Role of Storms and Prevailing Energy in Defining Sediment Body Geometry, Composition, and Texture from Caicos Platform

Harold R. Wanless
Geological Sciences, University of Miami, Coral Gables, FL

Pleistocene and Holocene carbonate sediment bodies on Caicos Platform are created by a combination of major storm events and prevailing energy conditions. Major long-period oceanic swell events together with hurricane surges have built pronounced coastal beach ridges on exposed north-facing margins and create elongate reef-rubble lobes within back-reef lagoons. Major hurricane surges have defined the location and geometry of Holocene platform-interior sand shoals, an elongate leeward-margin shallow subtidal sand shoal, fanning longitudinal sand ridges extending in from leeward margins, and coarse skeletal gravels layers in and towards the base of the platform-interior grainstone sequence. Hurricane events of all scales also have built extensive south-facing peritidal flats and defined the depositional texture and fabric of accumulating Callianassa bioturbated platform-interior grainstones and packstones.

Within the framework of pre-existing and storm-generated topography/bathymetry, prevailing brisk easterly Trade Winds and prevailing oceanic swells provide agitation for growth and expansion of ooid grainstone shoals and beach strand plains on the platform interior and margins respectively. Prevailing conditions also define the distribution and productivity of coral, seagrass and other benthic communities.

Although tidal currents provide important water renewal and create local sediment bodies, it is hurricanes, large oceanic swell events and prevailing wind-wave and swell conditions that have defined sediment body forms, features, and textural components of Caicos Platform. Twenty to forty winter cold fronts pass through Caicos each year followed by brisk northerly winds. Their primary contribution is to leave the south flanks of islands leeward so that peritidal flats are not eroded.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas