--> Abstract: Net Pumping of Sediment Into Deep Water Due To Base-Level Cycling; #90063 (2007)

Datapages, Inc.Print this page

Net Pumping of Sediment Into Deep Water Due To Base-Level Cycling

 

Kim, Wonsuck1, Chris Paola1, John Martin2, Marty Perlmutter3, Frederick Tapaha4 (1) University of Minnesota, Minneapolis, MN (2) St Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN (3) Chevron Energy Technology Company, Houston, TX (4) New Mexico Institute of Mining and Technology, Socorro, NM

 

The general tendency for sediment supply to deep water to be maximized during eustatic fall and lowstand, and minimized during rise and high stand, is well established in the sequence-stratigraphy literature. Much less is known about the cumulative effect of repeated eustatic cycles on net deep-water sediment delivery. Here we investigate the possibility that repeated eustatic cycles can increase the net delivery of sediment to deep water averaged over several cycles, an effect we term sediment pumping. We present two sets of experimental results collected from the Experimental EarthScape (XES) and Delta basins at the St. Anthony Falls Laboratory, University of Minnesota. XES run in 2002 modeled the effect of slow and rapid base-level cycles on stratigraphic configuration under a passive margin type subsidence with constant water and sediment supply. Two Delta basin experiments in 2005 were run to address the effects of water and sediment supply variation with +90° and -90° phase shifts from the imposed base-level cycle on stratal development. These experiments provide clear examples of stratigraphic fluvial and marine facies partitioning driven by base-level change and coupled supply and base-level cycling, respectively. Combining data from these laboratory experiments (sliced sections and scanned topographic profiles) and a 2D geometric model, we find that net sediment pumping depends on (1) the relative timescale of the external perturbation to the basin equilibrium time, i.e., a ‘slow' or ‘rapid' base-level cycle, (2) the spatial subsidence pattern, and (3) the phase of sediment supply relative to eustatic variation. Slow base-level cycling results in a rather poor sediment pump, actually resulting in a smaller marine fraction compared to constant base-level conditions (i.e. no perturbation). A backtilting subsidence pattern produces a substantially stronger pumping than a foretilting geometry, and pumping is maximized when the sediment supply maximum occurs during eustatic falling stage or lowstand.

 

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