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Using Alluvial Architecture to Define Stratigraphic Sequences in Foreland Basins, Upper Cretaceous Strata of the Kaiparowits Basin, Utah

Little, William W.
Brigham Young Universtiy-Idaho, Rexburg, ID

     As basin subsidence and eustatic sea level fluctuations each affect the production of accommodation space and can form similar vertical successions for a given locality, tectonic and eustatic models based on interpreted relationships between alluvial architecture and rates of accommodation production have been developed for Upper Cretaceous strata of the Kaiparowits Basin, south-central Utah to try and determine whether or not eustatic and tectonic effects can be differentiated from one another in a foredeep basin setting. These strata comprise three tectonically-generated second-order sequences that record migration of the Western Interior Foredeep axis as the Sevier Thrust Belt approached from the west. Each sequence consists of four parts that demonstrate distinctive styles of alluvial architecture associated with varying rates of basin subsidence and together make up an approximately 2 km-thick succession dominated by nearly continuous fluvial deposition. It is believed that regional distribution patterns defined by these changes in architecture, particularly for the capping unit of each sequence, can be used to distinguish between tectonic and eustatic forcing mechanisms. Such interpretations have significance in determining the placement of sequence boundaries in terrestrial successions of foreland basins.

 

AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah