LAUSR

Abstract Palynological study of the Upper Triassic Bidestan and Howz-e-Sheikh members of the Nayband Formation of the Tabas Block, Central Iran, revealed relatively diverse and well-preserved assemblages of palynoflora dominated by dinoflagellate cysts and miospores. The two well-known interval dinoflagellate cysts zones of Hebecysta balmei Interval Zone and Rhaetogonyaulax rhaetica Interval Zone were differentiated based on the index dinoflagellate cysts recorded and confirmed the middle Norian-Rhaetian age for the members. The palynological content of these dinoflagellate cyst zones are quite comparable to the Upper Triassic zones of Australia. Biogeographically, the recorded palynomorphs are a mixture of both Eurasian and Gondwanan elements but the middle Norian to earliest Rhaetian elements are more closely related to Gondwanic flora. The co-occurrence of marine and terrestrial elements suggests a shallow marine environment for the members studied.