Palynological correlation of Carnian humid pulses throughout western Tethys

The Carnian Pluvial Event is an Upper Triassic swing toward increased rainfall best documented in the Tethys tropical belt, and mainly recognized on its effects on sedimentary systems, as the demise of carbonate platforms and the enhanced siliciclastic supply. In some portions of western Tethys, and particularly in the Raibler Schichten of the Northern Calcareous Alps and in the Dolomites, the Carnian Pluvial Event is recorded by four discrete siliciclastic pulses. In the Raibler Schichten, three siliciclastic intervals are documented and take the name of first, second and third shale. In order to correlate these pulses at the basinal scale, the study of the palynological assemblages in a section of the Raibler Schichten near Rubland (Austria), and of the classical succession of the Lunz nappe, have been carried out. More than eighty palynomorph species are recorded. Most of them correspond to typical Carnian morphospecies of the Carnian Pluvial Event in Europe. On the base of their stratigraphic distribution, three different palynomorph assemblages are described: Aulisporites astigmosus assemblage. Lagenella martinii assemblage and Granuloperculatipollis rudis assemblage. A fourth, older assemblage is also informally defined. A palynostratigraphic correlation between the NCA, the Germanic Basin and the Dolomites has been obtained. The four siliciclastic pulses recognized in the Raibler Schichten and Lunz are also found in the Dolomites, and yield the same palynological associations. The base of the Schilfsandstein, that record the Carnian Pluvial Event in the Germanic Basin, is correlated to the second or third siliciclastic pulse (first or second shale of the Raibler Schichten). Siliciclastic pulses are thus correlated throughout western Tethys, and can thus be interpreted as short-lived humid climate wiggles within the Carnian Pluvial Event. A quantitative analysis of the Carnian successions of the NCA highlights a shift toward hygrophytic elements in the uppermost Julian, and an abrupt return to xerophytic associations in the lower Tuvalian. The palynological hygrophytic associations that characterize the Aulisporites astigmosus and Lagenella martinii assemblages are present in many other parts of Europe and Middle East, suggesting that the Carnian Pluvial Event determined a humid climate perturbation in a wide area of the northern hemisphere spanning from tropical to high latitudes. (c) 2009 Elsevier B.V. All rights reserved.