豫西嵩县上庄坪铅锌银矿床地球化学特征及地质意义

上庄坪铅锌银矿床是新一轮国土资源大调查中在北秦岭二郎坪群发现的硫化物矿床。笔者通过对矿床矿石、容矿同岩、重晶石岩的微量、稀土元素地球化学特征分析和地质特征研究,探讨成矿构造环境、成矿物质来源及矿床成因问题。研究表明.矿石和容矿围岩稀土元素球粒陨石标准化组成模式均为右倾型.矿石与围岩在Cu-Pb-Zn判别图解中投点区域一致.矿石Zn/(Zn Pb)与冲绳海槽和上向黑矿矿石特征相似、与TAG和EPR13°N区硫化物存在差异.矿石具较高As、Sb和Pb与低Cu、Cd和Se元素特征.认为该矿床成矿元素来源于壳幔混合、但以壳源为主的围岩变(石英)角斑岩和变细碧岩。矿石稀土元素、微量元素地球化学特征、矿床地质特征及与热水沉积重晶石岩和硅质岩的紧密共生关系说明,上庄坪矿床是弧后盆地构造环境海底热液喷流成岩成矿作用的产物。重晶石岩、硅质岩、矿床纵向和横向分带是寻找和勘探该类矿床的重要标志和依据。

Geochemical characteristics of the Shangzhuangping Pb-Zn-Ag deposit in Songxian County, western Henan, and its geological significance

The Shangzhuangping Pb-Zn-Ag deposit is one of the sulfide deposits found in the Erlangping Group in the North Qinling Mountains during the new round of land and resources survey.The tectonic setting, material source and genesis of the deposit are discussed by studying the trace element and REE geochemistry of ores,host rocks and barite rock and geological characteristics of the deposit.The study shows that:the chondrite- normalized REE patterns for ores and host rocks are right-inclined;the data points of ores plot in the same field as those of" the host rocks in Cu-Pb-Zn discrimination diagram;Zn/(Zn Pb)for ores of the Shangzhuangping deposit is similar to those for the Okinawa trench and Shangrdang kuroko-type ores but is different from those for sulfides in TAG and the EPR13~N region;ores display higher As,Sb and Pb and lower Cu,Cd and Se, which indicates that the ore elements of the deposit were derived from the country rocks meta-(quartz) keratophyre and meta-spilite generated by crust-mantle mixing but mainly crustal rocks.The trace element and REE geochemistry of ores,geology of the deposit and their close paragenetic relationship with hydrothermally deposited barite rocks and cherts suggest that the Shangzhuangping Pb-Zn-Ag deposit was formed by submarine hydrothermal exhalative petrogenesis and mineralization in the back-arc basin environment.Barite rock,chert and vertical and lateral deposit zoning are important criteria for looking and exploring for such Pb-Zn-Ag deposits.