Discovery of Lower Cretaceous synmetamorphic thrust tectonics in French Lesser Antilles (La Désirade Island, Guadeloupe): Implications for Caribbean geodynamics

Abstract

[1] Located east of Guadeloupe, the island of La Désirade exhibits the oldest rocks of the Lesser Antilles arc and the eastern Caribbean plate. An old magmatic basement is composed of (1) late Jurassic ophiolitic complex with meta-basaltic pillow lavas and interbedded radiolarites, (2) acid igneous complex comprising meta-quartz-diorite and meta-rhyolitic lavas flows, and (3) meta-diabasic/microdioritic dyke swarm complex. We present and discuss the discovery of synmetamorphic thrust tectonics in this island. Based on detailed structural analysis we evidenced two main compressive events. The first event (D1) is characterized by pervasive folding associated with thrust development. In the northeastern part of the island, a major thrust fault, the Grand Abaque Thrust, has been discovered which displaces for several kilometers the acid igneous complex onto the ophiolitic unit. The second deformation event (D2) is featured by a main pervasive cleavage S2 observed at the regional scale associated with upright folding (F2) and by the development of two sets of conjugated steeply dipping strike-slip shear zones, dextral 130°N and sinistral 20°N striking, respectively. Microstructural observations indicate that Greenschist facies metamorphism is clearly contemporaneous with the development of D1 and D2 superimposed tectonic structures. Ar/Ar geochronology was performed on two bulk of adularia minerals sampled in the northeast volcanic complex within a deformed zone related to a D2 event. These analyses yield well-defined and concordant plateau ages at 106.2 ± 1.7 Ma and 107.2 ± 1.8 Ma. Thus, shortening and thickening tectonics occurred during Lower Cretaceous (Albian). In the available framework of Caribbean geodynamics, the synmetamorphic thrust tectonics we discovered in the French Lesser Antilles is related to the collision between an Aptian-Albian oceanic plateau and the Andean-Cordilleran east-dipping subduction zone. Our results support subduction polarity reversal during Lower Cretaceous.

Tectonic and sedimentary architecture of the Karukéra spur: A record of the Lesser Antilles fore-arc deformations since the Neogene

“…7). Following this interpretation, the Karukéra basement is considered similar to the La Désirade one which is composed of Jurassic-lower Cretaceous Arc/ Back-arc metavolcanics (Cordey and Cornée, 2009;Corsini et al, 2011;Lardeaux et al, 2013;Neill et al, 2010). Tomographic data from wide angle seismic experiments over the spur and La Désirade did not reveal any crustal discontinuity or strong velocity gradient in the horizontal dimension Roux, 2007).…”

“…The faults dip either northward or southward. Corsini et al (2011) and Lardeaux et al (2013) revealed ante-cretaceous inherited N40°± 10 shear zones in La Désirade island basement, too. We conclude that these basement structures were also reactivated as normal faults during the Cainozoic history of the forearc.…”

“…When observed perpendicular to these faults trend, the spur appears as a wide east-northeastward tilted bloc culminating along the Western Flank and broken into several smaller size, east-northeastward tilted compartments. Corsini et al (2011) and Lardeaux et al (2013) revealed ante-Cretaceous, inherited N130°± 10 shear zones in La Désirade island basement. We conclude that this first fault set corresponds to structures reactivated as normal faults during the Cainozoic history of the fore-arc.…”

La Désirade island (Guadeloupe, French West Indies): a key target for deciphering the role of reactivated tectonic structures in Lesser Antilles arc building

“…In the light of recent and detailed paleontological, geochemical and geochronological investigations [Gauchat, 2004;Mattinson et al, 2008;Cordey and Cornée, 2009;Neill et al, 2010;Corsini et al, 2011] it is now widely accepted that the magmatic basement of La Désirade island was generated during Late Jurassic. In the framework of Guadeloupe archipelago [modified after Feuillet et al, 2002 andThinon et al, 2010].…”

“…1), the island of La Désirade exhibits the oldest rocks of the Lesser Antilles arc and the eastern Caribbean plate and represents the exhumed base of the active Lesser Antilles volcanic arc on which only indirect information is available. Moreover, recent investigations have clearly shown the importance of lower Cretaceous thrust tectonics as well as Pliocene extensional tectonics in the structural evolution of this island [Léticée, 2008;Cordey and Cornée, 2009;Corsini et al, 2011;Münch et al, 2013]. The latter represents therefore a key target for understanding the role of inherited structures for the development of current tectonic setting of the Lesser Antilles arc.…”