Morne Patates volcano, southern Dominica, Lesser Antilles

Abstract

AbstractMornes Patates is the youngest volcano in Dominica occupying a depression on the southwestern flank of a larger stratovolcano, Morne Plat Pays. Within the depression an arcuate ridge, apparently of acid andesite lavas, has been cored and largely buried by the explosive emplacement of two acid andesite domes and their associated pyroclastic deposits, mainly block-and-ash flow deposits. A basaltic scoria horizon, exposed on the northern side of the depression, has a14C age of 28450 ± 1500 years B.P. and is not seen on the volcano itself, which suggests that the domes and pyroclastic rocks are younger than this. A14C age of 450 ± 90 years B.P. from a block-and-ash flow deposit from the Morne Patates dome apparently confirms this and the youthful morphology also suggests a young age. The angular shape of the depression and the steep submarine slopes are consistent with an origin as a lateral gravity slide rather than a caldera collapse. Vigorous fumarolic activity and swarms of local earthquakes suggest that magma exists at depth (several kilometres) beneath the Morne Patates–Morne Plat Pays area.