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William D. McCaffrey1, Sanjeev Gupta2
(1) Leeds University, Leeds, United Kingdom
(2) Imperial College, London, United Kingdom

Abstract: Controls on the incision, filling and abandonment of coarse-grained turbidite channels, Grés du Champsaur, Alpine foreland basin, south-eastern France

Submarine channels may exhibit a range of styles from purely aggradational (levee-confined) through mixed incisional-aggradational to purely incisional (confined by erosional topography). We present a process-oriented study of the architecture of an exceptionally well-exposed 2-km-wide turbidite channel complex that comprises both incisional and depositional elements. The paleomorphology of the channel complex can be reconstructed on a scale of several kilometers, allowing the sedimentary architecture (including 3D connectedness) to be defined, and allowing a process-based interpretation of facies development to be made. In contrast to sinuous aggradational systems, this system evolved two (and possibly more) separate, relatively straight channels. These appear to enjoy a high degree of connectedness, due to the development of extensive tabular sands connected to the uppermost levels of the channel fill, and the deeply incisional nature of the channel axes. In common with many other systems, this system appears to evolve from a channelised to non-channelised form and vice versa. "Fill and spill"- type models cannot be applied straightforwardly to account for the development of this channel system. Instead it seems more likely that spatially-variable degrees of lateral confinement in conjunction with tectonically-driven gradient changes may have played a significant role in channel initiation. Our study has important implications for the identification and characterisation of the geometry of incisional turbidite channel complex deposits in the subsurface.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana