Part of abstract of ref. 2032:
The structurally low Yauco basin began to receive volcanic rocks, clastic rocks, olistostromes, and olistoliths in Maastrichtian time. Campanian reefs which had grown on the uplifted Jurassic crust slid northward into the basin. Emplacement of reefal debris and olistoliths was synchronous with volcanism and uplift. These processes suggest proximity to submarine volcanoes, possibly in a deforming forearc basin. Surficial exposures of mantle rocks are probably the result of structural inversion of the basin in response to contraction in the currently active east-trending left-lateral fault system. 