The Alteration Characteristics And Mineralization In Dongguashan Copper-gold Deposit And Hucun Copper-molybdenum Deposit Of Tongling, Anhui Province

Dongguashan Copper-gold deposit and Hucun Copper-molybdenum depositare important deposits in Shizishan copper-polymetallic ore-field of Tonglingregion, Anhui Province. Based on the general understanding of the regionalgeological background and geological features of Tongling Shizishan ore field, thegeological features, alteration and mineralization of Dongguashan Copper-golddeposit and Hucun Copper-molybdenum deposit were researched. The alterationtype, alteration zoning and mineral assemblages of intrusions and wall-rock wereconfirmed. Combing with previous achievements of other scholars, themineralization and genesis of Dongguashan and Hucun deposits were discussed.According to privous materials, the ore bodies of Dongguashan Copper-golddeposit and Hucun copper-molybdenum deposit both have two parts. The upperpart is skarn type, and the deeper part is porphyry type. The alteration zone ofDongguashan deep deposit is regularly potassic alteration (K-feldspation,silicification)â†'phyllic alteration (sericitization, silicification)â†'skarn alterationâ†'hornfelsing and marmarosis alteration from the ore body center to the wall-rock.Although Hucun deeper deposit developed porphyry type alteration, its alterationzone isn’t obvious. Compared with the major porphyry deposits of the world,Intense K-feldspar alteration pervaded the Donggaushan deposit, but intense biotitealteration pervaded the other world-class porphyry deposit. Propylitic zone was notdisplayed in Dongguashan peripheral, and the argillic was not enough to make a zone,.There are three types of alteration in Dongguashan deeper ore body: potassiumsilicate alteration, quartz-sericite alteration and skarn alteration. Potassium silicatealteration affected the near site of rock center with strong K-feldspation andsilicification. Quartz-sericition alteration overprinted the potassium silicatealteration, and their mineral assemblages were mianly quartz, sericite and pyrite.Skarnization alteration developed in the sedimentary strata, rock and wall-rock contact belt, the mineral assemblage gives priority to garnet, diopside, calcite orolivine, serpentine, plagioclase humite and chlorite. Compared with typicalporphyry deposits, Dongguashan and Hucun deposits’ alteration zone is relativelyincomplete and unobvious, their deeper ore body were disseminated, veinletdisseminated or stockwork output. The fluid inclusion, trace elements and isotopegeochemistry also indicated that mineralization was closely related to Yanshanianintrusions. Therefore, Dongguashan Copper-gold deposit and HucunCopper-molybdenum deposit both are skarn-porphyry deposits.