Implications of the application of δ37Cl analysis to a new type of polyhalite potassium ore identified in northeast Sichuan, China

Abstract The discovery of a new type of polyhalite potassium ore in the Puguang area of northeast Sichuan Province is expected to alleviate the problem of insufficient potassium resources in China. However, in this high and steep fold belt, tectonic movement has made the sequence division of evaporites difficult; which, this division is an important factor in the study of the genesis of polyhalite. This study analyzed the effect of δ 37 Cl on the salt deformation structure throug h δ 37 Cl distribution in the halite from well CXD1 as an indicator to discussed the genetic mechanism of the new type of polyhalite potassium ore. The following conclusions are drawn: (1) Tectonic activity has a limited influence on the vertical direction of the two or multiple facies of primary sedimentary evaporite dominated by halite components in the plastic dynamic flow process, and the δ 37 C1 value can be used as a reference index in the study of the deformation of salt structures, except for local salt veins and salt in diapirs. (2) The δ 37 C1 values of halite from well CXD1 provide the latest quantitative geochemical data supporting the genetic model of the tectonic events and sedimentary environment influencing the new type of polyhalite potassium ore in the Puguang area of northeast Sichuan; the results indicate that the sedimentary environment featured a wide range of paleowater temperatures, extreme drought and frequent replenishment of marine water sources. (3) Additionally, the low evaporation stage of the Xuanhan area during the late Triassic (the sedimentary period of the fifth constituent of the Jialingjiang formation) about was not conducive to the deposition of soluble K-Mg salt.