Pol Guennoc

... Jean-Noël Proust 1 , Mathieu Renault 1 , Pol Guennoc 2 and Isabelle Thinon 2 ... Massif armoricain (source IGN, pas à 50 m). La zone côtière hachurée montre la localisation des reliefs faillés et sub-mergés du Massif armoricain (le « Précontinent Breton ») incisé par ...

ABSTRACT The Messinian Salinity Crisis is a huge outstanding succession of events that has deeply modified the Mediterranean area within a short time span at the geological scale. The seismic atlas of the Messinian markers in the Mediterranean and Black seas is a collective work summarizing, in one publication with a common format, the most relevant seismic features related to this exceptionnal event. Seismic information has been collected over many years from the offshore domain. Throughout 13 study areas, the seismic facies, geometry and extent of the Messinian markers (surfaces and depositional units) are described. The absolute time succession of the Messinian events, or the processes responsible for their occurrence in space and time are not discussed. The objectives of this atlas are: (1) to image the Messinian seismic markers from the main margins and basins; (2) to propose a new global and consistent terminology for these markers in the entire offshore Mediterranean area and (3) to make this information accessible to the non-geophysicist community. Interpreted seismic data were carefully selected according to their quality, position and significance in order to reach these objectives, and are presented here. Raw and interpreted seismic profiles are available on CD-Rom. The atlas costs 20 euros and can be ordered online here: http://ccgm.org/en/home/148-seismic-atlas-of-the-messinian-salinity-crisis-markers-2853630978.html or http://www.geosoc.fr/publication/memoires/memoires-nouvelle-serie.html

Marie-Galante basin in the Lesser Antilles fore arc has experienced high amplitude (up to several thousand meters) vertical movements in response to both local tectonic in the fore-arc (trench perpendicular extensional tectonic) and geodynamical events at the plate interface, such as, long term interplate coupling changes, or ridges subduction or alternating period of under-platting/basal erosion... During the KaShallow cruises, we

In order to understand the structural context of the Bouillante geothermal field, ADEME and BRGM has carried out offshore studies on the western shelf of Basse-Terre Island. Detailed analysis of high-resolution seismic, bathymetric and magnetic data allowed determination of the origin of the submarine topography, distribution of the sedimentary units, morphology of the basement and offshore continuation of the tectonic structures identified onshore. The present-day morphological features of the shelf are mainly related to the latest post-glacial deposits. Off the Bouillante bay, a thick sedimentary deposition has induced an important widening of the shelf, thus hiding the real morphology of the basement. The sedimentary cover has recorded two major erosions - low sea-level phases, the last one being correlated with the last 20 ky glacial maximum. The main faults, offshore the geothermal field anomaly, have been mapped. The N160°W escarpment, which bounds the shelf, may be a major si...

La campagne océanographie BATHYMAY, effectuée en janvier 2004 à bord du navire océanographique Marion-Dufresne 2, a permis de reconnaître pour la première fois la totalité des fonds marins de Mayotte, à l’extérieur du lagon. L’analyse de l’imagerie révèle que Mayotte est un massif volcanique de plus de 4400 m de hauteur, avec de larges canyons qui incisent toute la pente insulaire, de nombreux édifices volcaniques sous-marins et des glissements de grande ampleur dans le Nord-est et le Sud-Ouest. Des falaises abruptes limitent de vastes plateaux sous-marins dans l’Ouest de Mayotte.

... Jean-Noël Proust 1 , Mathieu Renault 1 , Pol Guennoc 2 and Isabelle Thinon 2 ... Massif armoricain (source IGN, pas à 50 m). La zone côtière hachurée montre la localisation des reliefs faillés et sub-mergés du Massif armoricain (le « Précontinent Breton ») incisé par ...

The Lesser Antilles are located on the Eastern border of the Caribbean plate, a region of intense tectonic activity, as evidenced by the important historical and instrumental seismicity. Although most of the deformation is located along the subduction zone, several faults cutting the arc could be active structures. In the Guadeloupe archipelago (French Caribbean), possible active faults have been proposed either onshore and offshore. The FAGUAD and AGUADOMAR cruises yielded crucial observations on tectonic structures such as the Marie-Galante Graben. Unfortunately the resolution of geophysical data was not sufficient to clearly identify traces of recent to active tectonic deformations. Moreover, the strong erosion shaping these tropical islands limit exhaustive observations of onshore tectonic activity. To evaluate the possibility of active faulting near the Guadeloupe-Marie Galante Islands, the BRGM (French Geological Survey) carried out, in December 2003, the GEOBERYX campaign. Th...

