HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

No abstract

In this study, an integrated approach was applied using available sedimentary, geochronology, geochemical and isotopic datasets to better understand the complex interactions between production, destruction, and dilution processes that characterize the organic-rich sediments dynamic across the K-T boundary in a lacustrine system. This approach was tested here on the Late Cretaceous to Early Cenozoic Yacoraite Formation, a typical lacustrine source rock from the Salta rift Basin (NW Argentina). The Yacoraite Formation corresponds to a mixed carbonate-siliciclastic lacustrine sedimentary system, deposited during the sag phase (post-rift). We demonstrated here that new ashes U-Pb dating tie the K-T boundary during the deposition of the Yacoraite Formation.The Yacoraite Formation recorded major climate changes that can be documented in terms of catchment dynamic, erosion processes, carbonate accumulation trends, lacustrine dynamic and source rock quality. The pattern of organic carbon enrichment in the Yacoraite Formation illustrates how a biological pump came across a major climatic change. The background organic matter correspond to Type I dominated by algal growth (mean HI 600-800 mgHC/gTOC, TOC 0 1-2 wt.%). The K-T boundary was the climax of a climate change initiated ca. 0.3 Myr before and induced a major change in the catchment weathering processes, which temporally corresponds to the accumulation of poor quality source rock intervals (TOC 0 ≤ 0.2 wt.% and HI < 50 mgHC/gTOC) in these series. The K-T boundary is highlighted by the main negative anomaly in δ 13 C of the carbonate deposits of the Yacoraite Formation. It was followed by a major pulse in paleoproductivity, itself followed by a major pulse in TOC 0 (10-15 wt.%) under anoxia conditions. In ca. 0.2 Myr the lacustrine dynamic and its related organic-carbon enrichment resumed to their initial setting, just prior to the preluding K-T boundary climate change. Results suggest that the Yacoraite Formation can be considered as a world-class example to illustrate how the K-T boundary is recorded in lacustrine sediments.

No abstract

-Unconventional resources such as tight, fractured and hybrid shale gas and oil plays as well as oil or kerogen shale systems, are considered exploitable self-contained source and reservoir rocks. A better understanding of the thermal cracking of sedimentary organic matter, hydrocarbons generation, expulsion, storage and retention mechanisms constitutes a key point, estimating the oil and gas in-place, free or adsorbed, for their exploration and exploitation. Herein, we introduce a new "ready to use" method of analysis and interpretation for the Rock-Eval 6 device for better assessment of free or sorbed hydrocarbons in unconventional shale plays. This method was developed at IFP Energies nouvelles (France) and was tested on 15 actual or potential unconventional shale samples from Silurian Shale (Algeria), Mississippian Barnett Shale (USA), Early Jurassic Shale (France), Late Jurassic Bazhenov Shale (Russia) and Eocene Green River Shale at different thermal maturity stages. Results indicate a better quantification of free and/or sorbed hydrocarbons (Sh0 and Sh1 peaks) as well as a more accurate determination of the RockEval T max maturity parameter.Résumé -Nouvelle méthode de pyrolyse Rock-Eval pour la caractérisation des hydrocarbures de roches mères non conventionnels -Les ressources non conventionnelles, en particulier les hydrocarbures de roches mères et les schistes bitumineux sont actuellement considérées comme des roches réservoirs pétroliers exploitables. Une meilleure compréhension sur le craquage thermique de la matière organique sédimentaire, sur les mécanismes de production/génération, d'expulsion, de stockage et de rétention des hydrocarbures constitue un point essentiel à la fois pour l'estimation mais également pour l'exploration et l'estimation du pétrole et du gaz en place (libre ou adsorbé) présents dans ces systèmes. Ici, nous présentons une nouvelle méthode d'analyse et d'interprétation pour le Rock-Eval 6 permettant une meilleure estimation/évaluation des hydrocarbures libres ou adsorbés au sein d'une roche mère non conventionnelle. Cette méthode, développée à l'IFP Energies nouvelles (France), a été élaborée et testée sur 15 échantillons de schistes actuels ou potentiels provenant : du Silurien Shale (Algérie), du Mississippien Barnett Shale (USA), du Jurassique Inférieur du Bassin de Paris (France), du Jurassique Supérieur Bazhenov Shale (Russie) et de l'Eocène Green River Shale (USA) et ce, à des stades différents de maturité thermique. Les résultats