Deposition and genesis of the trona deposits in the Anpeng region,Henan

The Anpeng region,Henan abounds in trona resources.The present paper focuses on the deposition and accumulation,and genesis and processes of the trona deposits in the light of mud logs,well logs,cores,thin sections and sporopollen assemblages.The results of research show that trona mainly precipitated and crystallized in the arid and semi-arid climatic conditions,and occurs as the interbeds with(muddy) dolostones and/or the fillings in the pre-existing pores of dolostones.Two stages are recognized for the formation of trona: formation of sodium and alkaline reaction.It can be seen that the dolostone facies zone may be the favourable zone for the occurrence of trona deposits.