Paleogene carbonate systems of Saint Barthélemy, Lesser Antilles: stratigraphy and general organization

Abstract

Saint Barthelemy is the only island of the northern Lesser Antilles where it is possible to investigate in the detail the chronostratigraphy of the mixed carbonate-volcaniclastic deposits of the Paleogene Caribbean volcanic arc. Based on field mapping and new biostratigraphical and sedimentological data, we study the limestone units interbedded in the Paleogene volcaniclastic deposits. We find that four main carbonate units occur instead of previously believed six ones. Based on the ages given by the foraminifera assemblages, and taking into account the recently published 40Ar/39Ar ages of magmatic rocks, the Lower Limestone unit dates Lutetian, the Intermediate Limestone unit late (?) Bartonian-late Priabonian, the Upper Limestone late Priabonian and the Top Limestone unit early Miocene. The Paleogene carbonate beds were deposited on gently dipping submarine volcaniclastic deposits issued from emergent volcanoes, in muddy, unrimmed inner to mid-ramp setting dominated by bottom communities. A major subaerial unconformity is evidenced during the Oligocene, most probably corresponding to uplift affecting Saint Barthelemy. Our work offers a revised lithostratigraphic succession of Saint Barthelemy as a first key-point for further studies of the Paleogene Caribbean arc deposits which were dismembered following the entrance of the Bahamas Bank in the Lesser Antilles subduction zone.