Depositional Dynamics and Sedimentary Bodies in Temperate-Type Carbonate Systems

Lucia Simone and Gabriele Carannante
Napoli University, Napoli, Italy

Based on the study of Meso-Cenozoic limestones and Recent counterparts from the Mediterranean Region, the temperate (foramol) carbonate depositional settings appear to be open systems supporting complex arrangements of winnowed, partially remobilized and/or resedimented lithofacies. The winnowing and remobilization processes act on shelves whose margins may be more or less steep, depending on the depositional, erosive and/or tectonic controls. Related carbonate factories are characterized by a low in situ preservation potential of the produced calcite-dominated bioclastic debris whose early cementation is very rare. Storm-related cohesionless gravity flows may easely transport sediments offshore from marginal areas of the shelf. Major episodes of resedimentation of bioclastic debris are periodic and/or intermittent, related with terminal high stands and/or regressive phases of the sea level. An active presorting of the bioerosion-derived skeletal debris results in early off-shelf swepting and fall-out of the shelf-derived fines, and in off-shelf transport of coarse skeletal debris by means of sand flows. A relatively low aggradation along with a strong tendency to the progradation characterize the temperate open depositional settings with a significant downdeep migration of the main depocenters. In some cases, complex channel networks act as sediment pass-way toward deeper areas. The resulting progradational wedges are made up of uncemented skeletal grainstone sheets and/or elongated channel-related, partially cemented sandy bodies, intercalated with muddy-silty deposits. The resulting sedimentary complex differs from the tropical carbonate systems in terms of nature and mineralogy of the components, sedimentary texture, diagenetic potential, 3D geometries. Knowledge of this model becomes crucial in oil exploration.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005