2003 Seattle Annual Meeting (November 2–5, 2003)

Paper No. 14
Presentation Time: 5:00 PM


PAOLA, Chris1, MARTIN, John1, MOHR, Jere2, PRATSON, Lincoln3, SHEETS, Ben1, STRONG, Nikki1 and SWENSON, John4, (1)Geology & Geophysics, Univ of Minnesota, 310 Pillsbury Drive SE, Room 108, Minneapolis, MN 55455-0219, (2)Department of Geological Sciences, Univ of Minnesota, Duluth, 224 Heller Hall, 1114 Kirby Drive, Duluth, MN 55812, (3)Earth and Ocean Sciences, Duke Univ, 103 Old Chemistry, Durham, NC 27708-0230, (4)Large Lakes Observatory and Department of Geological Sciences, Univ of Minnesota Duluth, 10 University Drive, Duluth, MN 55812, cpaola@tc.umn.edu

We report the results of two experimental studies of clinoform dynamics carried out at St Anthony Falls Laboratory. The first , in our experimental subsiding-floor basin (“Jurassic Tank”), was designed to study clinoform response to isolated and superimposed fluctuations in eustatic base level. The experiments allow us to measure (1) formation of sequence boundaries, (2) partitioning of sediment between the fluvial and offshore systems, (3) partitioning of sediment between externally supplied and valley-wall sources, (4) complete stratal architecture produced by the cycles, (5) development of a composite shelf-slope topography through superposition of a series of stacked shorelines, and (6) the composite “time stochastic” nature of the main erosional and depositional surfaces produced during the cycles, the result of the strong interplay between externally forced (allogenic) and internally generated (autogenic) variability. Net erosion and deposition are the result of small overall imbalances between highly variable instantaneous rates of erosion and deposition.

The second set of experiments show how fluvial aggradation during clinoform migration is controlled by the relative ability of the system to clear sediment from the toe of the clinoform. The clinoform toe acts as a critical point for sediment transport (“chokepoint”); small changes in sediment flow there can ultimately control the entire upstream behavior of the clinoform system.