Interactions between active faulting, volcanism, and sedimentary processes at an island arc: Insights from Les Saintes channel, Lesser Antilles arc

Abstract

International audienceNew high-resolution marine geophysical data allow to characterize a large normal fault system in the Lesser Antilles arc, and to investigate the interactions between active faulting, volcanism, sedimenta-ry, and mass-wasting processes. Les Saintes fault system is composed of several normal faults that form a 30 km wide half-graben accommodating NE-SW extension. It is bounded by the Roseau fault, responsible for the destructive Mw 6.3 21 November 2004 earthquake. The Roseau fault has been identified from the island of Basse-Terre to Dominica. It is thus 40 km long, and it could generate Mw 7 earthquakes in the future. Several submarine volcanoes are also recognized. We show that the fault system initiated after the main volcanic construction and subsequently controls the emission of volcanic products. The system propagates southward through damage zones. At the tip of the damage zones, several volcanic cones were recently emplaced probably due to fissures opening in an area of stress increase. A two-way interaction is observed between active faulting and sedimentary processes. The faults control the development of the main turbiditic system made of kilometer-wide canyons, as well as the location of sediment ponding. In turn, erosion and sedimentation prevent scarp growth at the seafloor. Faulting also enhances mass-wasting processes. Since its initiation, the fault system has consequently modified the morphologic evolution of the arc through perturbation of the sedimentary processes and localization of the more recent volcanic activity

Quaternary coral reef complexes as powerful markers of long-term subsidence related to deep processes at subduction zones: Insights from Les Saintes (Guadeloupe, French West Indies)

“…The islands in the Saintes archipelago are the remnants of ancient volcanoes. We consequently hypothesized the shape of the volcanic construction prior to platform growth to be conical (or linear along a transect) like modern subaerial or submarine active volcanoes (see for example the nearby submarine Colibri volcano, in the Les Saintes channel in Leclerc et al (2016)). A batch of models was run with this linear slope, for two initial slope values, 0.075 m/m and 0.02 m/m, which would correspond, respectively, to the western and eastern slope of the islands, calculated between the coast and the slope break at ~250 mbsl.…”

“…We also ran models that take into account the fact that the modern Les Saintes plateau is offset by small normal faults. These faults have 5-8-m-high scarps on the plateau, whereas they can have scarps up to 50 m high southward, in the Saintes Trough (Leclerc et al, 2016, see Marigot and Pompierre faults). This system initiated after the main volcanic construction in the area, and faulting has certainly offset the volcanic slopes of the Les Saintes volcanic edifice prior to reef settlement.…”

“…2). Small NW-SE-striking normal faults crosscut and offset its surface by up to 8 m. They belong to the regional fault system that crosscuts Les Saintes area (Feuillet et al, 2011b;Leclerc et al, 2016).…”

Petrophysical properties of volcanic rocks and impacts of hydrothermal alteration in the Guadeloupe Archipelago (West Indies)

“…Coutant et al, 2012;Gaudin et al, 2016Gaudin et al, , 2015Gaudin et al, , 2013Lesparre et al, 2016;Pozzi et al, 1979;Rosas-Carbajal et al, 2016;Samper et al, 2009). Moreover, the recent offshore seismic activity between Les Saintes and Dominica relaunched studies on the structural framework of the archipelago (Bazin et al, 2010;Escartín et al, 2016;Feuillet et al, 2011;Leclerc et al, 2016Leclerc et al, , 2014. 7 Bouysse and Westercamp, 1990;Feuillet et al, 2002;Symithe et al, 2015).…”

“…Groundmass K/Ar ages from Blanc, 1983;Carlut et al, 2000;Ricci et al, 2015bRicci et al, , 2015aRicci et al, , 2017Samper et al, 2007Samper et al, , 2009. Major faults from Calcagno et al, 2012;Feuillet et al, 2002;Leclerc et al, 2016. d and e) Location map of studied samples with the different rock types and their degree of alteration: d) Basal Complex in the northern part of Basse-Terre Island; e) Vieux-Habitants-Bouillante area. f) Location of studied samples and simplified geological map of Terre-de-Haut with the dominant lithotypes in each area.…”