Hydrothermal Alteration Characteristics And Genesis Significance Of Baimadong Uranium Deposit In Guizhou

The Baimadong?504?uranium deposit in Kaiyang,Guizhou Province is located in the south of the?Central Guizhou Uplift?of the?Yangtze Plate and the North of Guizhou Tailong?,and is located on the southwestern margin of the Yangtze Plate.The faults are developed in this area.The ore bodies are mainly produced in the black rock series consisting of the Lower Cambrian Qingxudong Fm gray-yellow,yellow-bearing mica sandy shale,calcareous shale,dark gray limestone and dolomite.Hydrothermal alteration is high intensity,various and complex,uranium mineralization is closely related with hydrothermal alteration.Therefore,the study of the hydrothermal alteration of the mining area is of great significance for the study of the genesis of the deposit and the subsequent prospecting work.Based on the field geological survey,this paper studied the hydrothermal alteration type,altered rock and mineral characteristics of the deposit,the species and transfer degree for each component by using microscopic observation,elemental geochemical characteristics analysis,and the mass-balance calculation of hydrothermal alteration.The following understandings are obtained:?1?The wall rock alteration of the Baimadong uranium deposit is very developed,and there are many stages,and the superposition effect is complicated.The main alteration is black alteration,silicified,calcilization,and red alteration are widely distributed,and baratization and pyritization also distributed.The alteration shows the zoning of the alkali at lower ore belt the acid at upper by vertical direction.?2?The analysis of the geochemical characteristics of the major elements shows that the uranium mineralization is positively correlated with Al₂O₃,TFe and SO₃,and negatively correlated with MgO and CaO.The enrichment of U in black alteration rocks is the most obvious.This may be closely related to?the polymerizer of uranium?such as clay minerals,pyrite,and hematite mineralization.The analysis of trace elements shows that As,Sb,Mo,Tl are obviously associated with U enrichment positively.The analysis of rare earth element characteristics shows that both the wall rock and the altered rock have similar right-dip patterns,indicating that they may have homology.Studies on carbon-oxygen isotope indicate that ore-forming fluids in this area may be related to deep hydrothermal fluids in the earth's crust.?3?Calculating the element mass balance migration of the altered profile,the Isocon graphical analysis shows that the uranium mineralization intensity is directly proportional to the strength of alteration,and the black alteration rock and the red alteration rock's U element entrance is most obvious.In the process of hydrothermal alteration,the elements that obviously moved in are U,SiO₂,Pb,Ge and Cr.The elements that are obviously moved out are MgO,CaO,Mn,Li,Ba,Co,Sr,Ga,Sc,V,Ni,REE etc.;The transfer law of U is positively correlated with Pb,and has a significant negative correlation with the transfer of MgO,CaO,Mn,HREE and other elements.?4?Hydrothermal alteration plays an important role in mineralization and runs through most of the mineralization process.Especially during mineral precipitation to epigenetic oxidation,it has created a good environment for uranium mineralization.Black alteration and red alteration have important indications for prospecting.