Physiography and recent sediment distribution of the Celtic Deep-Sea Fan, Bay of Biscay

摘要: The Celtic Deep-Sea Fan located in the northwestern part of Bay Biscay is a middle sized fan with surface area more than 30,000 km 2 . whole system mature mud/sand-rich submarine on passive margin. Multi-beam echo sounder data, 3.5 kHz seismic and 12 Kullenberg cores were examined to define morphology, lithological characteristics, sedimentary processes relationship between evolution deposits environmental conditions continental shelf. upper characterised by presence two distinct tributary systems: (1) Whittard large, persistent, slightly sinuous channel, which linked southern end Irish Sea River system; (2) Shamrock system, moderate western English Channel system. lower corresponds divergent braided secondary channels associate lobes. Successive lobe elements, without impor- tant relief, generated during periodic avulsions channels. lithological, palaeontological, geochemical analyses show sedimentation since last glaciation. During lowstand rise sea-level frequent low-density turbidity currents predominant deposited sediments throughout They initiated at front deltaic environment outer-shelf. high conditions, occasional high-density and/or non-cohesive debris flows occur responsible for sand deposition middle-lower fan. are derived from reworked sands due high- energy outer Thus Fan, variations hydrodynamic Shelf seem be primary control facies shift growth. q 2000 Elsevier Science B.V. All rights reserved.