Origin And Metallogenic Environment Of Permian Manganese Deposits In Yingpan Township,Nayong County,Guizhou Province

Manganese is a strategic key metal element,which is widely used in metallurgy,new energy batteries and other industries,and has great economic value.In addition,as a redox-sensitive element,manganese is an important material for inverting the evolution of the earth’s ancient oceans and paleoenvironments.It is a typical area of global Permian large-scale sedimentary manganese carbonate deposits in northern Guizhou and eastern Yunnan,and the Shuicheng-Nayong manganese ore area is located at the western edge of the northern Guizhou-eastern Yunnan metallogenic belt,which is different from the mineralization scale,type and mineralization environment of manganese ore in the Zunyi area of the eastern margin.In view of this,this study deeply explores the mineral source,enrichment mechanism and mineralization process of manganese ore in Nayongying through sedimentology,mineralogy,elemental and isotopic geochemistry,identifies the key control factors,and clarifies the relationship between manganese mineralization process and regional tectonic events,paleogeography and paleomarine environment evolution.Based on the above research,this paper obtains the following understanding:Manganese ore is an important strategic and scarce mineral resource in China,which is widely used in metallurgy,new energy batteries and other industries,and has great economic value.Manganese is also a redox-sensitive element,which is an important vehicle for reconstructing the evolutionary history of the earth’s environment.The Permian sedimentary manganese deposits are extremely developed in northern Guizhou and eastern Yunnan,but the manganese deposits developed in Shuicheng-Nayong area,which is located in the western edge of this manganese belt,are obviously different from the Permian manganese deposits developed in Zunyi area in terms of deposit scale and ore type.In view of this,this paper takes the Permian manganese deposits in Yingpan,Nayong as the main object of study.By using sedimentology,mineralogy,elemental geochemistry and other research tools,we deeply investigate the source of manganese ore-forming materials,enrichment mechanism and ore-forming process,and further explain the key ore-control factors,and explore the coupling relationship between manganese ore-forming and regional tectonic events,paleogeography and paleomarine environment evolution.The following insights were mainly obtained:（1）Nayong Yingpan manganese ore is produced at the top of the Middle Permian Maokou Formation,the ore type is mainly manganese oxide,and the ore body is mainly distributed on the surface or near the surface in a laminar or earthy form,and the ore body and manganese-bearing siliceous rocks,manganese-bearing siliceous tuffs and siliceous rocks are often interstratified.（2）The manganese ore develops a large amount of manganese oxides such as soft manganese ore,irregular striped magnetite and a large amount of strawberry-shaped hematite assemblage,and residual pyrite can be seen in the center of individual strawberry-shaped hematite.Combined with the characteristics of V/Cr,Ni/Co and V/（V+Ni）ratios,it reflects that the environmental conditions when the manganese ore was deposited were oxidizing environment.（3）The concentrations of Th/U,Co/Ni,Y/Ho,La/Ce ratio,δ³⁰Si values,and Fe-Mn-Al and Fe-Mn-（Cu+Ni+Co）×10 of manganese ore and ore-bearing siliciclastic rocks indicate that hot-water material was obviously involved in the manganese ore formation process.Combining with the spatial and temporal distribution characteristics of the Middle and Late Permian hot water-forming siliciclastic rocks in South China and the time frame of volcanic activity eruption related to the Emei mantle column for manganese ore formation,it is concluded that the manganese ore-forming material of Nayong Yingpan mainly comes from the early submarine volcanic eruption system of the Emei mantle column.（4）The hydrothermal fluid related to the early Emei mantle column activity brought manganese and iron into the Qianzhong Trench through the co-depositional fracture,and manganese-bearing tuffs were formed in the oxidized water body at the western edge of the Trench because of the different redox water bodies at the eastern and western edges of the Qianzhong Trench.After the late Middle Permian,the rocks of the mineral embryonic layer were gradually exposed to the surface,and the strong epigenetic weathering caused the impurity elements in the manganese-bearing tuffs and manganese-bearing siliceous rocks to be leached out,and the manganese was enriched twice in the process of weathering,and gradually formed the manganese oxide ore layer.A comprehensive study on the sedimentary and tectonic background,geological and geochemical characteristics of Nayong Yingpan manganese ore shows that Nayong Yingpan manganese ore is a manganese cap-type secondary weathering deposit,and its formation goes through two stages:the initial enrichment stage of manganese quality and the epigenetic weathering stage of mineralization.