江西省德兴市铁罗山金矿床地质特征及找矿远景

Geological Characteristics and Prospecting Potential of Tieluoshan Gold Deposit in Dexing County,Jiangxi Province

铁罗山金矿是在德兴铜矿北部首次发现的独立矿床,该矿床的发现丰富了花岗斑岩体外围的金矿成矿理论,并开启了在该铜矿北部找金的序幕。结合相关地质工作成果,分析了成矿地质背景、矿区及矿床地质特征、矿床成因,研究表明:(1)矿床处于赣东北韧性剪切蛇绿岩构造混杂岩带中,近EW向展布的杜村背形与NNE向陡倾斜断裂构成了矿区的基本构造格架,控制着矿区成矿、容矿构造——大坞坂韧性剪切变形带的产出;(2)大坞坂韧性剪切带在形成及演变过程中,带内构造岩及其近侧围岩均遭受不同程度的蚀变,其中与金矿化关系密切的主要有绢云母化、硅化、黄铁矿化、方铅矿化、铁白云石化、褪色化等;(3)矿区可划分为石英-绢云母-黄铁矿-铁白云石化带(Qtz-Ser-Py-Fer)、绿泥石-方解石-绢云母化带(Chl-Cal-Ser)等两个构造蚀变带;(4)矿床具有多阶段演化、多因复成的特点,历经火山沉积、区域变质、动力变质及岩浆热液叠加富集等成矿过程,矿床成因为受韧性剪切带控制的变质热液型金矿床。在上述分析的基础上,进一步讨论了找矿标志及找矿远景,分析认为:(1)矿床构造位置及其蚀变构造岩组合、赋矿地层及岩石组合、与金矿化关系密切的围岩蚀变组合均为有利的找矿标志;(2)杜村背形与NNE向断裂交汇形成的断陷带为"铁罗山"式金矿找矿远景区,此外,矿区深部钻孔中绿泥石化增强,金属硫化物增多,表明区内深部成矿热液作用将会增强,更深部可能存在铜金复合矿体。

Tieluoshan gold deposit is the independent gold deposit that is found firstly in north of Dexing copper deposit,the gold metallogenic theory of porphyry granite periphery is enriched by the foundation of Tieluoshan gold deposit, and the gold prospecting work of the north of Dexing copper deposit is activated. Combing with some related geological working results of Tieluoshan gold deposit, the metallogenie geological background, geological characteristics of mining area and deposit, deposit genesis are dis- cussed, the results show that：（1）the deposit is occurred in the tectonic melange rock belt of ductile shear ophiolite of the northwestern Jiangxi Province, the basic structural framework of the mining area is formed by the nearly EW-direction distribution Dueun antiformal and NNE-direction steep inclined fracture, and the occurrence of the metallogenic and ore-hosting structure （ Dawuban ductile shear deformation belt） is controlled by the basic structure framework in the mining area;（2）in the process of formation and evolution of the Dawuban ductile shear deformation belt, the tectonite and its proximal surrounding rock are altered in different degree, among them, the alterations closely with gold mineralization are mainly for sericitization, silicification, pyritization, galena mineralization, iron dolomitization, fade, etc. ; （3）the mining area can be divided into two tectonic alteration belts,they are quartz-sericite-pyrite-ferrodolomite （Qtz-Ser-Py-Fer） tectonic alteration belt and chlorite-calcite-sericite （Chl-Cal-Ser） tectonic alteration belt;（4）the deposit with the characteristics of multistage evolution and multi-genesis metallogenic,the metallogenic process of the deposit are volcanic sedimentary, regional metamorphism, dynamic metamorphism and magmatic hy- drothermal superimposed enrichment,the genesis of the deposit is the metamorphic hydrothermal type gold deposit controlled by ductile shear belt. Based on the above analysis results, the prospecting indicators and prospecting potential of the mining area are also analyzed, the results show that ： （1）the deposit tectonic position and its altered tectonite combination,ore-hosting strata and rock combination,surrounding rock al- teration combination closely related to gold mineralization are the favorable prospecting indicators in the mining area;（2）the fault depressed belt formed by the intersection of Ducun antiformal and NNE-direction faults is the prospecting potential area of the ＂Tieluoshan type＂ gold deposit,besides that,the enrichment degree of chloritization is enhanced in the depth of mining area by drilling,the contents of metal sulfides in the strata is increased,which indicated that the metallogenic hydrothermal process will be increased, Cu-Au complex ore-body maybe existed in the more depth of mining area. The above analysis results related to the geological characteristics and prospecting potential of Tieluoshan gold deposit can provide some reference for the further prospecting work of gold deposit and Cu-Au complex deposit in the area.