Oligocene to Pliocene paleogeography of the northern Lesser Antilles arc.

Description

In the frame of the GAARAnti ANR-17-CE31-0009 project, we aim at establishing the paleogeography of the arc/forearc areas of the Northern Lesser Antilles over the last 35 Ma to bring constraints for the mammal fauna dispersion paleo-biogeographic models from south America to Greater Antilles. Available paleogeographic maps are ancient (Stephan et al., 1990; Iturralde-Vinent & McPhee, 1999) and contradictive. During that time, the forearc of the Lesser Antilles subduction zone strain pattern accommodated (i) strain partitioning related to subduction obliquity and (ii) progressive trench bending by several episodes of differential vertical and horizontal motions which may have built and/or destroyed continental areas allowing south american terrestrial mammals to reach the Greater Antilles or isolating some south American mammals on newly formed islands. We conducted new studies, onshore on the Anguilla Bank islands and offshore in Kallinago Trough and Wallichi Plateau to reconstruct the evolving paleogeography of this area. We used: 1) new micropaleontological, sedimentological and paleoenvironmental results acquired onshore and from dredged samples during the GARANTI Cruise in may 2017; 2) a database of seismic profiles from various sources: CPEM 1980; ANTITHESIS 2016 and GARANTI 2017 cruises.Onshore, we revised the stratigraphy of the Neogene series. Offshore, we established a seismic stratigraphy and correlated the seismic units and erosional unconformities with the onshore lithostratigraphic successions. We then built paleogeographic maps for different time spans: late Eocene-early Oligocene, late Oligocene-Aquitanian, Burdigalian, early Langhian, mid-late Miocene and Zanclean. During late Eocene-early Oligocene most the area was emergent except in the Kallinago Trough. Significant subsidence periods occurred during Burdigalian and mid-late Miocene and most of the terrestrial areas were drowned. During early Langhian and Zanclean numerous small islands occurred.

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