Mechanisms of biogenic gas migration revealed by seep carbonate paragenesis, Panoche Hills, California

A comprehensive study of seep carbonates at the top of the organic-rich Maastrichtian to Danian Moreno Formation in the Panoche Hills (California) reveals the mechanisms of generation, expulsion, and migration of biogenic methane that fed the seeps. Two selected outcrops show that seep carbonates developed at the tip of sand dykes intrude up into the Moreno Formation from deeper sandbodies. Precipitation of methane-derived cements occurred in a succession of up to 10 repeated elementary sequences, each starting with a corrosion surface followed by dendritic carbonates, botryoidal aragonite, aragonite fans, and finally laminated micrite. Each element of the sequence reflects three stages. First, a sudden methane pulse extended up into the oxic zone of the sediments, leading to aerobic oxidation of methane and carbonate dissolution. Second, after consumption of the oxygen, anaerobic oxidation of methane coupled with sulfate reduction triggered carbonate precipitation. Third, progressive diminishment of the methane seepage led to the deepening of the reaction front in the sediment and the lowering of precipitation rates. Carbonate isotopes, with δ¹³C as low as −51‰ Peedee belemnite, indicate a biogenic origin for the methane, whereas a one-dimensional basin model suggests that the Moreno Formation was in optimal thermal conditions for bacterial methane generation at the time of seep carbonate precipitation. Methane pulses are interpreted to reflect drainage by successive episodes of sand injection into the gas-generating shale of the Moreno Formation. The seep carbonates of the Panoche Hills can thus be viewed as a record of methane production from a biogenic source rock by multiphase hydraulic fracturing

La perméabilité des failles polygonales déduite de la géométrie de leurs intersections avec des cheminées linéaires : une étude de cas dans le bassin du Bas-Congo

Layer-bound arrays of polygonal compaction faults have long been considered as important migration routes for hydrocarbon fluids leaking to the surface across thick shale sequences. A classic example is the deep offshore of the Lower Congo Basin where numerous fluid-venting structures are present above a Pliocene polygonal fault system. In this paper we present a detailed seismic analysis of a newly recognised system of Quaternary-aged Linear Chimneys and their intersection geometries with pre-existing Pliocene-aged polygonal faults (PF). Most (73%) of the 209 chimneys analysed intersect the lower portions of polygonal faults and almost half of these are rooted in strata below the PF interval. This indicates that fluid (in this case gas) migrated vertically, cross-cutting polygonal faults as it ascended through the tier. This is a strong indicator that PFs did not provide viable migration pathways otherwise chimneys would terminate at the upper tip of the fault, which would be the most likely migration exit point. Only twice in the whole system of Linear Venting Systems did this occur. A sub-set of chimneys stems from or above PF planes but these are restricted to either the lower footwall or from the apex area of hanging wall. At best they are evidence of fluids migrating up the lower part of polygonal faults and exiting deep within the tier, then migrating through most of the tier in their own vertical leakage vents. These results provide strong indicators that at least within this part of the Lower Congo Basin polygonal faults were the least effective/favoured migration pathway and that it was more energy-efficient for migrating gas to hydrofracture its fine-grained overburden than to re-open polygonal faultsLes réseaux de "failles polygonales" (failles de compaction restreintes à un intervalle stratigraphique) ont été longtemps considérés comme d'importants chemins pour la migration vers la surface des hydrocarbures à travers d'épaisses séries argileuses. Un exemple classique est fourni par l'offshore profond du bassin du Bas-Congo où de nombreuses structures d'échappement de fluides sont présentes au-dessus d'un système de failles polygonales affectant l'intervalle pliocène. Ce papier présente l'analyse sismique détaillée d'un système récemment reconnu de cheminées linéaires d'âge quaternaire, ainsi que de la géométrie de leurs intersections avec des failles polygonales pliocènes (donc préexistantes). La plupart (73 %) des 209 cheminées analysées recoupent le mur des failles polygonales, et près de la moitié d'entre elles s'enracinent dans l'intervalle sous-jacent à l'intervalle faillé. Cette disposition indique que le fluide (gaz en l'occurrence) a migré verticalement, recoupant les failles polygonales lors de sa remontée ; elle met également en lumière le fait que les failles polygonales ne constituent pas un chemin de migration efficace, sans quoi les cheminées se termineraient à l'extrémité supérieure de la faille, qui serait le point de fuite préférentiel. Cette configuration n'a été observée que dans deux cas sur l'ensemble du système. Un sous-ensemble de cheminées se développent depuis la partie inférieure des plans de failles polygonales ou directement à l'apex des grabens. Au mieux ces cheminées sont l'expression de fluides ayant migré seulement le long de la partie inférieure des failles polygonales avant de s'en échapper pour migrer verticalement le long d'un chemin créé par le gaz lui-même. Ces résultats indiquent de façon nette que, dans cette partie du bassin du Bas-Congo au moins, les failles polygonales ne constituent pas un chemin de migration et qu'il est énergétiquement plus efficace pour le gaz de migrer par fracturation hydraulique de la couverture argileuse que de rouvrir les failles préexistantes

