Evolution of depositional system and uraniferous characteristics of Damoguaihe Formation in Kelulun Sag

Damoguaihe Formation,which is mainly of alluvial fan,fan delta and lacustrine depositional systems,is the target horizon for the prospecting of sandstone-type uranium deposit in Kelulun sag,Hailaer basin.According to the depositional environment and sediment characteristics,alluvial fan facies is subdivided into upper fan,middle fan and lower fan subfacies;the fan delta facies is subadivided into upper fan delta plain,lower fan delta plain,fan delta front and fan prodelta subfacies.At the northern edge of the sag occurred one fan delta and one alluvial fan,which can mutually transform one into another.The terrigenous coarse-grained clastic deposits in the study area provide favorable condition for the concentration of uranium and especially the main channels and distributary channels on the fan delta and alluvial fan are the most favorable sites for uranium concentration.