Tectonic evolution of Les Saintes archipelago (Guadeloupe, French West Indies): relation with the Lesser Antilles arc system

Abstract

International audienceIn this paper, we provide the first structural map of Les Saintes archipelago (Guadeloupe, Lesser Antilles). The finite strain pattern displays four families of fault systems characterized by their statistical structural orientations: N000-N020, N050-N070, N090-N110 and N130-N140 trending fault systems. Our onshore results thus underline a fault network much more complex than the one depicted by the previous offshore geophysical investigations around Les Saintes archipelago, which show only N120-N150 trending system. According to the available K-Ar dating of the volcanic rocks and the relative chronology of the faults defined in the field, we determine the deformation history in Les Saintes islands since the last 3 Ma. The four highlighted trending fault systems are already active since the Pliocene and are consistent with the present-day extensional tectonics in the Guadeloupe archipelago compatible with the reactiva-tion of inherited structures at the active arc scale. We interpret the tectonic evolution of Les Saintes islands as the result of interplay between subduction of aseismic ridges (Tiburon and Barracuda ridges) and oblique convergence. Furthermore , we recognized an exhumed geothermal paleo-system in Terre-de-Haut island which is a good analogue of the present-day active Bouillante geothermal system. Its duration is estimated at 400 k.y. during the Pliocene

Tectono-metamorphic evolution of shallow crustal levels within active volcanic arcs. Insights from the exhumed Basal Complex of Basse-Terre (Guadeloupe, French West Indies)

“…To the east, Guadeloupe consists of Grande-Terre, La Désirade, Petite-Terre and Marie-Galante Islands, on which early Pliocene-middle Pleistocene limestones were deposited upon volcanic and/or sedimentary crust (Bouysse and Garrabé, 1984;Andreieff et al, 1987;Bouysse et al, 1993;Cornée et al, 2012;Lardeaux et al, 2013;Münch et al, 2013Münch et al, , 2014. To the west, Guadeloupe is composed of Basse-Terre and Les Saintes Islands, which correspond to the inner active arc (Andreieff et al, 1987;Westercamp, 1988;Carlut et al, 2000;Mathieu et al, 2013;Zami et al, 2014;Verati et al, 2016). Basse-Terre consists of a cluster of volcanic complexes, frequently called "volcanic chains", with from north to south (Samper et al, 2007): the oldest Basal Complex characterized by a 3 to 2 Ma aged volcanism, the Septentrional Chain between 1.8 to 1.1 Ma, the Axial Chain active from 1 to 0.4 Ma, the Grande Découverte -Trois Rivières Complex (0.2 Ma-recent) including the present-day active La Soufrière volcano (Boudon et al, 1987(Boudon et al, , 2008, and the Monts Caraïbes Chain built at around 0.6-0.4 Ma (Blanc, 1983;Ricci et al, 2017).…”

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

“…Tectonic sketch map of the main faults. Modified from Jacques and Maury (1988a) and Verati et al (2016) according to field observations. K-Ar ages (Myr) are from Zami et al, 2014.…”

“…1f). Verati et al (2016) characterized this area as an exhumed geothermal system and described paragenesis associated with hydrothermal alteration. 9…”

“…Hydrothermal alteration in the central part of Terre-de-Haut consists in the development of smectite, kaolinite, veins of quartz, pyrite and gypsum (Jacques and Maury, 1988a). Verati et al (2016) specified the high temperature association. They observed a first high-temperature association composed of chlorite and epidote aggregates developed as pseudomorphs of primary magmatic clinopyroxenes and plagioclases.…”

“…These properties have been measured both on fresh rocks coming from Vieux-Habitants-Bouillante area and older exhumed rocks of the Basal Complex and Terre-de-Haut which could have been buried in the same thermal and pressure conditions as rocks of the currently exploited Bouillante geothermal field. Indeed, the central part of Terre-de-Haut was defined as an exhumed geothermal system by Verati et al (2016). The volcanic activity of the Basal Complex occurred coevally with Terre-de-Haut (Zami et al, 2014).…”