Sedimentary Tectonic Evolution and Uranium Mineralization of Post Late Cretaceous in Shaogen Area of Lujiapu Sag, Kailu Basin

Key words: 
• uranium mineralization /
• sedimentary tectonic evolution /
• Shaogen area /
• West Lujiapu sag /
• Kailu Basin

Abstract: As one of the major coal and uranium bearing basins in Northern China, Kailu Basin, which locates in the southwest of Songliao Basin, has always been an emphasis area for uranium exploration. Based on a large number of gamma anomalies found in the coal exploration in Shaogen area of Kailu Basin, a uranium geological survey launched few years ago and some uranium mineralization points were discovered. In this case, researches such as detailed stratigraphic correlation, serious analysis of sedimentary environment and tectonic evolution, discussion of uranium mineralization characteristics have been carried out. In view of the above comprehensive analysis, we get four main conclusions:①Shaogen area developes Fuxin, Yaojia, Nenjiang, Sifangtai and Taikang Formation from the bottom up with absence of Quantou to Qingshankou Formation and Mingshui Formation. ②Fuxin stage is in the end of fault depression period developing lacustrine swamp environment with several layers of coal; whilst due to compression and uplifting after Fuxin period, there has been no sediments from Quantou to early Yaojia Period; then it switches into a slight extensional environment and deposits lacustrine silt in Nenjiang stage; accompany with the following structrral inversion, alluvial fan deposits in the Sifangtai Formation. ③Both Nenjiang and Sifangtai Formation are the uranium ore-bearing strata, while mudstone type uranium develops in Nenjiang Formation and sandstone type uranium in Sifangtai Formation. ④Mudstone type uranium orebody which locates in trasition zone of the yellow green and gray mud in the up of Nenjiang Formation presents a thin plate with a central downward concave shape, indicating a synsedimentary deposition; While sandstone type uranium orebody which locates in transition zone of reddish brown and gray green sandy conglomerate in the bottom of Sifangtai Formation presents a short plank shape and may illustrate a phreatic oxidation type mineralization. These research results have the extensive applicability and practical instruction significance in Uranium exploration of Shaogen area.