The Characteristics And Metallogenic Condition F Songjiang Cu-W-Zn PolymetallicDeposit In Heilongjiang Province

Songjiang Cu-W-Zn deposit is located in bin county, Heilongjiang Province,tectonically in Yuquan faulted basin of the southeastern margin of Xiao Xing’anrange-Songnen massif uplift belt which trapped in east of Songnen basin and west ofYichun orogenic belt. This region is an important mineral ore province in China.However, it has convenient transportation and four distinct seasons. It’s suitable tocarry out geological work in Summer and Autumn because of cold and dry weather inwinter that often covered with snow. Besides, it has dense forest cover and excellenteconomic development. The main industry is agriculture and forestry， rich in mineralresources and mining industry is developed.The research mainly works on geological background, geochemistry, physicaland chemical environment and Metallogenic Conditions of Songjiang Cu-W-Znpolymetallic deposit, combined of all aspect of analysis and studies about typicalskarn deposits home and abroad, fingers out genetic types and discusses the origin ofore-forming metals and metallogenic mechanism. Base on all above, comprehensiveregional geophysical and geochemical data in order to evaluate the similarmetallogenic areas’s prospecting surrounding the deposit.Strata exposed in the region consist of Devonian, Permian, Jurassic, lowerPaleogene and wide distributed Quaternary. According to the lithology, formation andgeochemical characteristics analysis, the metallogenetic favorable strata are mainlylower Triassic Jiaojietun group, Tumenling group and middle Jurassic Taiantun group.Technically, the deposit has been found48Cu-Zn ore bodies that No.8orebody is thelargest and followed by No.17orebody,15W ore bodies that are all unexposed andNo.51orebody is the largest,21small.Mo ore bodies that overlapping in W orebodies.Structure in the region mainly formed into series of NE trending structural sytemincluding fold belt, compressive and shear compressive fracture zones during the latePaleozoic Hercynian movements that is squeezed from NW and SE direction. The Songjiang deposit is hosted near the contact zone between granodiorite and Jiaojietungroup and Tumen group wall rock, control by Pinshan-Quanxiao complex anticline.The deposit is mainly divided into Cu-Zn orebody and W-Mo orebody. It’smineralization mainly occurs as Automorphic-hypautomorphic granular texturemetasomatic dissolution texture grid texture and disseminated structure, net veinedstructure, crumb structure and banded structure. Ore mineral assemblage is relativelycomplex, mostly pyrite, bornite, sphalerite, galena, pyrite, magnetite, magnetic pyrite,scheelite, slightly chalcocite, tetrahedrite, molybdenite, marcasite, arsenopyrite,bismuth, copper, lead and so on. Secondary assemblage is malachite, azurite,chalcocite and so on. Gangue assemblage mostly is garnet and diopside, mainly ishedenbergite, wollastonite, tremolite, idocrase, scapolite and actinolite, slightly isbiotite, chlorite, quartz and calcite. Alteration consists of mainly is skarnized,silicification, carbonation, sericitization, feldspathization, chloritization, epidotizationand so on, among which skarnized, silicification, carbonation, sericitization areclosely associated with mineralization.Songjiang deposit has typical characteristics of contact metasomatic genesis,specifically divided into diorite-skarn type deposits. The geochemical analysisindicates that granodiorite is closely related to mineralization, is the origin of heat andprovides mineral resource, and belong to peraluminous calc-alkaline series.Granodiorite, skarn and wall marble has strong comparability in rhondrite-normalizedREE patterns and trace element spider patterns by normalized against primitivemantle, which could be use to analysis the orgin of ore element. The deposit has anobvious mineralizing zonation from Granodiorite to wall rocks. Thechondrite-normalized REE patterns of Granodiorite, skarn and marble show a greatcommparability. However, the W and Mo elements mainly originate from granodiorite,and the Pb elements mainly come from carbonate. While the Cu, Zn elements mayoriginate from both, but the Cu elements tend to come from the latter more, the Znelements tend to come from the former more. This can explain the obviously mineralzonation from the granodiorite to carbonate：Mo-W, Fe-Cu, Cu-Pb-Zn and Pb-Znmineralization in Songjiang polymetallic deposit.Results from geochemical analysis indicate that the deposit formationenvironment is an active continental margin. REE chondrite-normalized distributioncurve is right tilting, implying the strong fracturation of LEE and extremely depletedin HEE. Trace element analysis shows the enrichment large ion lithophile elements (LILE), depleted in Nb、Ta、REE high field strength elements (HFSE), inferring atypical island arc and active continental marginal characteristics.The granodiorite dating results indicates15measuring point of zirconage206Pb/238U age values ranged from178±2-191±2Ma, the206Pb/238U weighted meanage should be184±2Ma(MSWD=6.4), representing the formation age ofgranodiorite.According to the dating results, mineralization and intrusion of thedeposit formed round1.8Ga.Combined with ore-forming geological background, geology and geochemicalcharacteristics, we inferred ore forming process of the Songjiang Cu-W-Znpolymetallic deposit that late Indosinian movement (227-175Ma) in LateTriassic-early Jurassic, the ancient Asia tectonic belt begain to switching Pacifictectonic belt, extension is transferred to extrusion of tectonic environment, the easternPacific plate Jia Musi-Khanka block was subducted and collided in the area to formeda series of structural fracture, which at the same time to erupt lots of intense magmaactivitives and mineralization. The Songjiang Cu-W-Zn polymetallic deposit was theresult and was the specific mineralization model of the tectonic environment situation.Study the specific characteristics, to integrate geophysical with geochemical dataof the deposit, particularly to study on the1:50000area stream sediment surveyresults, we totally mark out8abnormal combinate areas in Songjiang region.Gong-08-Hs-8anomaly was reflected by existing deposit, and Gong-08-Hs-4anomalywas caused by ccurrent ore, and Gong-08-Hs-5, Gong-08-Hs-6, Gong-08-Hs-7maybe the undiscovered orebodies that to prospect in future in this target areas.