... Isabelle Thinon 1 , Pol Guennoc 1 , Adnand Bitri 1 and Catherine Truffert 1 ... The Lesser Antilles arc (fig. 1 Go ) is an 850 km long archipelago between the Caribbean Sea and the Atlantic Ocean that comprises twenty islands, including the French Lesser Antilles. ...

ABSTRACT The Messinian Salinity Crisis is a huge outstanding succession of events that has deeply modified the Mediterranean area within a short time span at the geological scale. The seismic atlas of the Messinian markers in the Mediterranean and Black seas is a collective work summarizing, in one publication with a common format, the most relevant seismic features related to this exceptionnal event. Seismic information has been collected over many years from the offshore domain. Throughout 13 study areas, the seismic facies, geometry and extent of the Messinian markers (surfaces and depositional units) are described. The absolute time succession of the Messinian events, or the processes responsible for their occurrence in space and time are not discussed. The objectives of this atlas are: (1) to image the Messinian seismic markers from the main margins and basins; (2) to propose a new global and consistent terminology for these markers in the entire offshore Mediterranean area and (3) to make this information accessible to the non-geophysicist community. Interpreted seismic data were carefully selected according to their quality, position and significance in order to reach these objectives, and are presented here. Raw and interpreted seismic profiles are available on CD-Rom. The atlas costs 20 euros and can be ordered online here: http://ccgm.org/en/home/148-seismic-atlas-of-the-messinian-salinity-crisis-markers-2853630978.html or http://www.geosoc.fr/publication/memoires/memoires-nouvelle-serie.html

Recent seismic profiles have revealed that in the Gulf of Lions, the Late Miocene platform is offset by a number of normal structures associated with extension dating from the latest Miocene - earliest Pliocene. The cause of this extension has yet to be clearly identified, but it is thought to be associated with uplift in the east of the Pyrenees

Marie-Galante basin in the Lesser Antilles fore arc has experienced high amplitude (up to several thousand meters) vertical movements in response to both local tectonic in the fore-arc (trench perpendicular extensional tectonic) and geodynamical events at the plate interface, such as, long term interplate coupling changes, or ridges subduction or alternating period of under-platting/basal erosion... During the KaShallow cruises, we

ABSTRACT New high-resolution seismic data complemented with bedrock samples allowed us to propose a revised geological map of the Bay of Seine and to better define the control by the geological substrate on the morphogenesis and evolution of the Seine River during Pleistocene times. The new data confirm previous works. The Bay of Seine can be divided into two geological parts: a Mesozoic monocline domain occupying most of the bay and a syncline domain, mostly Tertiary, in the north, at the transition with the Central English Channel area. The highlighting of Eocene synsedimentary deformations, marked by sliding blocks in the syncline domain, is one of the most original inputs of this new study in the Bay of Seine that underlines the significant role of the substrate on the formation of the Seine paleo-valley. In the monocline domain, three terraces, pre-Saalian, Saalian and Weischelian in age respectively, constitute the infill of the paleovalley, preferentially incised into the middle to upper Jurassic marl-dominated formations, and bounded to the north by the seaward extension of the Oxfordian cuesta. The three terraces are preserved only along the northern bank of the paleovalley, evidencing a NE-to-SW migration of the successive valleys during the Pleistocene. We assume this displacement results from the tectonic tilt of the Paris Basin western margin. In the North, the paleo-Seine is incised into the axis of the tertiary syncline, and comprises three fill terraces that are assumed to have similar ages than those of the terraces. The fill terrace pattern is associated to the subsiding character of this northern domain of the Bay of Seine.

... (14/04/2006). 1 : Institut de Géoarchitecture. Université de Bretagne Occidentale - Brest : EA2219 – Institut Supérieur des Sciences et Technologies de Brest (ISSTB) – Université de BretagneSud : EA2219 – Maison des Sciences de l'Homme de Bretagne. ...

A high-quality aeromagnetic survey of northern Brittany (line spacing 250 m flight elevation 150 m) has been used to delineate the Lower Carboniferous St Malo dyke swarm in detail. The dyke swarm fans at its northern and southern ends, and is affected by N60 deg sinistral transcurrent faults. After restoration of these offsets, the full structure trends in a N-S