Abstract:

The Dajing deposit in Linxi County，Inner Mongolia Autonomous Region，China，is a large scale Sn-Cu-Ag-Zn-Pb deposit in the southern section of the Da Hinggan area where Jurassic-Cretaceous volcanic-plutonic rocks are wide spread.So was regarded as epigenetic hydrothermal deposit in genetic  connection with the Mesozoic magmatism. By studying geochemical characteristics of the Dajing deposit associated with some deposit geological characteristics, the following research achievements have been obtained:(1)a geochemical study on geochemical compositions，trace elements and rare earth elements on the ores and mineral from the Dajing Sn-polymetallic deposit showed that the deposit might be of syngenetic hydrothermal sedimentary origin；(2)the relationship between carbon and oxygen isotopes in hydrothermal sedimentary rocks were comparable overall with many sedex-type sulfide ores and associated exhalites，implying a similar genesis for these deposits;(3)the lead isotope data of the ores indicate that subaqueous exhalative mineralization occured during the basin evolution at the Permian time in the Dajing deposit.

Key words: geochemical evidence, exhalative genesis, the Dajing Sn-polymetallic deposit, Inner Mongolia