The Study Of Geology, Geochemistry And Metallogenic Model In Luming Molybdenum Deposit, Heilongjiang Province

Luming molybdenum deposit is located in the north of Tie Li, HeilongjiangProvince. Considered with geotectonic view, it is located in the east section ofxing’anling-mongolian orogenic belt, the northern-central of Lesser Xing’an Range. Itis a newly discovered tipical large-sized porphyry molybdenum deposit.The strata exposed in the region mainly include Qianshan Group and XiaojingouGroup of Proterozoic, the Mesozoic Jurassic MaoEr mountain group of quaternarysystem as well as the new generation; Widely in the mine development phaseindosinian and yanshanian granite; fault structure are composed entirely of NNE toBeiguan–Pingan–Luming–Yilin Compression shear fracture and NNE, NNE, NEEsecondary fracture structure, etc.Lrregular shaped ore bodies and lenticular output, The main metal mineral in theore for molybdenite、 pyrite and chalcopyrite, etc. The secondary mineral ofpyrrhotite sphalerite galena and magnetite; gangue mineral are quartz, plagioclase,alkali, feldspar, chlorite, biotite etc; wall rock alteration includes silicification,potassic alteration, feldspathization, lithification sericitization biotite and kaolin, etc.The types of fluid inclusions of mainly for gas-liquid two-phase inclusion, crystalmineral inclusion and gas phase inclusion, most of them are two-phase isolatedprimary inclusions. The temperature of fluid inclusions ranges from110℃to472℃,the mainvalue is between230℃and320℃; the salinity ranges from1.56wt%NaClto37.58wt%NaCl; the value of density is between0.39and1.00g/cm3. The value ofpressure ranges from8.30MPa to45.93MPa. Laser Raman Spectroscopy analysis ofthe fluid inclusions reveals their predominant CO2and CH4, followed by H2Sconstitute. Metallogenic process have experienced four mineralization stages fromearly to late:(Ⅰ) the pyrite-quartz stage;(Ⅱ) the quartz-molybdenite stage;(Ⅲ) thechlorite-molybdenite-quartz stage; and (Ⅳ) the quartz-carbonate stage. Thecorresponding uniform temperature is410～475℃、320～400℃、220～320℃、110～210℃， Metallogenic temperature decreases gradually, Ⅱstage，the fluid salinity isdivided into two groups:4.17～8.81%NaCleq and31.48～37.58%NaCleq; Ⅱstage， the fluid salinity is divided into two groups:2.56～8.40%NaCleq and2.89-8.94%NaCleq. Ore-forming fluid system from the early stage H2O-CO2-NaCl system withhing temperatures, hing salinities fluids types to the late stage H2O-NaCl system withlow temperatures, low salinities fluids types. Combined with characteristics of fluidinclusions and paragenesis of mineral assemblages, it is suggested that fluid boilingand CO2escaping were the leading factor for the formation of the deposit.The main metallogenic stage ore-forming fluid has the characteristics ofmagmatic water and meteoric water mix. Ore-forming materials are derived fromcrust-mantle mixed source and mainly from crustal source.The molybdenite Re-Os model age is180.2~185.9Ma and weighted average ageis（183.4±2.2）Ma, it indicates that the Luming molybdenum formed in the EarlyJurassic, and the metallogenetic age is the same as or slightly later than diagenetic age.Mechanism for the formation of ore deposits in the region more plate split and Eurasiais closely related to the subduction of the Pacific plate in the middle.Mineralization associated with intrusive rocks are peraluminous–metaluminous,high-K calc-alkaline series, a small amount of shoshonitic series, which has similarto subduction zone magmatism geochemical characteristics and impliesmineralization Pacific subduction process, and formed continent-continent collision inmaking the transition back tectonic regime transition period.