To further explore the uranium-bearing prospects of the Zhiluo Formation, the petrography, major elements, trace elements and rare earth elements of Zhiluo sandstone samples collected from four boreholes were analyzed in this research to determine the provenance, tectonic setting and paleoweathering of the formation. The results of the analysis reveal that the Zhiluo Formation sandstone comprises primarily feldspar sandstone, with quartz, feldspar, and mica as the main mineral components. The rare earth elements are mainly characterized by enrichment in light rare earth elements and loss of heavy rare earth elements. The ratio of light to heavy rare earth elements (LREEs/HREEs) is 5.55–7.79, with an average of 6.33. The value of (La/Yb)_CN is 12.96–22.33, with an average value of 17.41, indicating obvious fractionation of LREEs and HREEs. The chemical index of alteration (CIA) value of this sandstone is 56.30–63.04, with an average of 59.75, which indicates that the parent rock experienced weak chemical weathering in a dry climate. The discrimination diagrams of the source area and parent rock show that the source area of the Zhiluo sandstones had a mixed intermediate-felsic composition, and that the main parent rocks were andesite and granite. The tectonic setting discrimination diagram indicates that the tectonic setting of the source area was the passive margin. Thus, the provenance of the sandstone of the Zhiluo Formation is proposed to be the volcanic-sedimentary rock series developed on the northern margin of the Ordos Basin.

In adjustment to fulfill the requirements of the investigation regarding the lower Cretaceous sandstone uranium deposit in the Naogaodai area within the northwest of Ordos Basin, twenty-seven sandstone samples obtained from the Lower Cretaceous Huanhe Formation were analyzed for major, trace and rare earth elements (REE). The source of clastic and tectonic background was additionally analyzed. The results show that Huanhe sandstone is feldspar rich sandstone, and also the mineral composition is principally quartz, albite and plagioclase; the ratio of light to heavy rare earth elements (LREE/HREE) is 9.25–10.83, with an average value of 10.00; (La/Yb)_CN is 10.20–12.53, with an average value of 11.24, demonstrating that LREE is enriched and fractionated compared with HREE. REE distribution patterns are similar, which additionally reveals that Huanhe sandstone has a homogenous source; the Index of Compositional Variability (ICV) value is 1.17–1.73, with an average value of 1.35, both greater than 1, showing an immature property, which may be first-order cycle deposition. The average value of the Chemical Index of Alteration (CIA) is 50.29, suggesting that the source rock has encountered weak chemical weathering; sandstones are near-source first-cycle provenance, which is not significantly influenced by sedimentary sorting and recycling. The geochemical qualities further indicate that Huanhe sandstone was deposited in a passive margin and experienced moderate weathering.

This study aims to analyze the provenance of Middle Jurassic Zhiluo Formation sandstones exposed by drilling in the northern Ordos Basin (Bayingqinggeli area) and reconstruct the tectonic setting, paleoclimate, and paleoweathering conditions of their source rocks through integrated petrographic and geochemical analyses (major, trace, and rare earth elements). Comprehensive evaluation of mineral assemblages and geochemical signatures reveals that the detrital components of the studied sandstones were predominantly derived from multiple recycled felsic (granitic) igneous sources, with subordinate contributions from intermediate igneous (granodioritic), metamorphic (gneissic), and mafic igneous (andesitic) provenances. Diagnostic elemental ratios including La/Sc, Th/Sc, and Co/Th demonstrate a principal derivation from felsic lithologies (granites and gneisses) coupled with recycled quartzose sedimentary sources. Chondritenormalized REE patterns exhibit light REE (LREE) enrichment, flat heavy REE (HREE) distributions, and pronounced negative Eu/Eu* anomalies, showing close affinity to Upper Continental Crust (UCC) characteristics dominated by felsic lithologies. Geochemical proxies and trace element ratios (e.g., Th/U, Th/Sc) indicate that the source area underwent moderate to intense chemical weathering, primarily under arid climatic conditions with intermittent episodes of warm, semi-humid to humid paleoenvironments. The integrated dataset further suggests a complex exhumation history involving cratonic basement uplift and reactivation of Paleozoic orogenic belts during the Mesozoic era.