Magnetic and physical properties of sediment cores collected along the Lesser Antilles accretionary wedge : natural hazards and influence of lithological changes on the paleomagnetic signal

• Main Author: Bieber, Arthur
• Other Authors: Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Paris Cité, Université du Québec à Rimouski, Nathalie Feuillet, Guillaume St-Onge
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2022
• Subjects: Quaternary; Lesser Antilles; Paleoseismology; Paleomagnetism; Turbidites; Homogenites-Turbidites complexes; Quaternaire; Petites Antilles; Paléosismologie; Paléomagnétisme; Complexes homogénites-Turbidites; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; North Atlantic
• Online Access: https://theses.hal.science/tel-04210775; https://theses.hal.science/tel-04210775/document; https://theses.hal.science/tel-04210775/file/va_Bieber_Arthur.pdf

The Lesser Antilles volcanic arc result from the Atlantic plates subducting beneath the Caribbean plate. En echelon fault system accommodates oblique convergence component that generate several earthquakes such as offshore Martinique (M=7.4) in 2007. Subduction interface megathrusts can be devastating, as reported in 1839 and 1843 offshore Martinique and Guadeloupe islands. It is essential therefore to better understand how this subduction zone and its seismic cycles work. In this context, the CASEIS expedition took place during the summer 2016. Several sediment piston-cores and a number of seismic profiles were collected to better constrain the seismic hazard over the recent Quaternary. Several studies reveal rapidly deposited layers (RDL) especially turibidite as good stratigraphic marker for seismic event. If such deposits are found simultaneously in several basins of the Lesser Antilles, then these deposits were most probably triggered by seismic events. In addition, homogenite-turbidite complexes were already identified in this region and are probably the fingerprint of megathrusts or associated tsunamis. Using physical, magnetic, and lithologic parameters of five sediment cores, this thesis shows how paleomagnetism can be useful for marine paleoseismologic studies. In the first chapter, a regional magnetostratigraphy is established using relative paleointensity variations (RPI), oxygen isotopes and geomagnetic reversals. Core CAS16-24PC, which was collected on a topographic high of the accretionary wedge, is dated at over 1.15 Ma. By comparing paleomagnetic and isotopic data to well dated stacks, many tie-points allowed to better constrain the chronostratigraphy of the entire core.The second chapter uses previously published radiometric dating (carbon 14), the regional magnetostratigraphy, and the North Atlantic paleointensity stack to date four cores and to estimate RDL ages for three of these cores. These cores were retrieved in disconnected fore-arc and accretionary prism basins. These basins are also ...