New biostratigraphic data on Anisian (Middle Triassic) palynomorphs from the Dolomites, Italy.

Abstract

This paper proposes an integrated Anisian palynomorph and ammonoid biostratigraphy, mostly based on data obtained from two successions (Monte Prà della Vacca and Dont) in the Dolomites belonging to the Dont Formation. In these sections, different pollen assemblages have been recognized. Assemblage A is marked by the presence of Aratrisporites reticulatus and Dyupetalum vicentinense; it occurs in the lower part of the Dont Formation and uppermost Gracilis Formation, but no ammonoid has been found in this stratigraphic segment. Thus, it is currently not possible to calibrate it with ammonoids. On the basis of tentative correlations with other ammonoids-bearing sections and data in the literature, it is correlated to the middle Pelsonian (Balatonicus Subzone p.p.). The assemblage has also been recognized in the Voltzia beds of Recoaro. Assemblage B occurs in the middle Dont Formation and is characterized by the first occurrence of Cristianisporites triangulatus. It contains ammonoids of the Balatonicus and Binodosus Subzones, of middle-late Pelsonian age. Assemblage C, marked by the first occurrence of “Kraeuselisporites” sp. 1 sensu Roghi, 1995a characterises the upper part of the Dont Formation, where ammonoids of the Abichi and Trinodosus Subzones indicate an Illyrian age