Simms, Alexander Ray¹, John B. Anderson¹, Patrick Taha¹, Antonio Rodriguez² 
(1) Rice University, Houston, TX 
(2) University of Alabama, Tuscaloosa, AL

ABSTRACT: Going Beyond the Tripartite Model of Incised Valley Fill

Early incised valley facies models center around a ²tripartite² fill consisting of fluvial, estuarine, and marine facies. Most of the incised valleys that formed during the Last Glacial Maximum (18,000 years BP) across the Northern Gulf of Mexico fit this model; however, many, such as the Brazos and Rio Grande incised valleys, do not. The Brazos and Rio Grande systems deviate from the "tripartite" model in that they lack estuarine facies and often grade into transgressive deltas. We suggest a modification of the classic "tripartite" model of estuary-incised valleys to include fluvially dominated incised valleys such as the Rio Grande and Brazos. We further propose to name the end members of this incised valley model overfilled and underfilled with respect to fluvial sediments. This classification allows generalities to be drawn from the simple identification of the proportion of fluvial fill.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.