Geochemical Characteristics Of The Lower Cambrian Qiongzhusi Formation Black Rock Series In The Huize Area, Northeastern Yunnan

Because of their special sedimentation,the black rock series are often rich in many useful elements,which often form phosphorus deposit,barite deposit;V-Cu,Ni-Mo-PGE and U deposit deposits and so large-scale metal and non metal deposit.The black rock series has become one of the hot research fields in current academic circles.The black rock series developed widely in the lower Cambrian Qiongzhusi formation Yunnan Huize area.Applying the theory and method of sediment logy,sequence stratigraphy and geochemistry,based on field geological survey and regional geological background analysis.This paper systemically studies mineralogical characteristics,major elements,REE and trace element geochemistry of the lower Cambrian Qiong zhusi formation of the black rock series of Huize.The main achievements of this study are as follows:1.Based on the area of geological survey,profile measurement,indoor rock mineral identification,combing with previous studies and data summary and analysis.The black shale litho logy composition and distribution of the lower Cambrian Qiong zhusi formation of Huize area are clear.Black rock series of the Qiong zhusi formation litho logy is mainly composed of siliceous siltstone and argillaceous siltstone and carbonaceous shale and carbonaceous mudstone composition containing Lepidoptera sandstone2.Through the ancient geography,sea-level and sedimentary fancies analysis,combined with the regional geological background,there is an Kangdian old land,Jiangnan shale basin,Southeast elastic platform,in the lower Cambrian Qiongzhusi formation sedimentary period.The overall pattern of Pale geography is that the southwest is high,the East-West is low.From west to East,the sea gradually deepened.The sedimentary environment is mainly low energy and anoxic environment.Through the analysis of the basic sequence,the black shale deposition zone of Huize in the lower Cambrian Qiong zhusi formation is shallow shelf sedimentary environment.3.The organic carbon of black rock series of Qiongzhusi is 1.45%?7.37%,The content of SiO2 was 55.13%?68.98%(except for the sample of mineralized layer),the content of Al2O3 was from 12.81%to 18.65%,and the content of BaO was 0.08%?0.19%.Through systematic analysis the ratio of main elements MnO/TiO2?(Al2O3)N/(Al2O3+Fe2O3)N?(SiO2)N/(Al2O3)N?(Si)N/(Si+Al+Fe)N?(Al)N/(Al+Fe+Mn)N and Fe2O3/TiO2-Al2O3/(Al2O3+Fe2O3).The black rock series in the study area are formed in the continental margin environment.The source of sediment is nearby erogenous elastic matter,and the local or horizon is supplemented by biological or hot water action.4.There is different levels enrichment about rare earth element in the black rock series of lower Cambrian Qiongzhusi formation.REE ranged from 127.47 to 316.10 ×106,and the ratio of LREE/HREE was 6.90 to 12.27,the fractionation of heavy and heavy rare earths is obvious,and the normalized curve of North American shale is flat,Relative to North American shale,Delta Ce is negatively negative,while Delta Emu is a weak positive anomaly.Comprehensive analysis of delta,Ce,Delta,Eu,La/Ce ratios,La/Yb-Ce/La diagrams,and La/Yb-REE diagrams.The Huize area of Qiongzhusi black rock series formed in anoxic environment,the formation of sediments associated with hot water.5.The trace elements of black rock series in Huize area are compared with crustal elements abundance,U?V?Cs?Mo?Cd?Ag?Au?Ba?Th?Hf?Pb?Pd?Rb?Zr?Ga?Ni?Zn?W?Sn?Pt,Such elements are enriched in different degrees,the enrichment coefficients of Mo and U were 55.66 and 24.81 times,he primary mantle normalization of trace elements shows that the elements of U and Pb are obviously enriched,while the elements of Nb and Sr are obviously deficient,while Ce and Eu are relatively weak,while Th,La,Nd,Hf and Gd are relatively weakly enriched.The contents of Ba?U and Mo in sedimentary rocks of black rock series,Zn-Ni-Co graphic?U-Th and Co/Zn-(Co+Ni+Cu)graphic and the ratio of U/Th?Co/Zn?(V)N/(V+Ni)N?(Sr)N/(Ba)N?(Cu)N/(Zn)N,the whole system is characterized by hypoxia and reducing and hot water environment.