Uranium mineralization formed through multi-stage superposition: Case of the Qianjiadian deposit in Songliao Basin, China

The Qianjiadian uranium deposit is located in the Kailu Depression of Songliao Basin.It is a large-scale in-situ leachable uranium deposit of sandstone type and provides a typical case of the uranium deposits in the Songliao Basin.Here we analyze the impact of oil and gas on reduction alteration,and factors including low grade mineralization.The Qianjiadian uranium deposit is characterized as a typical rolltype deposit with interlayers in oxidized zone.The occurrence of reductive low-permeability sandstone in uranium reservoirs controls the morphology of the uranium-rich orebody.We propose a metallogenic model involving multi-stage superposition characterized by“primary sediment enrichment-interlayer oxidation-superimposed transformation”.Our model would be helpful for formulating guidelines in the exploration for sandstone-type uranium deposits in the Songliao Basin.

蓬莱9-1潜山储层岩性识别及油气富集特征

通过岩石薄片鉴定和岩石化学分析等手段,识别出蓬莱9-1油田潜山钻遇两套岩石组合。一是中新元古界中低级变质岩围岩,包括变质石英砂岩、石英岩、云母石英片岩等;二是花岗岩侵入体。花岗岩锆石LA-ICP-MS U-Pb定年结果显示,所测锆石206Pb/238U年龄集中于162~169 Ma,其加权平均年龄为165 Ma,该年代代表了花岗岩的形成时代,即该岩体于中侏罗世侵入到中新元古界地层。在岩矿鉴定和年代分析的基础上,通过各类岩性岩石物理特征研究,建立了该潜山带岩石的测井识别方法。分析了储层成因及控制因素,并提出了有利油气富集区带,为油气储量申报等奠定了基础。