Source analysis of sandstone type uranium minerals in Louzhuangzi area, southern margin of the Junggar Basin

The Junggar Basin, located in northwestern China, has garnered significant global attention due to its substantial reserves of sandstone-type uranium deposits. The sandstone type uranium deposits (spots) within the Junggar Basin are predominantly concentrated in the surrounding regions of the basin, with the primary ore-hosting strata identified as Jurassic and Cretaceous. However, there exists ongoing debate regarding the understanding of sediment sources, which is of pivotal importance for guiding uranium exploration. In this study, U-Pb dating, whole rock geochemical analysis, heavy mineral analysis, and in-situ Hf isotope composition were employed, in conjunction with sedimentology and tectonic setting, to trace the provenance of sandstone type uranium deposits in the Toutunhe Formation of the Middle Jurassic in the central-southern part of Junggar Basin. The research indicates that the sandstone debris is characterized by high concentration of feldspar and rock fragments, with volcanic rock debris being the dominant constituent. Geochronological analysis of detrital zircons reveals that the age spectrum of detrital zircons in the Toutunhe Formation exhibits a primary peak ranging from 335 to 370 Ma, with a notable peak at 355 Ma, and two secondary peaks at 395 to 475 Ma and 262 to 316 Ma, respectively. The heavy mineral assemblage, comprising zircon, garnet, apatite, and magnetite, suggests that the source area is primarily composed of acidic magmatic or metamorphic rocks. By systematically comparing the U-Pb age and Hf isotope results with previously reported data from adjacent geological units in the southern Junggar Basin, and integrating the ZTR index and paleocurrent direction, the analysis demonstrates that the principal source area for the sandstone of the Toutunhe Formation is Bogda Mountain, particularly the uranium-rich felsic rocks, and the secondary area is Tianshan Mountain.Overall, this study provides essential and incisive insights into inferring the source supply areas and transportation pathways, thereby holding considerable significance for uranium exploration endeavors within sedimentary basins on a global scale.