Neonatal infections with multidrug-resistant ESBL-producing E. cloacae and K. pneumoniae in Neonatal Units of two different Hospitals in Antananarivo, Madagascar

Background: We investigated the molecular mechanism of ß-lactam resistance in extended-spectrum ß-lactamase (ESBL)-producing Enterobacterial strains isolated in neonatal units of different hospitals in Anatnanarivo, Madagascar.Methods: Bacteria were identified by standard biochemical methods, disc diffusion antibiograms and Etest. Resistance genes were sought by PCR. Strains were characterized by Rep- PCR (Diversilab), plasmid analysis and rep-typing.Results: From April 2012 to March 2013, 29 ESBL-producing E. cloacae and 15 K. pneumoniae were isolated from blood culture (n = 32) or gastric samples (n = 12) performed at day 0 or 2 from 39/303 newborns suspected of early neonatal infection. These infants were treated with expanded spectrum cephalosporins, due to lack of carbapenems, leading to a high mortality rate (45 %). Isolates recovered were all, but 4, multidrug resistant, particularly to fluoroquinolones (FQ) except for 21 E. cloacae isolates. Isolates produced TEM-1 and CTX-M-15 ß-lactamases and their genes were located on several self- transferable plasmids of variable sizes sizes that could not be linked to a major plasmid incompatibility group. E. cloacae isolates belonged to 6 Rep-types among which two counted for 11 isolates each. The FQ resistant E. cloacae isolates belonged to one clone, whereas the FQ susceptible E. cloacae isolates belonged to four clones. The K. pneumoniae isolates belonged to 9 Rep-types among which one included five isolates.Conclusion: This study is the first molecular characterization of ESBL- producing isolates from neonatology units in Madagascar, a country with limited epidemiological data. It revealed an important multi-clonal dissemination of CTX-M-15- producing isolates reflecting both the high community carriage and the very early nosocomial contamination of the neonates

Neonatal infections with multidrug-resistant ESBL-producing E. cloacae and K. pneumoniae in Neonatal Units of two different Hospitals in Antananarivo, Madagascar

