3-D Mapping of Vertical and Lateral Facies Heterogeneity of a Compound, Tributive Incised Valley, Turonian Ferron Sandstone, Notom Delta, South-Central Utah
Hilton, Benjamin D.; Bhattacharya, Janok; Khan, Shuhab; Griffen, Cameron; Biber, Kivanc
Incised valley systems are important for sequence stratigraphic and exploration purposes. The tributary components of these systems inherit complicated, self-similar, plan-view morphologies from the drainage networks that form them. Incised valley depositional models often exclusively focus on fill facies within larger trunk valleys and either ignore or poorly document facies within smaller tributary valleys. The Notom Fluvio-Deltaic complex, a component of the Turonian (Late Cretaceous) Ferron Sandstone Member of the Mancos Shale Formation, outcrops along Nielson Wash, Utah, and provides the opportunity to study in 3-D, facies heterogeneity of compound, incised valley fills, including both trunk and tributive components. Using traditional field methodologies (56 measured sections) and remote sensing (areal LiDAR survey), several objectives have been completed: 1. previous 2-D outcrop work/ interpretations have been updated and described in 3-D space, 2. Plan view maps show north east oriented channel belts with both braided and meandering plan view patterns within their respective valley fills, 3. younger cut & fill sequences (unaccounted for in previous studies) are documented, and 4. Interpretation of remnant terraces/interfluves suggest high diachroneity associated with the higher and lower order erosion surfaces that form the composite sequence boundary. Vertical facies variation shows more confined valleys to be more sand dominated while less confined valleys are muddier as predicted by traditional fluvial sequence models; however, fill styles, and degree of sand-body amalgamation varies significantly for each cut and fill episode due to changes in hydrologic conditions, distance to estuarine/tidal processes, and river style (braided or meandering). Since current models of these systems oversimplify natural system complexity, and because tributive valleys have had less scientific attention in the literature relative to trunk valleys, detailed outcrop-based studies are needed to understand facies heterogeneity.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013