Seabeam and seismic reflection imaging of the tectonic regime of the Andean continental margin off Peru (4°S to 10°S)

Suite à une campagne géophysique réalisée au large de la côte du Perou (croisière Seaperc du R/V "Jean Charcot", juillet 1986), les auteurs proposent une nouvelle interprétation des structures caractérisant la pente continentale de la région étudiée. D'autre part, ils considèrent que cette marge active est une marge active en extension ou bien une marge d'effondrement qui développe un complexe d'accrétion induit par les effondrements de la partie médiane de la pente

Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise

Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 107 (2010): 14020-14025, doi:10.1073/pnas.1009205107.Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultra-slow spreading ridges which were the last to be demonstrated to host high-temperature venting, but may host systems particularly relevant to pre-biotic chemistry and the origins of life. Here we report first evidence for diverse and very deep hydrothermal vents along the ~110 km long, ultra-slow spreading Mid-Cayman Rise. Our data indicate that the Mid- Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultra-mafic systems and, at ~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent-types identified here and their relative geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic organic chemical synthesis and extremophile microorganisms; and unparalleled faunal biodiversity - all in close proximity.This research was funded through NASA (ASTEP) and WHOI (Ocean Ridge Initiative)

The effects of long-term saturated fat enriched diets on the brain lipidome

The brain is highly enriched in lipids, where they influence neurotransmission, synaptic plasticity and inflammation. Non-pathological modulation of the brain lipidome has not been previously reported and few studies have investigated the interplay between plasma lipid homeostasis relative to cerebral lipids. This study explored whether changes in plasma lipids induced by chronic consumption of a well-tolerated diet enriched in saturated fatty acids (SFA) was associated with parallel changes in cerebral lipid homeostasis. Male C57Bl/6 mice were fed regular chow or the SFA diet for six months. Plasma, hippocampus (HPF) and cerebral cortex (CTX) lipids were analysed by LC-ESI-MS/MS. A total of 348 lipid species were determined, comprising 25 lipid classes. The general abundance of HPF and CTX lipids was comparable in SFA fed mice versus controls, despite substantial differences in plasma lipid-class abundance. However, significant differences in 50 specific lipid species were identified as a consequence of SFA treatment, restricted to phosphatidylcholine (PC), phosphatidylethanolamine (PE), alkyl-PC, alkenyl-PC, alkyl-PE, alkenyl-PE, cholesterol ester (CE), diacylglycerol (DG), phosphatidylinositol (PI) and phosphatidylserine (PS) classes. Partial least squares regression of the HPF/CTX lipidome versus plasma lipidome revealed the plasma lipidome could account for a substantial proportion of variation. The findings demonstrate that cerebral abundance of specific lipid species is strongly associated with plasma lipid homeostasis

Campagne Seacarib 2: Decrochements et frontieres de plaques dans les Caraibes

In November/December 1987, the R/V Jean-Charcot conducted geophysical surveys (Seabeam bathymetry, single-channel seismic reflection, gravimetry and magnetism) along the northern caribbean boundary, between Cuba, Haiti and Jamaica (Pointe-a-Pitre/Santiago de Cuba/Fort-de-France). During that cruise, we focused our attention on the following themes: the transition between typical oceanic crust and thinned continental crust associated with early rifting; the structures associated with the Oriente (Bartlett) Transform Fault south of Cuba; and the eastward continuation of the Oriente Fault north of Hispaniola

A Natural Model of Active Transpressional Tectonics the en Échelon Structures of the Oriente Deep, Along the Northern Caribbean Transcurrent Plate Boundary (Southern Cuban Margin) Un modèle naturel de tectonique transpressive active Les structures en échelon de la fosse de l'Oriente le long de la limite de plaques décrochante Nord-Caraïbe

