--> Abstract: New Insight into Sediment Deposition from Turbidity Currents and ‘Linked’ Debris Flows; #90063 (2007)

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New Insight into Sediment Deposition from Turbidity Currents and ‘Linked’ Debris Flows

 

Talling, Peter J.1, Russell B. Wynn2, Lawrence Amy3 (1) University of Bristol, Bristol, United Kingdom (2) National Oceanography Centre, Southampton, Southampton, United Kingdom (3) Heriot-Watt University, Edinbugh, United Kingdom

 

Deposits of individual submarine flows have been correlated over an area of 120 x 30 km in the Miocene Marnoso Arenacea Formation of the Italian Apennines. Bed correlations between 109 sections allow the lateral evolution of sediment density flows to be analysed in detail. This unique field data is compared to ongoing experimental and numerical modelling. Previous models fail to reproduce the observed deposit shape; suggesting a need to iterate basic models of deposition from such flows.

 

Individual beds contain clean turbidite sandstone, mud-rich ‘linked debrite' sandstone, clean ‘linked debrite' sandstone and turbidite mudstone. We present results of settling experiments in static tubes and an annular flume that show how deposit textures can be related to parent sediment concentration, mud content and flow deceleration rate.

 

Most large-volume beds contain an internal erosion surface underlain by inversely-graded sandstone, recording waxing and waning flow. These beds contain 0.7-7 km3 of sediment within the outcrop area, and their total volume may have been significantly greater. Such large volumes suggest flows were triggered by slope failure. This bed architecture suggests that slope failure can generate a waxing and waning turbidity current.

 

Amy, L.A. and Talling, P.J., 2006, Anatomy of turbidites and linked debrites based on long distance (120 x 30 km) bed correlation, Marnoso Arenacea Formation, Northern Apennines, Italy. Sedimentology, 53, 161-212.

Amy, L., Talling, P.J., Edmonds, V.O., Sumner, E.J., and Leseuer, A. (2006) An experimental investigation of sand-mud suspension settling behaviour: implications for bimodal mud contents of submarine flow deposits. Sedimentology, in press.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California