鄂尔多斯盆地西南部下白垩统赋矿砂岩中有机质地球化学特征及其来源OACSTPCD

Sandstone-type uranium deposits are the most important uranium deposit type in China and are commonly associated with organic energy resource.Ordos Basin is one of the typical basins where organic and inorganic resources coexist.In recent years,new uranium mineralization has been discovered in the Lower Cretaceous Huanhe and Luohe Formation in Zhenyuan area,in the southern part of the basin,which is closely related to organic matter.To determine the nature and source of organic matter in mineralized sandstones and explore its relationship with uranium mineralization processes,organic petrological and organic geochemical analyses were conducted on typical samples.The results indicates that the organic matter in the ore-bearing sandstones was predominantly"mobile or disseminated organic matter".The characteristics of biomarkers indicated that organic matter was relatively low mature,formed in a reductive low-salinity lacustrine environment,and its bio-precursors were dominated by lower aquatic organisms.Oil-source correlation analysis revealed that the organic matter was originated from the highly prolific lacustrine source rocks of the 7th member of the Yanchang Formation(Chang-7 member).