Research On The Relationship Between Tectonic Deformation And Controlling Ore Of Dashui Manganese Ore Belt In Tashui Area,Beshan,Gansu

The Tashui region is located on the northern edge of the Beishan Rift System and due to the control of the fault structures of the Hongliuhe and Xingxingxia,its structural deformation is complex.Meanwhile,the study area is also a potential area for manganese ore.The study of tectonic deformation in the Tashui area is of practical significance for clarifying the ore-controlling geological conditions of the Dashui Mn mine and guiding the prospecting of the area.In this paper,by means of the field geological investigation of geometry,kinematics and their cut-off relationships,the Tashui region is divided into several deformation sequences.The geochemical characteristics of the manganese ore surrounding rocks and ores are analyzed and the relationship between structural deformation and manganese ore-controlling The following understanding and conclusions has been reached:1.There are four stages in the tectonic deformation in the study area:the first stage is the tight syncline fold and sloping NNE where the Axis tracks is inclined;the second stage is the oblique and sloping NNW where the Axis tracks is inclined,and the inclined and inclined vertical fold is inclined toward the NEE,and the two are Span Overlay.According to the age of the tower water intrusion in the folded strata,is383-412 Ma,it can be inferred that the two-stage fold occurred before the Early Devonian;the third stage is the NEE left-lateral strike-slip fault,mainly affected by the Hongliuhe fault.The effect of left-lateral strike-slip shear deformation may be that the deformation time may be early Mesozoic;the fourth phase is a conjugate brittle fault that goes toward NE-SW and NW-SE,and the age of deformation is the Cenozoic.2.The manganese-bearing strata of the three Manganese ore sites in Dashui manganese ore zone,Huaping,Dashui and Tashui are mainly Upper Sinian.The manganese ore in this zone is mainly colloidal-bonded manganese ore.Ore mineral for hard manganese ore,and the chemical formula is MnO₂.The surrounding rocks are dominated by clay rocks and limestones,along with a small number of siliceous rocks.Accouding to the analysis of the geochemical characteristics of ore and surrounding rock,it can be manganese ore and surrounding rocks are exposed to hot water.Therefore,light rare earths were significantly enriched with heavy rare earths,trace elements Ni/Co is mainly 0.19-2.25,with an average of 1.30;V/?V+Ni?is mainly0.01-0.96,with an average of 0.31.Overall,manganese ore is in the oxygen-rich environment.3.The fourth stage deformation in the Tashui area affected the ore-forming mineralization.The superimposed folds in the first two stages changed the spatial distribution of the manganese-containing layer,making it thickened at the turning end.The left-lateral strike-slip fault in the third stage and conjugate brittle fault in the fourth-phase provide a channel for the leaching and enrichment of manganese ore.4.Propose the next step of prospecting,and the key investigation area should be in the western part of the study area to find the places where the ore-bearing strata are transformed by brittle faults.This area is abundant in the manganese ore.