Bathymetry and sediment dispersal dynamics along the Yallahs fan delta front, Jamaica

Abstract

The shallow offshore Yallahs fan delta serves as a model for the interaction of littoral processes and bathymetry and how they influence sedimentation on steep submarine slopes and in deep marine basins in tectonically active areas. Bottom reflection profiles show that the Yallahs delta front is characterized by two bathymetric zones, a narrow island shelf and a steep slope dissected by the heads of at least three submarine canyons. The refraction and diffraction of waves across these canyons and shelf control sediment distribution and the alternation of erosional and depositional beaches. A dominantly westward longshore drift transports coarse-grained sediments until they are trapped in the heads of the submarine canyons or temporarily stored on steep, unstable slopes between the canyons. Mass gravity processes presumably move these sediments downslope where they are deposited as turbidites in the Yallahs Basin and out onto the Colombian Abyssal Plain.