A seabearn and seismic reflection structural study of the Oriente Deep, located along the northern Caribbean transcurrent plate boundary, allows us to image in three dimensions active transpressional structures (cruise SEA-CARIB II, R/V Jean Charcot). These structures are folds and reverse faults. The folds display an en échelon arrangement and are set within three E-W trending alignments. The folds appear with an axis trending 30° to 40° to the shear direction. Their axes have undergone a rotation which gives them in plan a sigmoidal Zshape. The reverse faults formed after the folds and are located at the bases of the anticlines. The folding occurs outside the main strike-slip fault, above inactive burried faults affecting the basement of the Oriente Deep. The Oriente Deep is a exceptional natural model for the study of active transpressional deformation along a major strike-slip fault. <br> La campagne océanographique SEACARIB II du N/O Jean Charcot a permis l'étude structurale du bassin de l'Oriente, situé le long de la limite de plaques décrochante nord caraïbe au sud de Cuba. Cette étude, par Seabeam et sismique réflexion, y a révélé des structures transpressives actives (plis et failles inverses) et a permis de les illustrer en trois dimensions. Au sein de ce bassin, les plis sont disposés en échelon en trois alignements E-W. La direction de l'axe des plis naissant fait un angle de 30° à 40° avec la direction du décrochement principal. Les axes des plis subissent ensuite une rotation qui leur donne, en carte, une forme sigmoïdale en Z . Des failles inverses se forment après les plis à la base des anticlinaux. Le plissement est localisé en avant du décrochement principal, au-dessus de failles inactives enfouies affectant le substratum du bassin de l'Oriente. Le bassin de l'Oriente est un modèle naturel exceptionnel pour l'étude de déformations transpressives actives le long d'un décrochement actif majeur

A Natural Model of Active Transpressional Tectonics the en Échelon Structures of the Oriente Deep, Along the Northern Caribbean Transcurrent Plate Boundary (Southern Cuban Margin)

A seabearn and seismic reflection structural study of the Oriente Deep, located along the northern Caribbean transcurrent plate boundary, allows us to image in three dimensions active transpressional structures (cruise SEA-CARIB II, R/V Jean Charcot). These structures are folds and reverse faults. The folds display an en échelon arrangement and are set within three E-W trending alignments. The folds appear with an axis trending 30° to 40° to the shear direction. Their axes have undergone a rotation which gives them in plan a sigmoidal Zshape. The reverse faults formed after the folds and are located at the bases of the anticlines. The folding occurs outside the main strike-slip fault, above inactive burried faults affecting the basement of the Oriente Deep. The Oriente Deep is a exceptional natural model for the study of active transpressional deformation along a major strike-slip fault

Campagne Seamat: Etude de la collision de la ride Est-Pacifique avec le continent Nord-Americain

The data of the Seamat Cruise indicate that: a) the junction between the East Pacific Rise and the Rivera Fracture Zone is located 165 km seaward the Acapulco Trench axis at 18 degree 30'N latitude and 106 degree 15'W longitude; and b) the East Pacific Rise axial ridge connects the Rivera Transverse Ridge trough an overshot ridge. This situation makes the Rivera Fracture Zone located eastward of the junction progressively inactive and documents a westward jump of the junction

Plate boundary segmentation in the northeastern Caribbean from geodetic measurements and Neogene geological observations,

International audienceThe Caribbean–North America plate boundary in the northeastern Caribbean shows a remarkable example of along-strike transition from plate boundary–normal subduction in the Lesser Antilles, oblique subduction with no strain partitioning in Puerto Rico, and oblique subduction/collision with strain partitioning further west in Hispaniola. We show that this segmentation is well marked in the interseismic strain, as measured using space geodetic data, and in the Neogene deformation regime, as derived from geological observations. Hence, interseismic segmentation, which reproduces the geological segmentation persistent over a long time interval, is inherited from the geological history and long-term properties of the plate boundary. This result is relevant to the assessment of seismic hazard at convergent plate boundaries, where geodetic measurements often show interseismic segmentation between fully–and partially–coupled plate interface regions

Imbricated scars on the Ligurian continental slope: evidence for multiple failure events in the 1887 earthquake epicentral area

International audienc