Petrological Characteristics And Metallogenic Prospect Of The Bulunkuole Group In Taxian,Xinjiang

Bulunkuole group distributed in Taxkorgan block which is located in the east of the Karakorum orogenic belt and it is the main rock series.Both sides respectively were Kangxiwa fracture zone and Taaxi fracture zone.Bulunkuole group distributed in the both sides of Yarkant River that is affected by the translational fracture of Taxkorgan,it is presenting a strip shape in general and spreading in NW-NNW direction,the metamorphic rock series which is rich in garnet and sillimanite are affected by middle-deep regional metamorphism overall.Based on filed geological survey,the measure of the stratigraphic section,the identification under rock microscope,the analysis of lithogeochemistry and zircon dating data etc,Bulunkuole group was analysed by the petrological feature and metallogenic prospect,also carried out protolith recovery:According to the field measured section and the identification under rock microscope,it is confirmed that Bulunkuole group?Pt₁B?can be divided into A B C three petrofabrics.The lithology of petrofabric A is mainly of quartz schist,pyroxene plagioclase granulite,amphibolite plagioclase gneiss,granite pegmatite etc,the lithology of petrofabric B is mainly of plagiogneiss,oblique amphibolite schist and quartz schist etc,the lithology of petrofabric C is mainly of plagioclase amphibole schist,hornblende schist,quartz schist,quartzite,scapolite diopside marble,granodiorite etc.Bulunkuole group is characteristic with fault and fold development.The faults are more than the fracture,and the tectonic direction is consistent with the regional tectonic line.The formation element deformation is very strong,and the whole structure form and lattice frame are difficult to recover.From now on,three period deformation can be identified.The first stage deformation is the penetrating micro-principle formed in the deep tectonic level shear rheology;the second phase of deformation is the closed and oblique folds formed by MIT?S₁?in the deep tectonic shear rheological environment;and the deformation of the third stage is the distribution of the strong deformation zone and the weakly deformed field.According to the geochemical analysis of the major element,microelement and rare earth element,there is a large amount of terrigenous debris involved in the formation of the rock in the group of Bulunkuole,whose formation environment is similar with the active continental fringe environment.Combined with rock assemblage and deformation characteristics,the original rock is restored to a set of normal sedimentary clastic rocks with a small amount of carbonate rock and basic volcanic rock.The iron ore body which is hosted in the group of Bulunkuole is mainly characteristic by sedimentary metamorphic iron ore.The ore body is layered distribution,and the occurrence is consistent with the surrounding rock,showing a gradual transition.In addition,the lithology ore-controlling characteristic is very obvious,the original sedimentary bedding of the ore-bearing system is clear,and has obvious sedimentary rhythm.Furthermore,its metallogenic materials mainly originate from the marine iron volcanic magma eruption.The result of geochemical and remote sensing anomalies shows that the iron elements of Bulunkuole group?Pt₁B?is abnormal outstanding,and the gravity and aeromagnetic characteristics indicate the strong magnetism of the Bulunkuole group,and it has a great significance to the prospecting of iron ores.Therefore,it has a good prospect for searching sedimentary metamorphic iron deposit in Bulunkuole group.