Significance of δDkerogen, δ13Ckerogen and δ34Spyrite from several Permian/Triassic (P/Tr) sections

For the first time we report δD of kerogen (δDkerogen) for three Permian–Triassic (P–Tr) sequences (Hovea#3, Perth Basin, Western Australia; Jameson Land, East Greenland and Lusitaniadalen, Spitsbergen). We have compared δDkerogen with δ13C of kerogen (δ13Ckerogen) and δ34S of total reduced inorganic sulfur (TRIS, essentially pyrite; δ34Spyrite) of all the sections and for one sample set with δ13C of carbonate (δ13Ccarbonate) to establish (i) similarities between the sections and (ii) evaluate whether these signals are local and/or global. Stable isotope shifts occur for all three sample sets either at the P–Tr transition (Western Australia) or coinciding with the marine ecosystem collapse (Spitsbergen and East Greenland). δDkerogen reflects organic matter (OM)/ kerogen type and is not sensitive to the low level of thermal maturation. Reliable palaeoenvironmental information in terms of the use of δD can therefore only be obtained for the P–Tr transition from hydrogen compound-specific isotope analyses (CSIA) of biomarkers (Nabbefeld et al., 2010b). The negative shifts in δ13Ccarbonate (primary) and δ13Ckerogen are attributed to the release of 13C-depleted carbon into the atmosphere, whereas the isotopic excursions in δ34Spyrite relate to palaeoredox changes. However, the global coincidence in timing of the shifts in δDkerogen, δ34Spyrite and δ13Ckerogen suggests a relation between the sulfur, carbon and hydrogen cycles. The negative shifts in δ13Ccarbonate (primary) are in general attributed to the release of 13C-depleted source of carbon into the oceans and atmosphere, whereas δ13Ckerogen can reflect the latter in certain cases, but can also be superimposed by varying sources of OM/kerogen type. Isotopic excursions in δ34Spyrite relate to global changes in the palaeoredox conditions that affect sulfur cycling in the ancient seas.