Background: We investigated the molecular mechanism of ß-lactam resistance in extended-spectrum ß-lactamase (ESBL)-producing Enterobacterial strains isolated in neonatal units of different hospitals in Anatnanarivo, Madagascar.Methods: Bacteria were identified by standard biochemical methods, disc diffusion antibiograms and Etest. Resistance genes were sought by PCR. Strains were characterized by Rep- PCR (Diversilab), plasmid analysis and rep-typing.Results: From April 2012 to March 2013, 29 ESBL-producing E. cloacae and 15 K. pneumoniae were isolated from blood culture (n = 32) or gastric samples (n = 12) performed at day 0 or 2 from 39/303 newborns suspected of early neonatal infection. These infants were treated with expanded spectrum cephalosporins, due to lack of carbapenems, leading to a high mortality rate (45 %). Isolates recovered were all, but 4, multidrug resistant, particularly to fluoroquinolones (FQ) except for 21 E. cloacae isolates. Isolates produced TEM-1 and CTX-M-15 ß-lactamases and their genes were located on several self- transferable plasmids of variable sizes sizes that could not be linked to a major plasmid incompatibility group. E. cloacae isolates belonged to 6 Rep-types among which two counted for 11 isolates each. The FQ resistant E. cloacae isolates belonged to one clone, whereas the FQ susceptible E. cloacae isolates belonged to four clones. The K. pneumoniae isolates belonged to 9 Rep-types among which one included five isolates.Conclusion: This study is the first molecular characterization of ESBL- producing isolates from neonatology units in Madagascar, a country with limited epidemiological data. It revealed an important multi-clonal dissemination of CTX-M-15- producing isolates reflecting both the high community carriage and the very early nosocomial contamination of the neonates

Downslope-shifting pockmarks: interplay between hydrocarbon leakage, sedimentations, currents and slope’s topography

Pockmarks in Pliocene-Quaternary continental slope deposits offshore Angola show features related to: (1) fluid leakage craters that formed repeatedly, (2) authigenic methane-derived carbonates that indicate the (former) presence of hydrocarbons and (3) erosional–depositional structures that are clearly related to current activity. Depending on topography, the pockmarks show differing development: “Advancing Pockmarks” preferentially developed on regional slopes or inclined topography (>  2.5°–3°). They arranged in a chain-like pattern and mimic the outline of buried turbidite channels below. These pockmarks and their infill migrated downslope in response to shifting vents. “Nested Pockmarks” occur in gently sloping areas (< 2°). Their isolated conical infill records slope-parallel migration within a specific depth range pointing to the influence of contour currents. Both pockmark types are long- lived and they record preferential fluid migration along specific pathways, which developed at the downcurrent sidewalls of pockmarks due to flow separation initiating “cavity flow” within the pockmarks. The durable specific migration paths include pockmark sidewalls, vertically stacked erosional-interface of sediment waves, or entire pockmark bodies. The vertical extent of both pockmark types from End Miocene to the present-day seafloor documents various intensities of episodic fluid bursts followed by periods of quiescence and fill

SARGOS: Securing Offshore Infrastructures Through a Global Alert and Graded Response System

International audienceThe purpose of the project SARGOS is to develop a global alert and graded response system to answer the recent but strong need for securing critical civilian offshore infrastructures, vulnerable to piracy or terrorist actions from the sea. The challenge of protecting these infrastructures against malevolent intrusions requires to develop innovative strategies so as to ensure in a coordinate way the whole processing line: automatic surveillance, robust detection, continuous adjustment of the reaction plan and graded implementation of the relevant set of reactions. The system handles : Automatic and robust detection and classification of small size maritime targets in rough sea; Detection of suspicious behaviors in a security zone around the platform; Formalization and modeling of graded internal and external reactions, adapted to the dangerousness of the detected intrusion and taking into account security rules in force on the platform, geopolitical environment and legal aspects; Activation of progressive and reversible reactions, according to an intelligent situation analysis process. Reactions can go from a simple alert up to bringing non lethal reaction means into play. The project will materialize with the implementation of all the processing line in a single platform that will be used to carry out experimentations and to validate the overcoming of critical issues and the appropriateness of the proposed concept with regards to users' needs. SARGOS has been selected by the French Nationa

