| After finding dahutang tungsten deposit recent years, zhuxi deposit is a newly ultra large tungsten deposit of megatonnage. The deposit is well known for its deep burial, large scale, thick ore-bodies and multiple types of ore-body. The exploration of the zhuxi tungsten polymentallic deposit breaks the traditional understanding of small scale、discontinuous ore-body and inhomogeneous grade of the skarn type deposit of Taqian-Fuchun Metallogenic Belt in Northeastern Jiangxi. Basing on summarizing previous research results in ditail, using researching methods of modern deposits and applicating modern testing technology, this paper analysised geological background, ore-related igneous rocks, metallogenic materials, ore-forming fluid, ore-controlling factors and prospecting criteria. By buiding ore-forming model and prospecting model, we obtained following mainly understandings:1、There are many stratums related closely with Zhuxi deposit, including metamorphic sandtones and huanglong limestone, dolomitic limestone, dolomite,and marble of in new proterozoic of shuangqiaoshan formation, limestone and marble in Carboniferous of Chuan-shan formation and limestone of qixia formation. The tectonic combination style of Mining Area are as follows: nappe structure and slipping nappe, and Nappe tectonic stress direction from northwest to southeast, and pushover to a high of rock instability due to gravity northwestward reverse sliding cover, and nappe-slip coating layer between the expansion space controlling main ore outputting of bedded and thick-bedded skarn; Nappe- slip and covering-body controls outputting of ZhuXi mining and lenticular skarn body veins by a series of messy secondary fissures. Besides, Nappe and Sliding nappe are rich in siliceous footwall, and aluminum double bridge Mountain Bridge on the disc-rich metamorphic sandstone and calcareous(magnesia) Huanglong formation, Chuanshan formation and other carbonate rocks consistes of "Si/Ca Interface" and plays a more important role to mineral precipitation and enrichment. Emplacement sequence of magma in mining area is Jinningian granodiorite porphyry ' Middle Jurassic minette ' Late Jurassic-Early Cretaceous granite porphyry and biotite granite. Mineralization body includes mainly granite pluton, showing rock and rock veinlike output, and secondary output is granite porphyry in vein, and both of which are concealed rock body. Biotite granites enriched in high field strength elements U, Ta, P, Hf, Y and lithophile element Rb, depleted in high field strength elements Nb, Ti and lithophile elements Ba, K, Sr, and the ratio of Nb / Ta is 1.9 to 4.5. REE(ΣREE) is lower, as 64.64 × 10-6 ~ 85.4 × 10-6, average in 75.58 × 10-6. LREE fractionates strongly, and negative Eu anomaly, distribution patterns as a whole showing a rightist dippers, are aluminum-high-K calc-alkaline series peraluminous S-type granites. For characteristics of altered granite are similar with porphyry alteration, it may be homologous magmatic rocks.2 、 The geological characteristics of the deposit were studied in detail,including:①ZhuXi deposits occur in the overlying Qixia group greisen tungsten ore, The middle layer tectonic belt and skarn tungsten copper(zinc) ore of ontact zone of rock produces quartz in deep concealed altered granite tungsten(copper) ore, and produced in under covering-Shuangqiaoshan formation vein-type mineralization body which was composed of "four in one" type of altered granite-skarn ore. ②Skarn ore mainly shows as dense disseminated, stockwork, smallmassive. Altered granite, greisen and quartz vein type ore’s main structure is based on disseminated veinlets. Ore textures are mainly crystal structure, metasomatic texture and exsolution structure. ③main ore minerals are tungstite, chalcopyrite, sphalerite, pyrrhotite, pyrite, gangue minerals mainly are skarn minerals(including garnet, pyroxene, wollastonite and other minerals) and quartzs along with some anhydrites, calcites and fluorites. ④dividing the Zoning model of metal minerals and ore-forming elements in skarns: from orebody to wall rock the distribution of metal mineral is chalcopyrite ± pyrite ± scheelit ± molybdenite' scheelite ± chalcopyrite ± sphalerite' chalcopyrite ± sphalerite ± galena ± scheelite; the correspondingzoning of ore-forming elements is W ± Cu'W + Cu ± Zn' Cu + Zn ± Pb ± W. ⑤The establishment of the skarn mineral assemblages and compositions of zoning model: Garnet + diopside(Garnet: diopside>4:1) ' diopside+garnet+wollastonite(diopside: Garnet: wollastonite >7:2:1) ' tremolite + diopside + wollastonite(tremolite: diopside: wollastonite >5:2:1). ⑥mineralization is divided into three phase and six stages, the gas water hydrothermal stage includes early skarn stage, late degenerate alteration stage, greisen stage, quartz-tungsten copper zinc phase, quartz- copper lead zinc sulfide stage and calcite tungsten phase and determined the formation sequence of Zhu Xi tungsten copper.3、Determining the metallogenic epoch of deposit by the study of ore deposit geochronology, diagenesis and mineralization age are respectively 146.9±0.97 Ma ~ 152.9±1.7Ma and 144±5Ma, this Shows diagenesis and mineralization of Zhu Xi have the feature of isochronism.4、Revealing the source of ore-forming fluids and substances in Zhu Xi and it is suggested that ore-forming fluid mainly derived from magma,but later there is addition of atmospheric precipitation. Tungsten, copper, zinc and other metal elements were mainly derived from ore rock and there are a few from the surrounding rock. The source of calcium in scheelite Is complex, mainly is from calcites of Huanglong and Chuanshan group carbonates, some calcium comes from plagioclase, garnet, fluorite and other calcium containing minerals. The source of the different types of orebody in scheelite calcium is slightly different, calcium in skarn scheelite orebody mainly originates from calcites in the surrounding rocks, calcium of the altered granite type, scheelite greisen tungsten ore, quartz vein type orebody mainly originates from the plagioclase sericite of metallogenic rock.5、Established theprospecting model according to the”multinity metallogenic model” in Zhu Xi deposit.6、Discussed the southern Jiangxi tungsten North expansion mechanism, it is suggested that there is ore source layer which is rich tungsten in Gannan and Ganbei geological body. Tectonic magmatite that caused by the conversion of Tethys to the ancient Pacific tectonic domain May be the main cause of expansion of tungsten from South to North in Jiangxi. Deposits in Gannan mainly are quartz vein type and altered granite type wolframite deposits, while deposits in the northern area of Jiangxi are porphyry- skarn type scheelite deposits. The difference may be related to the content of silicon, calcium and aluminum in ore formation between Gannan and Ganbei. |
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