Architecture and processes in modern and ancient deep-marine channel complexes.

Quantitative analysis of modern submarine channels has permitted a more rigorous classification than has hitherto existed. Channel sinuosity varies with slope gradient, reaching a maximum sinuosity at an optimum gradient. Modern submarine channels may be classified by maximum sinuosity and slope gradient giving high-sinuosity, low-gradient, to low-sinuosity, high-gradient channels. This study highlights similarities between the geometry of submarine meanders and those of large terrestrial rivers. An architectural element analysis scheme is presented in this thesis to enable qualitative comparisons between modern and ancient channels. For submarine channels, using this architectural element scheme, two end-member models are proposed for modern and ancient systems. This thesis examines the classic channel-complex deposits of the Eocene Hecho Group, south-central Pyrenees, Spain, to emphasise the range of channel architectural styles found in a foreland basin. Seven distinct channel types are recognised in this basin, generally representing different levels of erosional and depositional architecture and facies. A variety of modern and ancient submarine channel elements have been studied to show that channel architecture is strongly controlled by the type of channelised flow process. Synthesising data from modern and ancient channels provides some predictions about preferential sites of sand accumulation within channel-levee complexes, e.g., at channel bends associated with flow stripping; channel confluences; point bar deposits; channel benches and terraces; channel thalwegs; and other hitrachannel hydraulic jump sites, such as cross channel growth faults.