The Ore-forming Age and Palaeoenvironment of the Mengyejing Formation in Jiangcheng, Yunnan Province

Research on the potash metallogenic epoch in the Mengyejing Formation is of important significance for the analysis of the corresponding relationships of the salt-bearing strata between Lanping-Simao Basin in Yunnan,Sakhon Nakhon Basin in Laos,and Khorat Basin in Thailand,and is also helpful to the prospecting for potassium deposits in Yunnan.However,there has long been controversial concerning the chronostratigraphy of this formation.Based on pollen analysis of samples collected from the Jiangcheng mining area,the authors defined the main sporopollen assemblage as Psophophaera-Exesipollenites-Classopollis assemblage,with the discovery of the index angiosperms pollen fossils like Monocolpopollenites and Tricopite,indicating an arid tropical and subtropical climate.Thus,the age of sporopollen assemblage in Mengyejing Formation should be between Aptian and Albian of late Early Cretaceous.