineralogical Characteristics and Genetic Mechanism of Turquoise Deposit in Bijiashan Area in Anhui Province

A typical turquoise mineralization belt is distributed in Ma'anshan City of Anhui Province. The genesis of these turquoise deposits remains controversial. In this study, a detailed field geological survey and indoor observation of the Bijiashan turquoise deposits were carried out. The mineralogy and petro-chemistry of the turquoise minerals were analyzed by using microscope, electron probe, SEM, ICP-MS and other methods. The main minerals of Bijiashan turquoise deposit consist of turquoise with a small amount of quartz, pyrite, feldspars, pyrophyllite, limonite and jarosite. Turquoise is microcrystalline aggregate with gelatinous structure. The SEM micromorphology shows that the platelike crystallite aggregates of turquoise are parallel or staggered. The symbiotic pyrites with turquoise are characterized by medium-low temperature hydrothermal cubes, pentagonal dodecahedron and polymorphic crystal. In the chart of Co-Ni content relationship, the samples mainly distributed in magma and hydrothermal area. The δ³⁴S isotope ranges from 8.3‰ to 11.9 ‰, which indicates that the sulphur was derived from a deep magmatic and sedimentary source, and the ore-forming fluid was formed by mixed atmospheric precipitation and deep magmatic water. Combined with the mineral assemblage, mineral forming sequence, symbiotic pyrite mineralization, and ore-forming fluid, Bijiashan turquoise deposit is a medium-low temperature hydrothermally metasomatic deposit formed by volcanic eruption.