Quantifying Channelized Submarine Depositional Systems from Bed to Basin Scale

William Lyons, Ph.D., 2004
John Grotzinger and David Mohrig, Advisors

In this thesis, I employ 3-D seismic data and outcrops to study turbidites from bed to basin scales. Using seismic data from the Fisk Basin, Gulf of Mexico, I develop a method to estimate the timeframe over which sedimentation and subsidence come into equilibrium within a basin. Basin-specific equilibrium times are found to range from 4.6x105 years to 2.0x105 years, depending upon depositional architecture. Such equilibrium times are critical; they define the threshold at which we can differentiate autogenic and allogenic stratigraphic signals. At the scale of turbidite beds, grainsize analyses of sediment samples from the Capistrano Formation, San Clemente, California, reveal the potential for misinterpretation that arises when deposits are studied without consideration of sedimentation dynamics. Simple bed shear calculations and Froude scaling indicate that, in contrast to earlier work, the coarse Capistrano Formation sediments are consistent with classical muddy, low-density turbidity currents. Finally, at the scale of amalgamated turbidite beds, outcrop mapping and aerial photography of the Zerrissene Turbidite System, Namibia, provide a measure of the lateral and vertical continuity of a deepwater turbidite system. The extensive continuous exposure of the Zerrissene reveal that correlation lengths of these systems can exceed 1.5 km.