LALLEMAND , Serge

Absolute earthquake hypocenter locations have been determined in the area offshore eastern Taiwan, at the Southernmost Ryukyu subduction zone. Location process is run within a 3D velocity model by combining the Taiwanese and neighboring Japanese networks and using the 3D MAXI technique. The study focuses on the most active seismic cluster in...

Physical modeling of oblique subduction is performed to study the mechanism of strain partitioning. The model is two-layer and includes the elasto-plastic lithosphere (the overriding and subducting plates) and the low-viscosity liquid asthenosphere. The subduction is driven by a push force from a piston and a pull force when the density...

The North Andean convergent margin is a region of intense crustal deformation, with six great subduction earthquakesMw ½ 7:8 this century. The regional pattern of seismicity and volcanism shows a high degree of segmentation along strikeof the Andes. Segments of steep slab subduction alternate with aseismic regions and segments of flat slab...

The initial sediment lithification reactions start with complex interactions involving all components of the sedimentary material (minerals, surface water, decomposing organic matter and living organisms). This is the eogenesis domain (0 to 2000 m below seafloor), covering a burial interval ranging from the interface with the biosphere down to...

Rédigé par l'équipe de recherche du navire L'Atalante de l'Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)

We analyze in this study a new set of marine data including 3D local tomography, 1992-2008 relocated earthquakes and two recent multichannel seismic lines to characterize the deformation style in the collision area offshore east Taiwan. We have mapped in detail the Mohos of the converging plates as well as the subduction interface with a...

The influence of the highly oblique plate convergence at the northern Lesser Antilles onto the margin strain partitioning and deformation pattern, although frequently invoked, has never been clearly imaged. The Anegada Passage is a set of basins and deep valleys, regularly related to the southern boundary of the Puerto Rico-Virgin Islands...

The Taiwan area, where the Philippine Sea Plate collides with Eurasia, is one of the most seismically active areas in the world and has been consequently struck repeatedly by destructive earthquakes. To better constrain the occurrence of large earthquakes, we have conducted two cruises in 2012 and 2013 from which five piston, gravity and...

Recent sedimentary facies and processes along the offshore slope of east Taiwan are investigated using a large set of geophysical and sedimentological data. The Taiwan orogen is often considered as one of the most tectonically active regions in the world and also suffers important climatic activity with an average of four typhoons per year. We...

Taiwan is a young and seismically active mountain belt, where a series of strong earthquakes (M>7) have occurred over the past hundred years. Identifying historical earthquakes around Taiwan is a key to better constrain the geodynamic of this active region. Sedimentological and geochemical analyses of surface sediments from one station offshore...

The southernmost part of the Ryukyu subduction, where the Philippine Sea Plate is subducting under the Eurasian Plate, is known to be a very seismically active region of transition from a north-dipping subduction along the Ryukyu subduction to an ~ SE-NW collision along the Taiwanese orogenic wedge. In this paper, we will focus on the Ryukyu...

Along the convex Northern Lesser Antilles margin, plate convergence obliquity increases northward resulting in subduction normal to the trench to the west of Guadeloupe and highly oblique (>75°) to the North of Virgin Island. In this context, tectonic structures related to strain partitioning has long been debated, but are still poorly imaged....

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We have discovered in a marine core, located 20 km east of the Coastal Range of Taiwan at the top of a 1200 m deep submarine high, sheltered from rivers discharges and gravitational flows, a 23 cm-thick anomalous sequence topped with broken bivalves and wood fragments. Based on radiocarbon dating, we distinguish five sub-events within ∼ 100...

Oceanic crust formed at slow-spreading ridges is currently subducted in only a few places on Earth and the tectonic and seismogenic imprint of the slow-spreading process is poorly understood. Here we present seismic and bathymetric data from the Northeastern Lesser Antilles Subduction Zone where thick sediments enable seismic imaging to greater...

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The Eocene tectonic evolution of the easternmost Caribbean Plate (CP) boundary, i.e. the Lesser Antilles subduction zone (LASZ), is debated. Recents works shed light on a peculiar period of tectonic duality in the arc/back-arc regions. A compressional-to-transpressional regime occurred in the north, while rifting and seafloor spreading occurred...

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In the frame of the ANR program GAARanti, aiming to track regional emersion surfaces and potential timing of land emersion or drowning, we conducted new field studies in islands belonging to the Anguilla Bank (Saint Barthélémy, Saint Martin, Tintamarre and Anguilla), the northernmost bank located in the forearc of the Lesser Antilles subduction...

The Grenada back‐arc basin is located between the Aves Ridge, which hosted the remnant Early Paleogene "Great Caribbean Arc", and the Eocene to Present Lesser Antilles Arc. Several earlier studies have proposed different modes of back‐arc opening for this basin, including N‐S and E‐W directions. The main aim of this study is to constrain the...

Studying back-arc basins, where sedimentation is less deformed than in the forearc, provides complementary information about formation and tectonic evolution of subduction zones. At the Lesser Antilles subduction zone, the North and South American plates are subducting underneath the Caribbean plate at a velocity of 2 cm per year. The...