The Effects of Paleolatitude and Precipitation Gradients on Triassic Palynofloral Diversity

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Fowell 9418464 Climatic extremes have been suggested as the cause of high extinction rates among Late Triassic organisms, but the impact of warm global temperatures and climate change on the diversity of these fossil groups has not been examined in detail. Analysis of palynofloral data from continuous cores and correlative outcrops of the Triassic Newark Supergroup is proposed in order to separate the effects of paleolatitude, precipitation gradients, and evolutionary changes on palynofloral composition. The magnetic reversal stratigraphy and cyclostratigraphy of Newark basin cores provides a framework of rigorous temporal and geographic control for the Newark Supergroup and permits high-resolution correlation between separate but tectonically similar basins. Collection and comparison of coeval palynofloras from four time slices in cores of the Newark and Taylorsville basins and outcrops of the Culpeper and Fundy basins is planned in order to reconstruct Late Triassic palynofloral diversity gradients across 7o of paleoaltitude from an equatorial humid belt to a sub-equatorial arid zone. Species counts from these assemblages will be used to delineate Triassic vegetational communities, while similarity coefficients and polar ordination will be employed to determine how these communities changed over time and paleolatitude. Isolation of the climatic/geographic and temporal aspects of floral composition and diversity will permit evaluation of the various climate-driven extinction scenarios and provide a useful test of Triassic climate models.