Features And Relationship Of Hydrothermal Cryptoexplosive Breccia With Uranium Mineralization In Baimadong Ore Deposit

The uranium polymetallic of Baimadong deposit is one of typical carbonaceous-siliceous-argillitic rock type uranium deposit in our country. In the mining area, faults are very commom and folds are not common, through multiple stage hydrothermal alteration, alteration types are various, and it is mainly silicification, black alteration, secondly, reddening, calcilization, and baratization. The predecessors have a deep research for the metallogenic geological background and cause of this ore deposit, and they think the research of ore-controlling structure is the key to the next step prospecting breakthrough in the area. Through detailed field investigations, we find that the hydrothermal cryptoexplosion system plays an important role in mineralization. On the basis of field geological investigation, by the study of the analysis of major element, trace elements, carbon and oxygen isotopes of Baimadong deposit and the microscopic observation, it is concluded that the follow understandings:Baimadong deposit exists a lot of cryptoexplosive breccia that it is closely associated with mineralization, it is mainly irregular cystic, tubular distribution in space, a nearly elliptic distribution on the plane, general funnel shaped, tubular distribution In the section. The degree of crushing of the cryptoexplosive breccia is from strong to weak outward from the core. Powder rock is in the centre, and the energy of cryptoexplosive role decreases gradually, which is gradual transition to the shatter cataclastic rock band formed by hydrothermal filling.In the space, the coupling of black alteration, red alteration and hydrothermal cryptoexplosion breccia is the part of rich large uranium mineralization. Major element analysis indicates that red alteration may be mainly associated with the enrichment of hematite, black alteration is mainly related to the silicide, which is associated with uranium ore formation, there is no obvious cryptoexplosive breccia and uranium mineralization, however, the hydrothermal fluid in the cryptoexplosion breccia bring into more elements and minerals, such as barite, haematite, silicification,etc. Characteristics of trace and rare earth elements of the surrounding rock and hydrothermal vein body of the mining area indicates that the source of the surrounding rock and hydrothermal fluid is inconsistent. carbon and oxygen isotopes prove that the fluid source of calcite vein is consistent and has the characteristics of mantle source, these calcite vein exist in black alteration, red alteration and cryptoexplosive breccia, the formationof Baimadong ore deposit is not formed by sedimentation, leaching, the transformation in the surrounding rock of subcutaneous layer, but is a hydrothermal deposit.On the area, Uranium-Hg polymetallic mineralization has certain zonality, the combination of high temperature elements is rich in the southeast, and the combination of medium and low temperature elements is rich in the northwestern, which implies ore-forming fluid the characteristics of the migration from deep to shallow, from southeast to northwest. The deep of the southeast of this mine has bigger metallogenic potentiality.