Characteristics Of The Rare Earth Elements‘ Accumulation Of Phosphorus Rock Series During The Early Cambrian,Guizhou Province

The Early Cambrian is another important phosphorus-forming period after Doushantian.Phosphorites formed during this period are widely distributed in Asia,Western Europe,North America,and Oceania,which is characterized with the enrichment of Ni-Mo polymetallics that reflects global ocean anoxic events as well as the REEs.Phosporites formed during the Early Cambrian in Guizhou is widely distributed in Zhijin?Jinsha?Zunyi and Tongren,they all contain abundant rare earth resources,especially medium and heavy rare earths resources.High-level researches on phosphorites and rare earth elements have been carried out by researchers and achieved a lot of results.However,it is still unclear that the origin and enrichment mechanisms of rare earth elements in phosphorites,sedimentary response of different phase zones,as well as the relationship with redox conditions.In this paper,four typical sections?Zhijingge Zhongwu of shallow-water sedimentary facies section,deep-water sedimentary facies sections such as Bahuang in transitional facies section,ZK102 of Songtao Daotuo manganese mining area and ZK205 in Tianzhu Yundong barite mining area of deep-water facies section?are taken as the research objects.On the basis of comparison of different sedimentary characteristics of phosphorus-bearing rock series,a continuous section from deep-water to shallow-water environment is established,the relationship between?REY and the content of P₂O₅ as well as the index of redox sensitive elements were compared and analyzed horizontally as well.The results show that,the total amount of rare earth elements??REY?and the content of P₂O₅ are highly related with each other in the longitudinal direction of Gezhongwu and Bahuang.Neither the total rare earth elements??REY?nor the content of P₂O₅ has synergistic changes with redox sensitive elements.Linear regression of?REY and P₂O₅ vs.indicators of redox sensitive elements,shows that the total amount of rare earth elements??REY?has a significant positive correlation with the content of P₂O₅,implying a close connections in genesis between each other;both the total amount of rare earth elements??REY?and the content of P₂O₅ are not significantly related with the redox sensitive element index,indicates that the enrichment of rare earth elements is not necessarily related with the redox conditions of sedimentary medium.NASC-normalized REE+Y patterns of phosphorite samples from Gezhongwu and Bahuang are“hat shape”,and relatively enriched in middle rare earth elements?MREE?.Due to the closely radii,ions of the medium rare earth elements?MREE?are easier to displace calcium ions and enter the apatite lattice than other rare earth ions during the diagenesis.As a result,NASC-normalized REE+Y patterns are?hat shape?and the phosphorites are relatively rich in the middle rare earth elements?MREE?.