Effects of basic intrusions on REE mobility of sandstones and their geological significance: A case study from the Qianjiadian sandstone-hosted uranium deposit in the Songliao Basin

Petrogenetic Constraints of Early Cenozoic Mafic Rocks in the Southwest Songliao Basin, NE China: Implications for the Genesis of Sandstone-Hosted Qianjiadian Uranium Deposits

“…In the Qianjiadian area, the U mineralization occurs at the redox interface between the primary reduced and the secondary oxidized sandstones (Figure 2b) or close to a secondary reduced green-white zone [18,27,31] related to mafic rock intrusions that are spatially distributed along the redox boundary (Figures 1c and 2b). Besides, the content of U from Yaojia Formation sandstones is inversely correlated with REEs' content [17]. Compared with the sandstones far from the mafic intrusions, the sandstones near the mafic intrusions are obviously depleted in REEs [17].…”

“…Besides, the content of U from Yaojia Formation sandstones is inversely correlated with REEs' content [17]. Compared with the sandstones far from the mafic intrusions, the sandstones near the mafic intrusions are obviously depleted in REEs [17]. Regionally, sediments of the Yaojia Formation were deposited under a hot and dry climate; hence, resulting in the primary oxidation of part of these sediments (Figure 3a) [64].…”

“…Uranium ore bodies with an average grade of 0.0104% to 0.0287% are mainly tabular or lenticular in shape [42]. The ore-hosting sediments are mainly composed of fine-grained sandstone, siltstone, and mudstone with pitchblende and coffinite as the predominant uranium minerals [15][16][17][18][19][20]. Intrusive mafic rocks are also widespread in sandstones of the Yaojia Formation in the Qianjiadian area ( Figure 1c).…”

“…The Qianjiadian uranium deposit has been widely regarded as a typical interlaminar oxidation zone-type uranium deposit in the southern part of the Songliao Basin (Figure 1) [14][15][16]. Many publications have documented the sedimentary facies, depositional environment, sandstone petrography and geochemistry, mineral paragenesis and textures, mineralization geochronology, and ore genesis model for the deposit [17][18][19][20][21]. In the Qianjiadian area, uranium is mainly adsorbed or reduced on carbonaceous debris or migrated oil, and U minerals such as pitchblende and coffinite are intimately associated with iron disulphides [22][23][24][25][26][27].…”

“…Several studies were conducted on the micromorphological observations, in situ sulfur isotope analysis of pyrites, and carbon isotope composition of calcite cement, emphasizing the role of bacterial sulphate reduction (BSR) in the genesis of the U mineralization in the Qianjiadian area [28][29][30][31][32][33]. Nevertheless, the tabular U ore bodies in the Qianjiadian deposit are spatially associated with secondary reduced gray sandstones or bleached white sandstones [34] ( Figure 2) together with the widely distributed mafic rocks [17], which significantly differ from the two predominant models of redox front sandstone-hosted U deposits presented in [33]. In addition, detailed petrographic studies performed on carbonaceous debris from this deposit showed significant increase of the vitrinite reflectance, suggesting that the U mineralization is spatially associated with the alteration halo of the diabase dikes [20].…”