Influence of non-marine fluid inputs on potash deposits in northeastern Thailand: evidence from δ37Cl value and Br/Cl ratio of halite

Abstract

Late Cretaceous evaporite in the Khorat Plateau (KP) is one of the largest potash deposits in the world. Previous researches reported that the origin of potash deposits in the KP is controversial; however, recent studies emphasized non-marine fluids (hydrothermal fluid or meteoric water) influenced geochemical behaviors of potash deposits. Eleven halite samples from halite and potash layers in a drilling core (NS007) in southwestern KP were collected and analyzed for δ37Cl values, Br− and Cl− concentrations in this study. The results show that (1) low δ37Cl values (− 1.31‰ ~ + 0.14‰) of halite from halite layer, combining with reported isotopic (δD and δ18O) values of fluid inclusions in halite in corresponding layer, suggest possible influence of hydrothermal fluid; (2) positive correlation between δ37Cl values and Br × 103/Cl ratios, high δ37Cl values (− 0.48‰ ~ + 0.41‰) and previous high 87Sr/86Sr values of halite from potash layer indicate meteoric water inputs into this layer. These comparisons demonstrate that hydrothermal or meteoric waters (non-marine fluids) influenced potash deposits in northeastern Thailand.