HR: 08:15h
AN: OS51A-02    [PDF]
TI: Continental-Margin Response to Sea Level: Theory and Experiment
AU: * Swenson, J
EM: jswenso2@d.umn.edu
AF: Department of Geological Sciences, University of Minnesota Duluth, 1114 Kirby Dr., Duluth, MN 55812 United States
AU: Paola, C
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455 United States
AU: Sheets, B
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455 United States
AU: Strong, N
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455 United States
AU: Kim, W
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455 United States
AU: Pratson, L
AF: Earth and Ocean Sciences, Duke University, 103 Old Chemistry, Durham, NC 27708 United States
AB: We present the results of theoretical and experimental studies on the stratigraphic response to high-amplitude eustatic sea-level cycles. Our theoretical work focused on the development of three-dimensional, integrated-morphodynamic models of shelf-clinoform response to eustatic cycling and the corresponding development of stratigraphic sequences. In our models, which treat the shoreline as a dynamic moving boundary, characteristic floods and coastal storms, of specified magnitude and intermittency, drive long-term evolution of the coupled fluvial and shallow-marine sediment surfaces. Clinoform behavior and overall margin morphology are sensitive to the relative efficacy of fluvial and shallow-marine sediment dynamics. The interplay of eustasy with large, frequent coastal storms generates compound clinoforms with broad, strongly interfering shelf environments and relatively small, highly three-dimensional fluvial systems. Such storm-dominated clinoforms develop significant phase shifts between the shoreline and the shelf edge (clinoform rollover) that affect the timing of sediment delivery to the deep marine and overall growth of the margin. Phase shifting decreases with increasing flood frequency and magnitude and, by extension, the transition to fluvio-deltaic sedimentation. In the experimental study, which we performed in a subsiding-floor basin at St. Anthony Falls Laboratory, we analyzed the stratigraphic response to both isolated and superimposed eustatic sea level cycles in a passive-margin setting. The interplay of subsidence and high-amplitude sea level cycling generated a complex stratigraphic architecture consisting of a series of stacked shelf-slope clinoforms. We measured the shoreline response, the partitioning of sediment between fluvial and marine environments, and the timing and nature of sequence-boundary formation.
DE: 3022 Marine sediments--processes and transport
DE: 3045 Seafloor morphology and bottom photography
DE: 4219 Continental shelf processes
DE: 4255 Numerical modeling
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting