Research On Geochemistry Characteristrics And Sedimentary Environments Of The Bahuang Phosphorite Deposit In Tongren,Guizhou

Early Cambrian Phosphorites widely spreading in Guizhou,it mainly distributed in the areas of northern Guizhou,central Guizhou and eastern Guizhou.For a long time,the research on phosphorite rock has always been dominated during the Doushantuo?Late Sinian?and Meishucun?Early Cambrian?.With the deepening of research on phosphorite deposits,it is found that the Early Cambrian phosphorite deposit is highly enriched in rare earth elements and associated with Ni,Mo,V and U in Bahuang,Tongren.The research on the deposit mainly focuses on the metallogenic tectonic environment of the phosphates and the REE geochemical characteristics.There isn't systematic research work on the geochemical characteristics and sedimentary environment of phosphorite.Therefore,the formation environment and geochemical characteristics of the phosphate deposits are explored,which provides a basis for the study of the restoration of the sedimentary environment,the reconstruction of paleogeographical patterns,the enrichment of phosphorus,and the mechanism of metallogenic genesis.It also has important theoretical significance for guiding mineral exploration and multi-mineral exploration.Mineral petrology research on phosphorite deposit by rock ore identification and electron probe microanalyzer,X-ray fluorescence spectrometry and ICP-MS analysis methods were used to conduct geochemical analysis and study the phosphorus rock sedimentary environment.Mainly get the following points:?1?The Bahuang phosphorite deposit is located at the southeastern margin of the Upper Yangtze Platform,and at the bottom of the Cambrian Niutitang Formation.The floor is the siliceous rock of Laobao Formation;the roof is black sandy clay rock;the interbed is Carbonaceous siliceous shale and polymetallic layer.?2?The ore types are concretionary phosphorite,brecciaous phosphorite and layered phosphorite.The ore minerals are mainly collophanite,followed by apatite,the gangue minerals are clay minerals,quartz,calcite,sericite,pyrite,chalcopyrite and organic matter.There are two types of mineral assemblages:collophanite-clay minerals-siliceous mineral and collophanite-apatite-calcite-clay minerals.?3?Phosphorite and rich polymetallic phosphorite have high P₂O₅ content and negative correlation with SiO₂,Na₂O,K₂O and MgO,indicating that the attendance of siliceous and terrigenous materials will inhibit the precipitation of phosphate minerals.The elements of V,Mo,Cd,Sb and U are enriched in phosphorite of the Bahuang.Because Sr enters the phosphate mineral crystal lattice with the isomorphism,the phosphorite has higher Sr abundance than other lithologies.The polymetallic phosphorite.Phosphorus rock series are characterized by a large number of rare earth elements,relative enrichment of LREE,relative loss of HREE,negative Ce anomaly and Eu weak negative anomaly to weak positive anomaly.Rare earth elements are more concentrated in phosphorite and rich polymetallic phosphorite,and?REE is positively correlated with P₂O₅,indicating that the enrichment of rare earth elements should be related to the formation of phosphorite.?4?The sedimentary structure characteristics,mineral assemblage characteristics and lithofacies paleogeography characteristics of the phosphorus rock series indicate that the phosphorite rock series is the gentle slope-continental slope of the platform margin.The sedimentary environment of the lower phosphorite is a relatively shallow water environment;the sedimentary environment of the upper rich polymetallic phosphorite is a relatively deep water and relatively reduction of the platform margin ramp.The sedimentary environment is the hydrostatic reducting environment,from the bottom to the top of the profile,the depth of the sedimentary water is changed from shallow to deep.?5?M characteristics,U/Th,Ni/Co,?U,V/?V+Ni?and Ce anomaly characteristics,Sr/Ba and elements Mn,Ni,Co,Cu of phosphorite and rich polymetallic phosphorite Variation characteristics,Mg/Ca,Al/Ti and Al₂O₃/MgO characteristics reflect sea level decline,the shallower seawater is conducive to the enrichment of phosphorus,the sedimentary water environment of the phosphorite and polymetallic phosphorite is a reducing environment from brackish water to normal seawater salinity,and the paleo-climate environment is a humid climate.