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William O. Symons, University of Southampton, UK
Esther J. Sumner, University of Southampton, UK
Charles K. Paull, Monterey Bay Aquarium Research Institue, US
Matthieu J.B. Cartigny, National Oceanography Centre, Southampton, UK
Jingping Xu, Ocean University of China, China
Katherine L. Maier, United States Geological Survey, US
Thomas D. Lorenson, United States Geological Survey, US
Peter J. Talling, National Oceanography Centre, Southampton, UK
How accurately can the structure of turbidity currents be reconstructed from their deposits?

Most of our understanding of highly energetic sediment-laden flows (turbidity currents) in the oceans results from analysing the deposits that these flows leave behind in the sedimentary record. It is therefore important to understand how accurately the dynamics of turbidity currents can be reconstructed from their deposits. We used a Remotely Operated Vehicle to collect across canyon transects of push cores in Monterey Canyon, California at the same locations (and others) that the USGS collected flow data in 2002. We find strong correlation between the facies and grain sizes deposited on the canyon walls and measurements of the grain sizes and thickness of flows. Synthesis of deposit data and flow data reveals turbidity currents that experience three phases: 1) flows begin life in the upper canyon as thin, high-energy, high-sediment concentration surges that can transport 1000 kg moorings and deposit chaotic sands and gravels; 2) as flows evolve over both time and space they transform into more dilute sand-rich flows with an expanding head that deposits thin-bedded graded sands and silty mud on the canyon walls; 3) finally the flow expands along its length lofting silty mud that is deposited at high elevations (at least 70 m) on the canyon walls. 

Theme 2: New ways to study submarine canyons: integrated programs, new technologies and coordinated monitoring efforts
Oral Presentation
Monterey canyon, turbidity current, grain size, push core facies