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During the Ediacaran–Cambrian transition, a series of stratal continuous and well-preserved siliceous rock and phosphorite assemblages developed in Qingzhen, Guizhou Province, China, facilitating research on the biological evolution, marine chemistry, and palaeoecological environment of this period. Therefore, we investigated the paleontology, trace and rare earth elements, total organic carbon, total sulfur content, and Zn isotopes of the phosphorus-bearing rock series in the Taozichong Formation of the Cambrian period in Qingzhen. Geochemical analysis reveals that the sedimentary rocks in this area were formed in the oxygen-rich seawater environment and were not affected by high-temperature hydrothermal activity. The upwelling ocean current provided abundant rare earth elements and other nutrient elements, as well as conditions for the prosperity of biota in Qingzhen. In addition, the δ66Zn value (−0.21‰–0.41‰ range and 0.17‰ mean) in the Qingzhen phosphorous rock series was much lower than that in seawater, indicating a strong level of biological productivity. The variation trend of δ13C, δ18O, and δ66Zn exhibited four stages and three obvious drift events. The results suggest that climate change during this period led to the intermittent flourishing and extinction of organisms, which triggered the negative drift of δ13C and δ18O in the ocean, resulting in a coordinated response of δ66Zn. The unique ecological environment of the Taozichong Formation in Qingzhen also provides favorable conditions for the population continuation of Ediacaran-type benthic soft-bodied metazoon dominated by discoid fossils, Shaanxilithes, worm fossils, and sponge fossils in the Cambrian strata, as well as participation in the global biological explosion events. The study area provides new insights for rebuilding the global Ediacaran–Cambrian ecosystem during the transition period. [ABSTRACT FROM AUTHOR]

Iodine was relatively enriched in the sedimentary phosphorite that formed during the Doushantuo period of Late Ediacaran, South China, especially in the Central of Guizhou Province, Southwest China. The resources of the associated iodine in the phosphorite are extremely high. The analysis and test of elements such as iodine in the phosphorus-bearing rock series reveal that iodine occurs only in the phosphorite and the iodine has positive correlation with PO and CaO which are the main components of apatite, while has negative correlation with major oxides including MgO, NaO, FeO, TiO and KO, which showed that the iodine is mainly rich in phosphorite. Meanwhile, it was observed that the iodine content is the highest in the gray-white clastic phosphorite, but is relatively low in the gray-black carbonaceous phosphorite. Discussion of the sedimentary environment in the research area showed that the gray, gray-white nest-like, particle-like, and fragmental algae-enriched phosphorite feature the most abundant iodine element, with the average content of 59 mg kg and the maximum value of 98 mg kg. The compacted blocky phosphorite deposited in the neritic marine basin facies only has trace iodine, maybe due to the impact on the iodine absorption caused by the inhibition of algae propagation under anaerobic and reduction conditions. Results of correlation analysis illustrate that the relationship between iodine and the number of algae was suggested. Based on the aforementioned regulations and conditions for the iodine concentration in the phosphorite of the Late Edicanran Doushantuoian, the main iodine-enriched of ore, ore type, and facies belt were considered biogenic apatite, clastic phosphorite, and neritic marine platform facies, respectively. [ABSTRACT FROM AUTHOR]

The article focuses on a study that investigates geochemistry characteristics of Nibao super large gold deposits from Guizhou Province, China and its geologic significance. The study reveals that hydrothermal precipitation prompted the initial formation of Nibao gold deposits and subsequent low-temperature hydrothermal processes resulted in gold remobilization in ore-forming materials. Also the study shows that the Nibao gold deposits have sedimentary hydrothermal alteration characteristics.