Alteration And Trace Element Characteristics Of Copper Porphyry Copper Deposit, Dexing, Jiangxi Province

Dexing porphyry copper deposit is the largest open pit mining in Asia, Tongchang mining area is the largest mining area in Dexing porphyry copper deposit.Study area is located in the joint part of eastern Yangtze plate, Jiangnan anteclise and Gan-hang fracture. Sinian Shuangqiaoshan group is the most widely developed, the ore field is mainly exist Jiudu group, magmatic activity is strong in the area, related to mineralization is mainly Yanshanian granodioritic porphyry, quartz diorite porphyrite.Orebody mainly existed rock mass and surrounding rock contact zone of strong alteration zone, in which the occurrence of surrounding rock is 2/3. The main ore minerals are metal sulfides, such as pyrite, metal sulfide, chalcopyrite, molybdenite, tennantite, bornite etc. The gangue minerals include quartz, silicates, carbonates, sulfates, epidote, feldspar etc.Mining area strongly altered, combined with field observation, thin section identification, PIMA application, the mining area is divided into six alteration belts: rock mass is divided into three belts, potassium feldspar-illite belt, chlorite-sericitization belt, quartz-sericitization belt, surrounding rock is divided into three belts: quartz sericitization belt, chlorite sericitization belt, chlorite and illite petrochemical belt.PIMA data plane model, combined with the content of trace elements in rocks shows that in the areo that the reflectivity and strength ratio are large but content of Cu is relatively low, reflectivity and strength ratio are relatively small but content of Cu is relatively high. Regional average element content inversely are proportional to reflectance, strength ratio.The R cluster analysis of trace elements find that the ore-forming elements are Au-Ag Pb-Bi-Cd-Sb-Zn-Cu, and the main metallogenic factors are Cu-Au by R factor analysis. In Each alteration belt rare earth elements(REE) patterns are LREE-rich. The change of the contents of rare earth element in the alteration zone is great. Taking hydrothermal as the connecting point, the rock mass and the surrounding rock as a unified system, in the alteration mineralization process, the rock mass rock REE has the complementarity. The total REE average content along with the enhancement of Cu mineralization, content also increased, and positively correlated with Cu mineralization.In the Tongchang mine of Dexing copper mine, except the main ore-forming elements Cu and Mo, the elements of Co, Re, Ag, Au and other elements also have very large economic value.Au, Ag mainly as independent minerals output, natural gold accounted for more than 90%; Re occurs mainly in molybdenite; Co occurs mainly in pyrite.The distribution of Au, Ag, Re and Co is uneven, but it has certain symmetry.. The distribution of Au is not particularly large with alteration of strength, rock to out rock average content of Ag decreased gradually; Co in the altered variable weak chlorite-sericitization belt content is higher, the content of other belts are low; The average content of Au, Re, Mo, Cu are high in the contact zone of the main rock of the surrounding rock, and alteration in these areas is strong. Au, Ag, Re and Co are sulphophile elements, and can be migrated in the hydrothermal solution by the complexing ion, when the hydrothermal physical and chemical conditions are changed, Au, Ag, Re and Co will be enrichment and precipitation.