广西大厂矿区脉岩的地球化学特征及其构造和成矿意义  

Geochemical Features of Vein Rocks and Their Significance to Structure and Mineralization in the Dachang Ore District,Guangxi Province

作　　者：范森葵[1,2] 黎修旦[3] 成永生[4,5] 陈承珍 黄伟洪 

机构地区：[1]中南大学地学与环境工程学院,长沙410083 [2]广西215地质队,柳州545000 [3]广西国土资源厅,南宁540001 [4]中南大学信息物理工程学院,长沙410083 [5]广西华锡集团股份有限公司,柳州545005

出　　处：《地质与勘探》2010年第5期828-835,共8页Geology and Exploration

基　　金：国家科技支撑项目(编号:2006BAB01B03);国土资源部危机矿山专项(编号:200545022)资助

摘　　要：位于丹池成矿带的大厂锡矿是我国著名的超大型锡多金属矿田和重要的锡矿产出地。大厂矿区的花岗斑岩和(石英)闪长玢岩脉岩,位于主要矿床的两侧,成群成带分布。花岗斑岩和闪长玢岩是在燕山晚期黑云母花岗岩之后同期或充填时间前后相差不大形成的。花岗斑岩和闪长玢岩均穿过矿体,与围岩的接触带内包含围岩角砾和矿化。花岗斑岩的SiO2、Al2O3、CaO和MgO含量较高,K2O+Na2O含量较低。岩石的氧化度较低,暗示成岩部位较深,属相对还原的成岩环境,其侵位固结前经过充分的演化分异,对成矿有利;闪长玢岩具有碱、铝、钛、镁、铁含量都较高的特点,岩石的氧化度较高。脉岩来源于地壳的重熔;脉岩沿南北向断裂充填形成,侵入时间晚于成矿期;矿床分带特征与脉岩的成岩环境一致;脉岩中丰富的主成矿元素和微量元素及其变化趋势,表明其提供了成矿物质或者其所充填的断裂曾是矿液运移通道,在成矿后才被充填,脉岩本身也为成矿物质提供了来源;石英闪长玢岩具有埃达克质岩特征,可能是由底侵的玄武质下地壳熔融形成,推测有底侵的玄武质下地壳熔融形成的岩浆参与岩脉旁侧多金属矿床的成矿。The Dachang tin deposit,which is situated at the Danchi metallogenic belt,is one of the most famous superlarge tin-polymetallic deposit and the important tin output base in China.In the Dachang mining area,granite-porphyry and quartz diorite porphyrite vein rocks are located mainly on both sides of the deposit,which are distributed in swarms and belts.The granite-porphyry and diorite porphyrite formed synchronously or successively with a small lag after the biotite granite formed in the late Yanshan period.The granite-porphyry and diorite porphyrite,which contain wall rock breccia and mineralization material in the contacting zone,cut through the orebody.It is characterized by high content of silica,alumina oxide,calcium oxide,magnesium oxide and low K2O＋Na2O for granite-porphyry.The low oxidizability of rock suggests the deep diagenesis site and the reducing environment of diagenesis,which experienced complete evolution and differentiation and was favorable to mineralization.Diorite porphyrite,which was highly oxidized,has high content of alkali,aluminum,titanium,magnesium,and iron.The tectonic environment of vein rocks originated from earth crust remelting,belongs to regional tension.The formation of vein rocks filled with N-S trending fractures was later than the mineralization.The zoning of deposit is the same as the vein rocks.The rich main mineralizing elements,trace element and their changing trend of vein rocks suggest that the vein rocks supplied a part of metallogenic material,or the filled fracture was the migration channel of ore fluid and was filled after mineralization,which has important significance for deposit generation.And the vein rock was also the ore source.Quartz diorite porphyrite is characterized by adakitic rocks,which might be from the underplating basaltic lower crust and involved in mineralization of the polymetallic deposit near the dykes.

关 键 词：大厂矿区 脉岩 地球化学特征 构造与成矿意义 

分 类 号：P618.4[天文地球—矿床学] P588.13[天文地球—地质学]