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.

The Erlian basin is one of the most important basins in northern China to host sandstone-type uranium deposits (SUDs), in which Bayanwula, Saihangaobi, and Hadatu are under development, to name a few. Issues such as the metallogenic mechanism and mineralization of these deposits need to be addressed throughout the mining process. Over the past several decades, 2D and 3D seismic reflection surveys have been carried out to study these typical SUDs. The seismic technique has become the most effective geophysical tool of uranium (U) exploration, and it is used to develop our understanding of the stratigraphic configuration, faults, and sandstone contents of target layers in uranium environments. In addition, seismic interpretation could yield useful suggestions regarding the subsequent drilling program in the work area. There are two seismically predictable patterns of SUDs, named “Big depression + fault” and “Large-angle unconformity + fault”, which have been established following detailed seismic research in this basin. The characteristics of these faults are as follows: (1) the “‘U’-shaped formation” is conducive to the inflow of O-U-bearing groundwater into the target sandstone; (2) the “Big depression of reductive formation” provides plenty of organic matter (containing reducing media and U pre-enrichment) to promote redox reaction mineralization; (3) “Large-angle unconformity” is favorable to the migration of reducing substances, consequently leading to an enhancement in redox U mineralization; (4) “faults with long-term activity” become rising channels for reducing the presence of fluids and gases at depth; and (5) “sandstone and its scrambled seismic facies”. The results also offer indirect evidence of a connection between hydrothermal fluids and U mineralization; a hypothesis of “hydrothermal effusion” mineralization is proposed accordingly. In conclusion, seismically produced images of geological structures and sandstone distribution could yield important information for U prospecting and mine planning; it is worth considering seismic technologies in the future exploration of SUDs.

Due to the absence of early magma records in pegmatites, it is difficult to investigate the behavior of Nb and Ta during the transformation from magma to pegmatite melt. Zircon megacrysts in an NYF-type (Nb-Y-HREE-F) pegmatite from the Arabian Shield could be divided into three phases from core to margin. The Phase Ι zircon in the core of the zircon megacrysts had typical magma oscillatory zonation with ∑REE content from 300 to 400 ppm, Th/U ratios of less than 0.1 and Nb/Ta ratios of less than 1.0. Phase ΙΙ zircon had oscillatory zonation and was enriched with LREEs mostly with Th/U ratios of 0.1–0.2 and Nb/Ta ratios of 1.0–3.0. Phase ΙΙΙ unzoned zircon had the highest ∑REE content, from 8000 to 15,000 ppm, with Th/U ratios higher than 3.0 and Nb/Ta ratios higher than 5.0. The Hf-O isotopic composition was similar in the different phases of zircon with initial ¹⁷⁶Hf/¹⁷⁷Hf ratios of 0.28258–0.28277, εHf(t) values from 8.0 to 12.0 and δ¹⁸O_VSMOW from +4.0‰ to +5.0‰. Zircon megacrysts in the NYF-type pegmatite from the Arabian Shield record the transformation from magma to pegmatite melt. Similar Hf-O isotopic compositions mean a closed magmatic system without contamination by external melt, rock or fluid. The proposed modeling shows that magma with low Nb and Ta concentrations and Nb/Ta ratios could evolve into residual pegmatite melt with a high Nb content and superchondrite Nb/Ta ratio during several stages of melt extraction and fractional crystallization of Ti-rich minerals, such as rutile and titanite. The Nb/Ta ratio can be used as an effective indicator of the transformation process from magma to pegmatite melt.

