Deep-water turbidite systems: A review of their elements, sedimentary processes and depositional models. Their characteristics on the iberian margins

Abstract

Turbidite systems or submarine fans are considered the most important clastic accumulations in the deep sea and represent the sediment-transfer system between the hinterland source area and the deep-sea depositional sink. Their deposits contain information about global factors and local factors. Different scales and varying observational methods have contributed to the lack of a unifying terminology. In order to solve this problem several authors have proposed an “elemental approach”. The main architectural elements defining a turbidite system are: large-scale erosive features (mass-movements and canyons), channels and channel-fill deposits, overbank deposits and lobes. The sediment making up these elements is principally from gravity flow deposits, the most widely recognised being the turbidite, and other submarine mass movements. The genesis and character of these elements, as well as the overall geometry of the systems, indicate they are formed by a complex interaction between global and local factors. Various turbidite-system classifications are found in the literature, the most widely-used being based on grain size and feeder systems. Besides the scientific importance of turbiditic systems, they are predominantly studied because of the economic interest in them, as turbidite sandstones constitute important gas and oil reservoirs. Turbidite systems shape the seafloor of the Iberian continental margins and contribute in a large part to their outbuilding and basin infilling. They are hugely variable in size, location within the physiographic domains, style and overall geometry of the architectural elements, as well as sediment composition. The most studied Iberian turbidite fans are in the Mediterranean Sea whereas those of the Atlantic Ocean remain poorly known.