El arrecife Bía (Mioceno superior de la Cuenca de Fortuna, Murcia). Bioconstrucción de Tarbellastraea Sp. y Porites Sp. compuesta de unidades menores

Abstract

The Cómala reef complex (Upper Miocene , Fortuna Basin, Murcia ) is m ade up of four bioconstructions each separated by sandstone/shale units. One of these bioconstructions, the Bfa reef, has been m apped in detail, allow ing the interpretation of the internal structure, and also the determination of shape and genera distribution of corals. Three rodolith layers mark the boundaries between minor units of a symmetrical mound shape, each one stacking above the former in an aggrading-prograding disposition. The second mound is the best exposed and is taken as a reference for the study of mound structure. It is constituted by corals from the genera Porites and Tarbellastraea whose vertical distribution in the mound nudeous determines a subhorizontal stratification pattern. The coral genera and shape distribution coupled with the stratification pattern suggest that the mound developed as a single reef-mound during stable sea-level conditions