Abstract
A palynostratigraphical investigation in the Buchenstein Group, the Wengen Group, the San Cassiano Formation and the Raibl Group of the western Dolomites has resulted in a palynological characterization of the Ladinian Stage and the Cordevolian Substage of the Karnian in the classic type-region for these units of Triassic chronostratigraphical subdivision. Seven characteristic phases in the compositional development of successive palynological assemblages can be recognized: the thiergartii—vicentinense phase (Upper Anisian, Illyrian Substage), the plurianulatus—novimundanus phase and the plurianulatus—secatus phase (Lower Ladinian, approximately Fassanian Substage), the secatus—dimorphus phase and the secatus—vigens phase (Upper Ladinian, approximately Longobardian Substage), the vigens—densus phase (Lower Karnian, Cordevolian Substage), and the densus maljawkinae phase (Middle Karnian, Julian Substage). A palynological concept of the Ladinian and Cordevolian is in reasonable agreement with the classic concepts of the units. Boundaries, however, do not coincide with lithostratigraphical boundaries. It remains difficult to correlate the palynological information with alternative concepts based on ammonoid zonation outside the type-region of the Ladinian. Palynostratigraphically it is unrealistic to consider the Cordevolian to be a synonym of the Julian. The results of quantitative analyses suggest arid climatic conditions. Local humid environments progressively increased during the Ladinian but gradually disappeared during the Cordevolian. These humid environments may explain the occurrence of southern (Gondwana) elements in the assemblages. The following new taxa and new combinations are formally introduced: Bocciaspora nov. gen., Sellaspora nov. gen., Gordonispora nov. gen., Lycopodiacidites kokenii nov. sp., Sellaspora rugoverrucata nov. sp., Sellaspora foveorugulata nov. sp., Krytomisporis ervii nov. sp., Bocciaspora blackstonensis (De Jersey) nov. comb., Gordonispora fossulata (Balme) nov. comb., Gordonispora lubrica (Orlowska-Zwolińska) nov. comb., Weylandites magmus (Bose et Kar) nov. comb., Partitisporites tenebrosus (Scheuring) nov. comb., Partitisporites maljawkinae (Klaus) nov. comb., and Partitisporites quadruplicis (Scheuring) nov. comb. The morphon concept is applied informally to unite morphologically closely related species within the group of the Circumpolles.
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