Paleoenvironmental and carbon isotopic studies delta(13)C(org) from terrestrial and marine strata across the Permian-Triassic boundary in Antarctica and New Zealand

The Permian-Triassic boundary occurs at a major geologic transition, separating the Paleozoic from the Mesozoic era. This boundary marks both the largest extinction in Earth's history and the onset of a significant shift in stable carbon isotopes towards lighter values. This isotopic shift serves as a global chemostratigraphic marker that was utilized in this study to characterize Permian-Triassic boundary sections in Antarctica and New Zealand. The main focus of this dissertation is the analysis of changes in the terrestrial carbon cycle across the Permian-Triassic boundary, using stable carbon isotopes from paleosol organic matter (δ13C_org).; Fossil soils and associated strata were studied in three Permian-Triassic sections in Antarctica. An isotopic offset of 7‰ at Graphite Peak clearly marks the Permian-Triassic boundary and corresponds with the paleontologically defined boundary interval.; Results from detailed paleosol depth profiles of δ13C _org indicate similar trends as those found in modern soils. Combined with grain size distribution and trends from bulk rock geochemistry it was possible to identify a variety of paleosols, including Entisols, Inceptisols, Alfisols, and Histosols. An exception to this trend was found in Early Triassic paleosols with anomalous δ13C_org values (as low as −42‰) in the subsurface (B) horizon. This suggests a possible contribution of methane to an Early Triassic greenhouse atmosphere.; To further characterize paleoenvironmental and paleoclimatic conditions in high latitudinal, peat-forming environments, individual Histosols from Antarctica were studied in detail. The results allowed for distinction between paleoenvironments with discontinuous permafrost and temperate, permafrost-free conditions.; Carbon isotopic analysis of a marine Permian-Triassic section in New Zealand revealed a significant isotopic offset of −8‰, allowing more precise location of the Permian-Triassic boundary. Early Triassic isotopic values as low as −37‰ provide additional isotopic support for a potential methane release in the Early Triassic. This hypothesis adds an alternative mechanism for the Permian-Triassic extinction in addition to oceanic anoxia, volcanic eruption, and bolide impact. The source and trigger of this methane release remains to be identified.; This dissertation includes both my previously published and my co-authored materials.