Sedimentary features and uranium metallogenic conditions of Yaojia formation in southern Songliao basin

Songliao basin, NE China, is a large basin containing oil-gas and uranium ore. The upper cretaceous Yaojia formation is widely distributed at the south part of Songliao basin. It is moderately buried and its sedimentary system consist mainly of fluvial plain, braided river, delta and lacustrine. It has stable mud-sandstone-mud sequence structure and stable thickness of sandbodies. It has high content of organic matter, reduce capacity and uranium. The humid to semi-humid paleoclimate in the sedimentation epoch of Yaojia formation was favorite for the formation of uranium rich strata. Yaojia formation has perfect hydrodynamic system of recharge-run off-discharge and it has good conditions of epigenic reworking and alteration. Comprehensive analysis shows that it has good potential for uranium metallization. It is the key targe layer in southern Songliao basin. (authors)