Abstract: The environment of the primary sedimentary medium in the sedimentary strata is of great significance to the mineralization and potential analysis of sandstonetype uranium deposits. In this study, trace element analyses of 16 mudstoness derived from the  Upper Cretaceous to Neogene in the uranium geological exploration well N3006 in the north of Junggar basin, were conducted. By combination with observations form outcrops and drill cores, the lithium (Li), strontium (Sr), gallium (Ga), barium (Ba) Copper (Cu), uranium (U), vanadium (V), nickel (Ni) and other trace element indicators are utilized to discuss the environmental evolution characteristics of the Late Cretaceous to Neogene sedimentary media in the study area and their constraints on uranium mineralization. All the results suggest that, the paleosedimentary environment from the Late Cretaceous to Neogene was generally characterized by dry, hot and oxygen rich fresh water brackish water deposits; Judging from the primary sedimentary environment, the sand bodies of each formation from Upper Cretaceous to Neogene in the study area are generally not conducive to the development of traditional interlayer oxidation and phreatic oxidation sandstonetype uranium mineralization; However, the presence of strongly oxidized paleoenvironment is conducive to the migration of uranium elements. Significantly, the primary gray layer formed in a local special environment and the gray layer transformed by reducing fluid in the later period are the important breakthrough directions for the exploration of sandstone type uranium deposits in the area.

Key words:  , Late Cretaceous, Neogene, mudstone, trace elements, evolution of paleosedimentary environment, uranium mineralization, Junggar basin