RECONSTRUCTING KUNGURIAN (CISURALIAN, PERMIAN) TERRESTRIAL ENVIRONMENTS WITHIN A MEGACALDERA IN THE SOUTHERN ALPS (N-ITALY) USING LITHOFACIES ANALYSIS, PALYNOLOGY AND STABLE CARBON ISOTOPES

摘要

During the Permian, climate experienced a change from icehouse to greenhouse conditions. Few multidisciplinary studies have investigated Kungurian (late Cisuralian) tropical terrestrial ecosystem and climate changes. Here, we apply an interdisciplinary approach to two alluvial-lacustrine successions of the Athesian Volcanic Group (Southern Alps, northern Italy) deposited in a Kungurian megacaldera during periods of volcanic quiescence. Sedimentological analysis combined with palynofacies studies allowed the reconstruction of the depositional envi-ronments. The study of sporomorph assemblages and stable organic carbon isotopes provided information on plant communities and the climate context. Two different depositional environments were present in the megacaldera: one proximal and one more distal with respect to the source, distinguished by a slightly different composition of the sedi-ments, palynofacies and organic carbon isotopes. The plant community in the area was dominated by xeromorphic-hygromorphic taxa. The delta 13Corgvalues are comparable to those of other Cisuralian continental organic matter and plants. The stable carbon isotope values show a small variability, which correlates weakly, but significantly, with the abundance of xeromorphic elements. All observations support deposition during semiarid to arid climate conditions, typical of the mid-late Cisuralian in the area.