--> Abstract: Comparison of the Fill of High- and Low-Sediment Supply-Incised Valley Systems, by Louis R. Bartek and Jeffery D. Warren; #90039 (2005)

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Comparison of the Fill of High- and Low-Sediment Supply-Incised Valley Systems

Louis R. Bartek and Jeffery D. Warren
University of North Carolina, Chapel Hill, Chapel Hill, NC

Examination of high-resolution seismic reflection data and core from the northeastern margin of the Gulf of Mexico (Mobile Incised Valley) and from the East China Sea (ECS) reveal the dramatic impact of variation of sediment supply on the fill architecture of incised valleys. The physiography of the ECS margin (very wide with perched deltas and a deep shelf edge) limits incision to the steeper segments of the perched deltas. Two of the top 4 rivers in the world, in terms of sediment supply, empty into the ocean across the ECS continental margin. This extremely high sediment flux rapidly filled the incisions of the ECS margin. The incisions were filled so rapidly with fluvial sediment that it is nearly homogeneous. This contrasts sharply with the highly compartmentalized fill of the Mobile Incised Valley (MIV). The sediment supply of the MIV system is a fraction of that of the ECS margin, so the fill of the incision occurred from the Lowstand through the Transgression, subjecting the incised valley to a range of depositional conditions as it was filled. During the transgression the incision was filled with an estuary that had a bayhead delta updip and a tidal inlet system downdip. The rate of sea level rise during the transgression was variable, which led to filling of the incision by retrograding parasequences. The rapid landward translation of the systems during intervals of rapid rise, followed by variable distances of progradation during slow rises compartmentalized the fill of the low sediment supply incised valley.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005