Late Permian global coal discontinuity and Permian-Triassic boundary ''events''

Voluminous Late Permian and Middle Triassic coal deposits occur throughout the ''Karoo'' basins of Gondwana. There is an abrupt and major worldwide coal hiatus at the Permian-Triassic (P-T-R) boundary. Evidence from a South African coalfield suggests that organic matter continued to accumulate in some of the sediments that straddle the P-T-R boundary, but that this organic matter was not preserved. At this time, Gondwana was subjected to accretion tectonics along the whole of its southern margin. This tectonism is considered to have caused regional uplift which affected vast areas in the heartland of Gondwana that were accumulating and burying organic matter. The timing of the uplift (similar to 250 Ma) approximately coincides with the minimum ages of the Late Permian coal formations, ''isotopic events'' in marine carbonates, major positive spikes in the Sr-81/Sr-86 isotope record of seawater, major global sea level regressions, the final amalgamation of Pangea along the Appalachian-Variscan mountain chain, and the most severe mass extinction of life recorded in the geologic record. Evidence from stable isotope measurements of Permian and Triassic freshwater coal and organic matter suggests that there was a decrease in the atmospheric C-13/C-12 ratio during the P-T-R transition time. The decrease in the ratio of atmospheric carbon is compatible with the input of negative delta(13)C values resulting from the oxidisation of solid organic carbon in the Karoo basins and possibly of oil and gas from the basins flanking the Appalachians-Variscides.