Metallogeny Of The Graphite Deposits In The Eastern Junggar Area,Northern Xinjiang

In recent years,great breakthrough has been made in the prospecting of crystalline graphite in Eastern Junggar,Xinjiang,which shows good metallogenic potential of crystalline graphite.However,due to later found time,graphite deposit studies overall remain in the low degree and the current research work is limited to a single deposit without the systemic research of graphite deposit in Eastern Junggar.This situation not only restricts the understanding of graphite genesis and metallogenic regularities in Eastern Junggar,but also directly affects the extensive crystalline graphite ore-prospecting work in the next exploration deployment,large graphite resources base construction.This thesis selected typical graphite deposits in Eastern Junggar applying methods of mineralogy,petrology,mineral deposit,isotopic geochronology,geochemistry,carbon isotope.This study focus on analysis of graphite deposits'geological characteristics,ages of diagenesis and mineralize,sedimentary environments of deposits,carbon source,and ore-controlling factors.Based on these studies,this thesis further summarizes graphite deposit type,mineral deposit genesis and metallogenic regularities in Eastern Junggar.The graphite deposits discovered in Eastern Junggar are produced in the secondary fault fold belt of regional major faults.Their spatially distribution are controlled by three structural magmatic belts with NW-SE trending such as Erqis-Mayinebo belt.Four graphite ore bodies including Kongkere,Dabuxun,Sandeke,and Tuerkuli are controlled by brittle-ductile shear zone and ore bodies experienced plastic deformation.The mineral alterations are mainly sericitization,kaolinization,and ferritization.The graphite is fine scales to microscopic flaky texture.Its diameter is between 0.001 and 0.2 mm and fixed carbon content is between 11.56 and 15.6%.The graphite orebody of Huangyangshan occurs in alkaline granite,the mineral alterations include dystallization,silication,and biotitization.The fixed carbon content is 6.15%,and the crystal scales and leaf structures are in the range of 0.05?0.2mm with the maximum of 0.5mm.Zircon U-Pb chronology and geochemical analysis have been conducted in typical graphite deposites.Sedimentary ages of four graphite mine systems including Kongkere,Dabuxun,Sandeke,and Tuerkuli systems are between Tournaisian(Early Carboniferous)to Bashkirian(Late carboniferous,336?321 Ma).These ore bearing series belong to the Lower Carboniferous Jiangbasitao Formation and the Upper Carboniferous Batamayineishan Formation.The original rock are graywacke or feldspar sandstone and the source areas are composed of felsic rocks with a complicated tectonic setting.The metallogenic age of typical graphite deposits in Eastern Junggar is concentrated in the late Late Carboniferous(301?312Ma).Based on the carbon isotope,X-ray,Laser Raman Spectroscopy and fluid inclusions of typical graphite deposits,the average value of carbon isotope?¹³C in Kongkere and Tuerkulu graphite deposits is-21.4‰and the average value of carbon isotope?¹³C in Huangyangshan and Sujiquan graphite deposits is-20.4‰.The consistency of graphite carbon isotope?¹³C in typical graphite deposits in the Eastern Junggar not only reflects that the carbon source of deposits is organic origin,but also suggests that graphite protoliths were formed in similar sedimentary environment.The typical graphite deposits have similar XRD patterns with sharp peaks,and the d₍₀₀₂₎of graphite ranges from 3.353 to3.356?,indicating that the graphite mineral order is fine.The Laser Raman Spectra of Huangyangshan graphite mine show sharp G band and weak D1 and D2 defect peaks,indicating high crystallinity of graphite.The R2 value of the graphite crystals ranged from0.02 to 0.14 and the corresponding formation temperature was 578 to 632?.The graphite deposits in Eastern Junggar can be divided into three types of mineralization including the first related to the alteration of kali-feldspar granite,the second related to post-magmatic gasification hydrothermal,and the third related to carbonaceous slate and carbonaceous siliceous slate.Accordingly,two genetic types of graphite deposits are proposed in Eastern Junggar.They are tectono-magmatic thermal metamorphism type and magmatic gas-liquid alteration type,which are different from the previous classification,and are conducive to guiding regional prospecting.Depending on the metallogenic geological background,the main ore-controlling factors,genetic types and temporal and spatial distribution of the discoverd typical graphite deposits.Favorable zone of graphite mineralization in Eastern Junggar can be divided into three metallogenic subzone:Erqis-Mayinebo graphite ore-forming subzone(?-1),Zhagahe-Aermantai subzone(?-2),and Kalamaili-Moqinwula subzone(?-3).These results can provides the basis for the next step of graphite ore exploration deployment in the Eastern Junggar,Xinjiang.