Stratigraphic Determination And Ore Bearing Analysis Of Carboniferous And Permian In Yamansu Area,Eastern Tianshan

The Yamansu area is located in the middle of the Jueluotage structural belt in the Eastern Tianshan Mountains.It is a key part of the late Paleozoic oceanic-continental transition in the Paleo-Asian Ocean.It widely exposes the Carboniferous and Permian volcanic and clastic sedimentary rock formations.To clarify the sedimentary sequence of the Late Paleozoic strata in the region,and to provide basic geological data for further exploration of the tectonic evolution of the Paleo-Asian Ocean and to evaluate the potential of stratigraphic mineral resources in the region.In this study,a total of five groups of strata mainly in the Carboniferous and Permian in the Yamansu area are studied(including the Lower Carboniferous Aqishan Formation,the Lower Carboniferous Yamansu Formation,the Upper Carboniferous Wutongwozi Formation,and Middle 2 Permian Aqikebulake Formation,Middle Permian Albasayi Formation),We carried out detailed field geological surveys and used petrology,isotope geochronology and paleobiology stratigraphy as the main theories,and systematically sort out and determine the above strata;On this basis,a large number of geochemical samples were collected,and the evaluation of formation mineralization was carried out using evaluation factors such as ore-forming element enrichment coefficient,poststacking strength,and ore-forming element variation coefficient,and related evaluation theories and methods.The metallogenic potential of the strata in Yamansu area was comprehensively evaluated.The results and understanding of this article are as follows:(1)In terms of stratigraphic determination,the five groups of strata have been reorganized,and the basic stratigraphic framework has been initially established from the time: the Aqishan Formation and Yamansu Formation,which were originally assigned to the Tugubulake Formation,are redefined.The formation ages of the two groups of strata are mid-Early Carboniferous and mid-late-Early Carboniferous;the formation age of the Wutongwozi Formation is limited to the early Late Carboniferous,and the original Kulai Formation in the area is disintegrated into the Akizbulake Formation and The formation of the Albabasayi Formation is defined from the early Permian to the Middle Permian.(2)In terms of lithology,rock assemblage and tectonic background,the following knowledge is obtained: the lower Carboniferous Aqishan Formation is constructed as a set of marine volcanic rocks,and the formation environment is a subducted volcanic island arc;the lower Carboniferous Yamansu The group is a combination of deep-sea volcanic clastic rocks and normal sedimentary rocks,which is carbonate platform deposits,and the formation environment is the subduction-reduced island arc;the Upper Carboniferous Wutongwozi Formation is a set of structural mixed rocks composed of matrix and blocks The composition of the body,where the matrix lithology is a set of deep-semi-deep sea clastic rock deposits,and the block lithology is mainly a rock combination formed in the oceanic environment such as diabase,basalt and radiolarian siliceous rock;Middle Permian The Aqikebulake Formation rock assemblage is a set of terrestrial detrital sediments from land marginal to shallow marine facies,formed during the collision orogeny;the Middle Permian Albabasayi Formation is a set of basic volcanic assemblages formed in Stretch fault basin.(3)In the analysis of strata mineralization: the results of the enrichment factor(K)analysis of ore-forming elements show that,in addition to the relative enrichment of some elements in the Aqishan and Albasayi formations,the other strata in the various layers in the Yamansu area Most of the elements are relatively depleted,which is lower than the background value of the East Tianshan;the analysis results of the superposition intensity(D)and the variation coefficient(Cv)of the ore-forming elements in the later period show that Au,Sb,Bi,Ni and other elements are in various layers.The late-stage superposition effect is the strongest,and its composition change index is the highest.(4)In terms of metallogenic potential evaluation: combined with the metallogenic favorable coefficient(Ma),a comprehensive evaluation of the metallogenic ability of the late Paleozoic strata in Yamansu area.Relative depletion of elements in the formation of Yamansu,Wutongwozi and Aqikebulake;There are many optimal oreforming elements in Aqishan formation and Albasayi formation,which are the main ore bearing horizons,among which the dominant ore types are Cr,Zn,Ag,Co and Cr,Ni,Cu,Co respectively;only Ag element in the Middle Permian Aqikbulak formation has a certain ore-forming prospect.