Situated between the Altyn Tagh and Eastern Kunlun ranges, the western Qaidam Basin records Cenozoic sediment-routing changes associated with the growth of the northern Tibetan Plateau. However, the provenance of post-Miocene strata in this region remains debated, and the role of sediment recycling has not yet been quantitatively constrained. Here, we integrate field observations, sandstone petrography, quantitative detrital zircon U-Pb analysis, and inverse Monte Carlo modeling to compare Late Cenozoic strata in the Qigequan area with nearby Mesozoic strata and basement sources in the Altyn Tagh and Eastern Kunlun ranges, thereby assessing direct versus recycled sediment supply. Sandstones of the Qigequan and Shizigou formations are poorly sorted and contain angular to subangular quartz and feldspar grains and identifiable sandstone and mudstone lithic fragments, indicating erosion of pre-existing sedimentary rocks. Their detrital zircon age spectra are dominated by 300–600 Ma grains (57.9%–69.0%), followed by subordinate < 300 Ma grains (18.4%–21.1%) and minor 600–1000 Ma (6.9%–13.2%), 1000–1500 Ma (1.3%–3.9%), and >1500 Ma (1.3%–3.9%) components. Similarity metrics and multidimensional scaling (MDS) analyses show that the Cenozoic age distributions are substantially more similar to the composite Mesozoic proxy than to the Altyn Tagh or Eastern Kunlun basement endmembers. Inverse Monte Carlo modeling further shows that a three-endmember model incorporating the composite Mesozoic proxy provides a better fit than the two-endmember Altyn Tagh–Eastern Kunlun model. Across the three optimization metrics, the composite Mesozoic proxy contributes approximately 36%–68% and 61%–72% to the modeled detrital zircon age distributions of the Shizigou and Qigequan formations, respectively. Together, these results support a substantial role for recycled Mesozoic material in the Late Cenozoic sediment-routing system of the western Qaidam Basin, providing new provenance constraints on basin–range coupling along the northwestern margin of the Tibetan Plateau.

The origin and metallogenic role of pyrite in sandstone-hosted uranium deposits remain difficult to constrain because pyrite may record both early diagenetic reduction and later ore-fluid overprinting. Here, pyrite and associated uranium minerals from mineralized and barren sandstones of the Middle Jurassic Zhiluo Formation in the Yahewan uranium deposit, southern Ordos Basin, were investigated using petrography, SEM-BSE imaging, EPMA, LA-ICP-MS trace-element analysis, and in situ sulfur isotope analysis. Pyrite occurs mainly as framboidal, colloidal, pore-filling, fracture-filling, and massive aggregates and is commonly associated with organic matter and coffinite or coffinite-like U-silicate minerals. Most pyrite domains show low Co/Ni ratios, suggesting a predominantly authigenic to sedimentary–diagenetic origin. High U, Mo, V, W, Se and As occur mainly in pyrite-rich microdomains, but high-U analyses are interpreted cautiously because some signals may include contributions from adjacent coffinite or coffinite-like U-silicate phases, fracture-hosted uranium minerals, or mixed ablation. Together, the petrographic, trace-element and sulfur isotope data support a two-stage model in which early organic matter and authigenic/biogenic pyrite created local reducing microenvironments that were later overprinted by U-bearing basinal fluids.

Polymetallic enrichment layers are commonly found at the base of the Lower Cambrian and extensively distributed across the Upper Yangtze Platform, yet their genetic models remain controversial. This study systematically collected samples from a typical section in the southeastern Chongqing region for mineral, organic, and inorganic analyses. It investigates the relationship between the abundance of various trace metal elements and organic matter at the base of the Niutitang Formation, as well as the vertical distribution characteristics of organic carbon isotopes and organic matter features. The results indicate that the Niutitang Formation shale exhibits a distinct three-part structure from bottom to top. Various metal elements are enriched in the lower interval, showing a close correlation between the abundance of polymetallic elements and the carbon isotopes of shale organic matter. The middle interval contains the highest TOC value and the lowest Ti/Al ratio, while the upper interval shows a significant decrease in organic matter abundance, with a clear positive correlation between the excess silicon content and Ti/Al ratio. Additionally, the mixing effect of deep-sea upwelling is the primary control on the formation of polymetallic enrichment layers in the lower interval, followed by the adsorption of organic matter under anoxic conditions. The sedimentary environment of the upper interval of the Niutitang Formation trends toward oxidation, with paleoclimate shifting toward colder and drier conditions, exhibiting aeolian sedimentary features that are unfavorable for the enrichment of trace metal elements. Consequently, upwelling is a key factor in the enrichment and mineralization of trace metal elements at the base of the Lower Cambrian in the Upper Yangtze region.