Resumen de Evaporation stage of paleo-saline lake in North Shaanxi salt basin China: insight from fluid inclusions in halite
Fluid inclusions within halite from the Mizhi cores in the North Shaanxi Basin were studied to restore the ancient sedimentary environment, and to discuss the material supply on this basis. Fluid inclusion analyses include fluid inclusion petrography to examine their characteristics and types, hydrogen and oxygen isotopic compositions of trapped fluids, and package play flow components. This study shows that halite recrystallization occurred in the North Shaanxi Basin from fluid mixing of fresh and brine waters during transgressions. Hydrogen and oxygen isotopic compositions of halite inclusions show that precipitation of halite was supplied by multiple provenances, including thermal fluids. The study on the fluid compositions in the Ordovician halite inclusions indicates that the ancient sea water could allow the precipitation of the potassium magnesium salt rocks at that time, but the frequent transgressions influenced the preservation of the potassium magnesium salt rocks. Therefore, using the available data, this study proposes that the deposition of the MajiagouV member in the North Shaanxi Basin was supplied by transgressive sea water and thermal fluids. In addition, the frequent transgression during the Majiagou deposition affected the preservation of the potassium magnesium salt.
