Geological Characteristics And Genesis Analysis Of Fushe Manganese Deposit In Tiandeng,guangxi

The Fushe manganese deposit is located in southwest Guangxi Province,an important manganese ore producing area in China of important prospect of manganese ore mineralization.As a newly discovered manganese deposit,the predecessors still lacked research on manganese deposits in the mining area.This paper mainly focus on the geological characteristics,metallogenic settings and mineralogical characteristics,etc.,combined with geochemical analysis,trying to understand the genesis of Fushe manganese deposit.The Tiandeng Fushe manganese deposit mainly exists in Wuzhishan Formation,Upper Devonian.The main manganese ore bodies are distributed in the silicalite,argillaceous silicalite,mudstone and siltstone of the first and third section of Wuzhishan Formation of manganese-bearing.The manganese ore layer is strictly controlled by the Wuzhishan Formation?D₃w?position and also controlled by the fold structure,and is mostly produced in layers with silicalite,mudstone and siltstone.The natural ore type is manganese oxide ore,with mainly microaphanitic stucture,microcrystalline structure and metasomatic structure,followed by residual crystalloblastic structure,colloid or residual colloidal structure,with blocky,earthy,honeycomb and bean-like shapes,followed by strips and geode-like shapes.The ore minerals mainly include pyrolusite,psilomelane,cryptomelane and romanechite.The gangue minerals are mainly chalcedony,quartz,calcite and clay minerals.The analysis of main trace rare earth elements in manganese oxide ore and its country rock samples from the Fushe manganese deposit show that the lithophile elements of large ions such as Rb,Ba,Th,Ce and Sm are relatively enriched,while K,Sr,Ta,P and Ti are relatively depleted.Ratios of Ti/V,Co/Ni,Ba/Sr,?Fe+Mn?/Ti,Al/?A1+Fe+Mn?,MnO/TiO₂,MnO/Al₂O₃ in ore-bearing country rocks and manganese ore as well as the positive anomaly of rare earth elements Eu all imply the characteristics of hot water precipitation.The Fe/Ti-Al/?Al+Fe+Mn?and logU-logTh diagrams also reflect the enrichment of manganese ore is mostly due to hot water.Participation is closely related.The ratios of U/Th,Ni/Co,V/?V+Ni?and Ni/Co-U/Th in the mining area indicate that the ore-forming sedimentary environment is from anoxic transformed into oxidizing environment.The Fe₂O₃/TiO₂-Al₂O₃/?Al₂O₃+Fe₂O₃?,Fe₂O₃/?100-SiO₂?-Al₂O₃/?100-SiO₂?diagrams of the ore-bearing country rock and manganese ore show the passive continental margin background of the manganese-bearing rock series.Combined with the regional tectonic evolution and lithofacies palaeogeographic characteristics of the Fushe manganese deposit,it is speculated that the sedimentary manganese deposits in the Wuzhishan Formation of late Devonian were distribute equally in mudstone-siliceous mudstone-silicalite as well as the transitional type of rock assemblage of trench facies.The sources of ore-forming materials include land-based migration and submarine hydrothermal deposition,mainly hydrothermal.The Fushe manganese deposit is a secondary manganese oxide deposit,the Mn element is mainly provided by the sea bottom spout mixing with terrestrial materials.It is deposited by marine hydrothermal sediments and then re-integrated by physical and chemical weathering leaching.