The Ore-controlling Conditions And Geological Features Of The W-Cu Polymetallic Ore Deposit In The Zhuxi Area Of Jingdezhen, Jiangxi Province

The Zhuxi tungsten-copper polymetallic deposit, found in Northern Jiangxi in recent years, is a perspective super large-scale deposit. Compared with the significant breakthroughs in ore-finding, the theoretical study of this deposit is somewhat poor, particularly comprehensive research on ore-controlling condition.The Zhuxi tungsten-copper polymetallic deposit is located in the eastern part of Jiangnan Neoproterozoic orogen and lies to north of the suture zone between Yangtze and Cathaysian blocks. In the Late Paleozoic, this region was a neritic facies carbonate basin and belongs to Leping-Wuyuan polymetallic metallogenic prospecting area of the eastern Pingxiang-Liping metallogenic zone. The Zhuxi ore-deposit experienced multiply reworking by tectonic-magmatic events from Neopaleozoic to late Mesozoic, and shows favorable metallogenic condition. This paper,we have systematically established the geotectonic framework, stratigraphic sequence, spatial-temporal distribution of magmatic rocks and tectonic deformation features. Futhermore, the geometric characteristics, lithofacies-paleogeographical features and the relationship between tectonic evolution and metallogenesis have also been systematically analysed.Researches including petrography, geochemistry, LA-ICP-MS zircon U-Pb dating and in situ zircon Hf isotope analysis have been carried out on magmatic rocks from Zhuxi area. The research results indicate that granites in Zhuxi ore district mainly consist of granitoid, also smaller amounts of intermediate rock (monzonite) and basic rock (lamprophyre). The A/CNK values of granite and granodiorite are larger than 1.1, therefore they belong to strongly peraluminous type, and synchronously suggest a crustal partial melting source. The A/CNK values of monzonites are within 0.61-0.77, suggesting an igneous source with mantle materials input. The altered granite and granite-porphyry are enriched in Si and K, with their A/CNK values between 1.1 to 1.4, therefore they belong to peraluminous granite. However, the rare earth elements are characterized by the total content is relatively low (REE= 17-20 ppm), with a slightly right-dipping REE pattern but marked negative Eu anomalies. The (La/Yb)n=1.7?2.54, Nb/Ta=1.54-1.78, Zr/Hf=13.4?16.8, and Th/U=0.018?0.024 suggest that these granite and granite-porphyry are sourced form partial melting of crustal materials and suffered strong metasomatism by carbonate fluid. Furthermore, The trace elements are characterized by enrichment of Rb, U, T, Pb and Hf, as well as depletion of Ba, Ce, Sr, La and Ti reveals that these granite and granite-porphyry are originated from a syn-collision setting. U-Pb dating of zircons from the fine-grained granite and granite-porphyry yields two late Jurassic ages which are 151.5±3 Ma and 148.4±3.4 Ma, respectively. In situ Hf isotopic analysis results indicate that the granitic magma was not contaminated by mantle-derived materials, but was basically sourced from the partial melting of the Paleoproterozoic continental crust.This study provides a systematic discussion on the ore-controlling condition from ore source bed, tectonics, magmation and so on. We also preliminary summarize the metallogenic mechanism of this ore deposit. Based on the analysis of the metallogenic geological setting, geological characteristics of ore deposit and the ore-controlling condition, this study briefly summarize the features of ore-forming-related strata, tectonics, magmatite, alteration and so on, concluding the Zhuxi ore deposit exhibits a typical metallogenic model:the upper part of it is mainly hydrothermal vein type ore bodies; the moderate-deep part of it exhibits skarn type ore bodies; and the deeper part of it is granite-porphyry (or altered granite) ore bodies. In addition, the mineralization shows obvious distribution gradation both in horizontal and vertical direction:from northeast to southwest (horizontal derection) as well as from shallow to deep (vertical direction) there appear a Cu?Cu-W?W-Cu mineralization trend, and points out that the study area has the potential to find skarn type and porphyre type copper-tungsten polymetallic ore deposit. Within the scope of the mining area, both following the deep part or SW side to find tungsten polymetallic ore and following the NE side to find copper polymetallic ore exhibit fine prospect.