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International audience; data detailed petrographic study of coal from the Mariovo basin in Macedonia suggests circulation of fluids mobilizing metals from different origins (basement, volcanism ?) during burial. Sulphur isotopic data on organic matter and pyrite indicate dominantly marine-derive fluids and processus of bacterial reduction of sulphates

International audience; The chemical structure of isolated chitinozoan specimens extracted from Early Silurian marine rocks has been investigated by micro-FTIR, laser micro-Raman spectroscopy and laser micropyrolysis-gas chromatography/mass spectrometry (LmPy- GC/MS). The samples were subjected to relatively low thermal stress as attested by several indices. LmPy-GC/MS and micro-FTIR indicate that chitinozoans consist mostly of a kerogen network dominated by aromatic groups with a low contribution of aliphatics and oxygen- or nitrogen-bearing compounds. No chitin-related product was found in the pyrolysate of the chitinozoans, confirming previous findings on the occurrence of this biopolymer in the fossil record.

International audience; For the past three years, we have been developing a procedure to measure carrier-free 129I/I in gram size quantities of marine sediments containing microgram quantities of iodine. Potential applications involve dating of old (>10 My) sediments and the detection of 129I (t1/2 = 15.7 My) from a purported supernova (SN) explosion not, vert, similar2.8 million years ago, that has been inferred from a 60Fe (t1/2 = 1.5 My) signal in a deep-sea ferromanganese crust [K. Knie, G. Korschinek, T. Faestermann, E.A. Dorfi, G. Rugel, A. Wallner, Phys. Rev. Lett. 93 (2004) 171103]. The procedure consists in washing the sediment with a NH2OH · HCl–HOAc mixture, extraction of iodine from the organic phase with TMAH, separation and purification using anion-exchange chromatography, and coprecipitation as AgI–Ag2O. We realized the washing step, which extracts authigenic iron and aluminum, could also be used to measure 60Fe/56Fe and 26Al/27Al in this phase of the same sediment sample. We outline here the chemical procedures developed, and briefly comment on their possible application to the supernova problem. We also point out a large discrepancy between the theoretically calculated 129I/127I ratio in pre-anthropogenic marine sediments, and that derived from experimental measurements.