广西老厂铅锌矿床地质特征及其成因探讨

本文是在专题研究基础上,探讨广西老厂铅锌矿床地质特征和矿床成因。该矿床位于海洋山复式背斜南段的老厂穹窿构造核部,铅锌矿化受构造、地层和岩性控制。矿体呈脉状,产于NE向组张扭性断裂构造中;围岩为寒武系白云岩,板岩、砂岩;矿石类型以锌为主,矿物成分简单,以闪锌矿、方铅矿与石英、白云石为主,具充填、交代矿石结构、构造,矿石平均品位含Zn9.94%、Pb1.50%;围岩蚀变主要为硅化、绢云母化和碳酸盐化。据地层岩石元素丰度值、稀土元素配分和稳定同位素数据、资料,探讨了成矿物质来源于围岩,热液主要来自大气降水。因此,认为本矿床实属产于寒武系轻变质岩中的层控矿型大气降水热液铅锌矿床。

ON THE GEOLOGICAL CHARACTERISTICS OF LAOCHANG LEAD-ZINC DEPOSIT IN GUANGXI AND ITS GENESIS

The geological characteristics of Laochang Pb-Zn deposit in Guangxi and its genesis are discussed in the paper on the basis of monographic study. The deposit is situated at the core of Laochang dome of the southern section of Haiyangshan anticlinorium and its Pb-Zn mineralization is controlled by structures, strata and lithology. The country rocks are Cambrian dolomite, slate and sandstone. Orebodies occur as vein in NE-trending tenso-shear fractures. The ore is mostly composed of sphalerite, galena, quartz and dolomite and possesses filling and metasomatic texture and structure. The average ore tenor is that Zn makes up 9. 94% and pb 1. 50%. The wallrook alterations are silicification, sericitization and carbonatization. The abundance of rockforming elements strata, the distribution of rare earth elements and the data of stable isotopes show that the ore-forming material was derived from the country rocks and the hydrothermal solution from meteoric water. Therefore, the deposit is actually considered as a stratabound-type meteoric-hydrothermal Pb-Zn deposit which occurs in the Cambrian slightly metamorphosed rocks.