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Karst bauxite is a major source of aluminum and contains high concentrations of trace elements such as Li, Ga, Sc, and rare earth elements (REEs). It is regarded as a potential non-conventional REE source due to the increasing demand for REEs. This study provides new mineralogical and geochemical evidence of a Lindai bauxite deposit in central Guizhou Province, aiming to analyze the genesis of REE minerals and reveal the forms of REEs occurring in these deposits. The results indicate that a large number of detrital and authigenic rare-earth phosphate minerals, including monazite and xenotime, were identified. In terms of their genesis, the authigenic monazite was mainly precipitated under alkaline and reducing conditions, whereas the authigenic xenotime was formed in acidic and reducing conditions. The mineralogical evidence detected by scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) and a TESCAN Integrated Mineral Analyzer (TIMA) suggests that the REEs in the Lindai bauxite exhibit multiple forms, including rare-earth phosphate minerals (monazite and xenotime) and REE scavenging by hematite and anatase phases. Among them, the anatase controls some LREE (such as La, Ce, and Pr) distributions in addition to monazite, whereas the hematite also controls relatively large amounts of Sm, Eu, and HREE (such as Gd, Tb, Dy, Ho, Er, Tm, and Lu) distributions. According to the calculation of the percentage of REE-bearing mineral phases obtained by a TIMA analysis, REE scavenging by hematite accounted for 93.28% of all forms of REEs, REE scavenging by anatase accounted for 5.88%, monazite accounted for 0.67%, and xenotime accounted for 0.17%. This study provides new evidence of the forms of REEs occurring in Carboniferous karst bauxite in central Guizhou Province. [ABSTRACT FROM AUTHOR]

The Zunyi manganese deposits, which formed during the Middle to Late Permian period and are located in northern Guizhou and adjacent areas, are the core area of a series of large‐medium scale manganese enrichment minerogenesis in the southern margin and interior of the Yangtze platform, Southern China. This study reports the universal enrichment of rare earth elements (REEs) in Zunyi manganese deposits and examines the enrichment characteristics, metallogenic environment and genesis of REEs. The manganese ore bodies present stratiform or stratoid in shape, hosted in the silicon–mud–limestones of the Late Permian Maokou Formation. The manganese ores generally present lamellar, massive, banded and brecciated structures, and mainly consist of rhodochrosite, ropperite, tetalite, capillitite, as well as contains paragenetic gangue minerals including pyrite, chalcopyrite, rutile, barite, tuffaceous clay rock, etc. The manganese ores have higher ΣREE contents range from 158 to 1138.9 ppm (average 509.54 ppm). In addition, the ΣREE contents of tuffaceous clay rock in ore beds vary from 1032.2 to 1824.5 ppm (average 1396.42 ppm). The REEs from manganese deposits are characterized by La, Ce, Nd and Y enriched, and existing in the form of independent minerals (e.g., monazite and xenotime), indicating Zunyi manganese deposits enriched in light rare earth elements (LREE). The Ceanom ratios (average –0.13) and lithofacies and paleogeography characteristics indicate that Zunyi manganese deposits were formed in a weak oxidation‐reduction environment. The (La/Yb)ch, Y/Ho, (La/Nd)N, (Dy/Yb)N, Ce/Ce* and Eu/Eu* values of samples from the Zunyi manganese deposits are 5.53–56.92, 18–39, 1.42–3.15, 0.55–2.20, 0.21–1.76 and 0.48–0.86, respectively, indicating a hydrothermal origin for the manganese mineralization and REEs enrichment. The (δ13CV‐PDB (−0.54 to −18.1%) and (δ18OSMOW (21.6 to 26.0%) characteristics of manganese ores reveal a mixed source of magmatic and organic matter. Moreover, the manganese ore, tuffaceous clay rock and Emeishan basalt have extremely similar REE fractionation characteristic, suggesting REEs enrichment and manganese mineralization have been mainly origin from hydrothermal fluids. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ore-forming fluids originated from ELIP volcanism-related hydrothermal activities. • The sedimentary environment likely evolved from anoxic through suboxic to oxic. • Permian Mn mineralization led by ELIP-induced tectono-hydrothermal activities and redox changes. The Permian manganese (Mn) ore belt lies in western South China Block, and contains many large-medium Mn deposits. However, the genesis and metallogenic mechanism of these deposits remains a matter of debate. Here we shed light on this issue based on new mineralogical, geochemical, and Sr isotope data from the Changgou Mn deposit in the Zunyi orefield (Guizhou, SW China). The Mn orebodies occur as lenses and layers, and are hosted in carbonaceous-siliceous limestone, carbonaceous mudstone, and tuffaceous claystone. The ores show a variety of structures (e.g., detrital, brecciated, massive, and banded) and complex mineral compositions (e.g., galena, sphalerite, siegenite, molybdenite, barite, rutile, and monazite). The ore samples are characterized by chalcophile and siderophile element enrichments, low Al 2 O 3 /TiO 2 ratios (mean 10.36), high and varying Mn/Fe ratios (1.26–4.71), distinctly high REY (rare earth and yttrium) contents (mean 766.46 ppm), and high La/Ce (mean 1.04) and low Y/Ho (mean 28.17) ratios. The footwall and ore samples have 87Sr/86Sr ratios of 0.706897 to 0.707093. Integrated mineralogical and geochemical signatures indicate that the ore-forming fluids were most probably originated from hydrothermal activities related to early-stage Emeishan Large Igneous Province (ELIP) subaqueous volcanism. Redox proxies reveal that sedimentary conditions evolved from euxinic-anoxic (footwall deposition), through anoxic-suboxic (Mn mineralization), to oxic (hanging-wall deposition). Such changes were probably resulted from a coeval eustatic sea-level drop and enhanced seawater oxygen supply. Manganese was likely initially enriched in form of Mn2+, and subsequently precipitated with oxidation, and then transformed into Mn carbonate during sediment diagenesis. To conclude, the tectono-hydrothermal activities and major environmental redox changes led by the ELIP volcanism have provided a favorable source-migration-sink system for the Mn mineralization. [ABSTRACT FROM AUTHOR]

The article presents a study to investigate the ZhuXi vanadium deposit from eastern Guizhou, China by using sedimentology, trace element geochemistry and isotope geochemistry. Topics discussed include carbon isotope value of vanadium, trace element geochemical characteristics of vanadium ore, and rare earth elements content in vanadium ore. Other topics discussed include distribution of vanadium ore in sandstone, siltstone, and silty mudstone.