INFLUENCES OF PALEOTOPOGRAPHY ON FACIES DISTRIBUTION AND MORPHOLOGIES OF MIOCENE CARBONATE PLATFORM DEPOSITS, LA RELLANA PLATFORM, SOUTH EASTERN SPAIN

Recent study of the Rellana platform in the Cabo de Gata region of southeastern Spain represents the initial descriptions of stratigraphy, facies and morphologies of a relatively unstudied field area within a large, well studied region. The platform is characterized by 2.5 kilometers of exposed Miocene to Pliocene carbonate deposits which display preserved paleotopography between Aqua Amarga basin to the North, and the San Pedro area to the South. Platform deposits range from heterozoan carbonate assemblages to photozoan coralgal reef deposits, both displaying evidence for a variety of depositional environments. Study of the platform allows for analysis of platform depositional characteristics as well as provides a link between the platform deposition and equivalent or related deposits in adjacent basins.

Carbonate deposits on the platform are at high elevation (up to 250 meters above sea level) and are influenced by a subtle drainage divide throughout the development of the platform. This exposure allows for comparison of platform deposits on the steeply dipping paleotopography to the south west (~20°) and the more gently dipping paleotopography to the north (~5°). The deposits south of the divide are characterized by steeply dipping heterozoan deposits in the early development of the platform, later reef development over this substrate displays lower rates of backstepping and progradation. North of the drainage, deposition is characterized by thinner heterozoan deposits and a well preserved transition from early aggradational reef development to progradational and downstepping reef development occurring at a higher rate.

Regionally, analysis of the platform area allows for detailed examination of the transition of platform deposits into the neighboring Aqua Amarga basinal deposits to the north. The stratigraphic measurements associated with this project and the previously described deposits allow for direct comparison of platform facies with time equivalent deposition on platform flanks and in the basin. The continuity of these exposures facilitated the correlation of platform and basinal deposits, allowing for the development of a more complete description of the stratigraphic development of the area which was not previously available.