Search

The Lower Permian Fengcheng Formation in the Mahu Sag of the Junggar Basin was developed in a volcanic-induced alkaline saline lacustrine environment, with deposition of thick-bedded sodium carbonates and high-quality source rocks, as well as the borosilicate reedmergnerite, which is a rare mineral globally but is very rich in the Fengcheng Formation. Based on petrography, fluid inclusion and boron isotope studies, the aim of this study was to discover the origin of the reedmergnerite which, in the Fengcheng Formation, often replaces carbonate minerals, including shortite, eitelite, northupite, calcite, trona, and even barytocalcite. The homogenization temperature of the primary inclusions in the reedmergnerite ranged from 100 to 116°C. Previous synthetic experimental studies have found that the δ11B values of reedmergnerite are 0.33-2.13‰. It is proposed here that, due to the limitations of temperature and pressure in surface or shallow burial processes, the source of boron in reedmergnerite was deep hydrothermal fluid in the original sedimentary environment, mainly in deep diagenetic environments (>3000 m). Therefore, the enrichment of reedmergnerite in the Fengcheng Formation is interpreted as the result of intense magmatic hydrothermal activity and a long diagenetic history. [ABSTRACT FROM AUTHOR]

Because the boron (B) concentration in water has an apparent positive correlation with salinity, the B content adsorbed in sediments is often regarded as an important indicator to reconstruct the water salinity in a sedimentary environment. The premise of the quantitative reconstruction of paleosalinity is that the B uptake in sediments is proportional to the B concentration in water; however, the study showed that there is no direct relationship. The B absorption in sediments can be affected by both the content of the clay minerals and the total organic carbon content. The data from testing modern sediments and water samples in the Qinghai Lake show that a higher content in clay minerals is beneficial for B adsorption. Furthermore, the organic carbon from halophiles has a strong effect on the enrichment of B. Therefore, the organic carbon content in sediments should be considered when the paleosalinity of water is reconstructed using its B content. It is also thought that the Adams and Couch formulas are not suitable for reconstructing the salinity of water with a high organic carbon content in sediments because they consider only the effect of clay minerals on the adsorbed B without the contribution of organic carbon. [ABSTRACT FROM AUTHOR]

The article discusses the fluid inclusion study of diversity minerals and geological significance Xihuashan Tungsten Deposit, Jiangxi Province, China. Topics discussed include classification of fluid inclusions into three types, microthermometric analysis of fluid inclusions and study of wolframite and cassiterite reflecting ore genesis.