青海尕龙格玛铜多金属矿床矿物学特征对成因的指示意义

The mineralogy feature and its significance for deposit genesis of Galonggema Cu-polymetallic deposit in Qinghai Province

为了探究尕龙格玛铜多金属矿床成因,选取金属硫化物为研究对象,通过电子探针进行矿物学分析研究。结合矿床地质特征,为该矿床成因提供依据。结果表明:该矿床成矿阶段可划分为火山沉积热液期和中温热液硫化物期,并进一步细分为热水沉积-黄铁矿阶段、石英-黄铁矿阶段、碳酸盐阶段、铜铅锌-硫化物阶段和闪锌矿-碳酸盐阶段等五阶段。不同成矿阶段的黄铁矿标型特征表明其分别具有火山喷流沉积、火山热液改造和岩浆热液等不同成因。该矿床经历了早期火山喷流沉积,形成火山沉积(热液)矿化;中期受较大范围的火山热液充填交代;后期中酸性岩浆侵入引起的中温岩浆热液矿化,沿着断裂构造上侵,在前期矿化体中叠加成矿。

In order to explore the genesis of Galonggema Cu-polymetallic deposit,metallic sulfide is selected as the research object and mineralogical analysis is carried out by electron probe method.Combined with geological characteristics,it provides the basis for deposit genesis.The results show that the metallogenic period of the deposit can be divided into volcanic sedimentary hydrothermal stage and middle temperature hydrothermal sulfide stage.It can be subdivided into to five phases,hydrothermal sedimentary-pyrite phase,quartz-pyrite phase and carbonate phase,Cu-Pb-Zn sulfide phase and sphalerite-carbonate phase.The typomorphic characteristics of pyrite in different ore-forming phases indicate that the pyrite has different genesis,volcanic sedimentary-exhalative type,volcanic hydrothermal alteration type and magmatic hydrothermal type.The deposit is experienced by early volcanic exhalation sedimentary process and volcanic deposition(hydrothermal)mineralization is formed.In the middle phase,it is filled and metasomatized by a wide range of volcanic hydrothermal fluids.In the later phase,the intermediate temperature magmatic hydrothermal mineralization caused by intermediate-acid magmatic intrusion,is superimposed and hosted in the early mineralization bodies along the fault structure.