DNAM-1 and PVR Regulate Monocyte Migration through Endothelial Junctions

DNAX accessory molecule 1 (DNAM-1; CD226) is a transmembrane glycoprotein involved in T cell and natural killer (NK) cell cytotoxicity. We demonstrated recently that DNAM-1 triggers NK cell–mediated killing of tumor cells upon engagement by its two ligands, poliovirus receptor (PVR; CD155) and Nectin-2 (CD112). In the present paper, we show that PVR and Nectin-2 are expressed at cell junctions on primary vascular endothelial cells. Moreover, the specific binding of a soluble DNAM-1–Fc molecule was detected at endothelial junctions. This binding was almost completely abrogated by anti-PVR monoclonal antibodies (mAbs), but not modified by anti–Nectin-2 mAbs, which demonstrates that PVR is the major DNAM-1 ligand on endothelial cells. Because DNAM-1 is highly expressed on leukocytes, we investigated the role of the DNAM-1–PVR interaction during the monocyte transendothelial migration process. In vitro, both anti–DNAM-1 and anti-PVR mAbs strongly blocked the transmigration of monocytes through the endothelium. Moreover, after anti–DNAM-1 or anti-PVR mAb treatment, monocytes were arrested at the apical surface of the endothelium over intercellular junctions, which strongly suggests that the DNAM-1–PVR interaction occurs during the diapedesis step. Altogether, our results demonstrate that DNAM-1 regulates monocyte extravasation via its interaction with PVR expressed at endothelial junctions on normal cells

SARGOS : Système d'Alerte et Réponse Graduée Off Shore

National audienceLes champs de production d'hydrocarbures deviennent de plus en plus une cible de choix pour la piraterie maritime voire la menace terroriste. Or si les plates-formes et navires associés forment un réseau industriellement abouti en ce qui concerne l'exploitation, ils sont démunis face aux actes de malveillance intentionnels : de ce point de vue, ce sont des cibles isolées et exposées. Le projet SARGOS vise à répondre à l'émergence du besoin de sûreté des infrastructures offshore civiles vulnérables aux actions de malveillance, de piraterie ou de terrorisme menées à partir de la mer. Il propose le développement d'un système assurant de manière coordonnée la chaîne globale de protection : veille et surveillance automatisées ; détection d'intrusion ; évaluation de dangerosité ; plan de réaction gradué et piloté en temps réel pour rester constamment adapté au niveau de menace représenté par l'intrusion détectée. Une des capacités clefs est l'élaboration d'une stratégie complète et mutualisée de défense, incluant la mise en sûreté des personnes, la diffusion de l'alarme, la coordination des moyens d'assistance extérieure et la mise en oeuvre de moyens de dissuasion non létaux. Un enjeu fort est mis sur la prise en compte des modes de fonctionnement de l'infrastructure et des contraintes règlementaires et juridiques. SARGOS apporte une réponse nouvelle et innovante dans ce domaine de la sûreté maritime pour lequel il n'existe pas aujourd'hui de système opérationnel. Après un rappel de la problématique, cet article fait le point sur les différentes approches innovantes mises en oeuvre dans le développement du projet

"SARGOS" : Système d'Alerte et Réponse Graduée Off Shore

International audienceLe projet SARGOS répond à l'émergence du besoin de sûreté des infrastructures offshore civiles vulnérables aux actes de malveillance, de piraterie ou de terrorisme menées à partir de la mer. Il propose le développement d'un système assurant de manière coordonnée la chaîne globale de protection : veille et surveillance automatisées ; détection d'intrusion ; évaluation de dangerosité ; plan de réaction gradué et piloté en temps réel pour rester constamment adapté au niveau de menace représenté par l'intrusion détectée. Une des capacités clefs est l'élaboration d'une stratégie complète et mutualisée de défense, incluant la mise en sûreté des personnes, la diffusion de l'alarme, la coordination des moyens d'assistance extérieure et la mise en oeuvre de moyens de dissuasion non létaux pour apporter une réponse complète à la menace. Un démonstrateur du système SARGOS illustrant toute la chaîne de protection a été déployé sur site pour des expérimentations en vraie grandeur selon des scénarios définis avec les opérationnels. Les essais ont permis de valider tous les points clefs : détection de petites embarcations - levée d'alertes pertinentes couplant analyse de comportement des embarcations et évaluation de dangerosité - Assistance intuitive à l'opérateur pour l'activation de procédures de réaction proposées en dynamique suivant une logique prédéfinie propre aux moyens disponibles