A Study On Geology,geochemistry Feature And Genesis Of The Buqiong Iron (Copper) Deposit In Tiekelike Metallogenic Belt,West Kunlun

Tiekelike metallogenic belt locates in the continental marginal uplift area of the southwestern Tarim Basin in west Kunlun,xinjiang province.Buqiong iron(copper)deposit is the most representative and only forming metal deposit in the belt,but related researches are very weak.Based on the results of the relevant research data,we have combined the field geological survey and the indoor analysis in order to managing a comprehensive and anatomical study in Buqiong iron(copper)deposit,the study contains the aspects of geology,petrography,petrology,geochemistry,chronology and so on.The thesis has proposed several points as follows.(1)The ore-bearing strata is Kalakashi group of Paleoproterozoic,and its rock types are marble,hornblende schist,biotite schist,garnet-actinolite hornblende gneiss and magnetite-quartz.The protoliths were recovered from the hornblende schist and biotite schist.The result is that the ore-bearing surrounding rock of the Buqiong iron deposit is a medium-basic volcanic rock transition from the Andesite to the Basalt.(2)The strong deformation and degenerative metamorphism belt of the strata are linearly distributed on the mid-deep level regional metamorphic rocks.The transition of the deformation from center to the surrounding of the belt is from toughness deformation to brittle deformation.Degenerative metamorphism rock of chlorite schist is also developed.(3)Iron ore body shape was layered,like lamellar or lenticular,and it contacts with the monoclinic strata of surrounding rock conformably.The main types of iron ore are striped ore and disseminated ore.Granular crystal structure and metasomatic structure are developed.The ore minerals mainly are magnetite and chalcopyrite,and the gangue minerals mainly are quartz,hornblende,garnet actinolite,and so on.Copper mineralization has a close tie with quartz-calcite-sulfide veins,mineralization types mainly are brass mineralization,malachite mineralization and chessylite mineralization;wall rock alteration mainly are silicification,calcitization,martite,chlorite,pyrite mineralization,galena mineralization,etc.the metallogenic period can be divided into sedimentary period,metamorphic period,tectonic-hydrothermal period and epigenetic period.(4)Wall rocks are rich in silicon and aluminum,poor in calcium,the content of high field strength element is high,stripe ore and hornblende wall rock have a similar pattern in rare earth element,the fractionation of light and heavy rare earth element is not obvious,and they have a consistent source.the mineralization material may come from the high temperature hydrotherm of seabed and seawater.The biotite schist of wall rock is similar to the disseminated ores in distribution pattern of rare earth element,which is rich in LREE and deficit in HREE,and it may be the result of post-tectonic-hydrothermal effect.(5)The iron ore body is assumed to be formed in 2000-2350 Ma,and the tectonic-hydrothermal event age after the formation of the rock is 749-764 Ma by dating the zircon from amphibolites of wall rock using LA U-Pb method.(6)Based on the geochemical trace study of the surrounding rock and the previous understanding of the tectonic evolution of Tiekelike area.It can be proposed that the structural background of Buqiong BIF is back-arc basin controlled by volcanic mechanism,and the copper mineralization is closely related to the continental break up of west Kunlun in Neoproterozoic.The metallogenic model can be divided into sedimentary stage(formation of BIF),metamorphic stage(formation of sedimentary-metamorphic iron ore),tectonic-hydrothermal stage(superposition of copper mineralization).