Paper No. 23
Presentation Time: 9:00 AM-6:00 PM
PARAMETERS CONTROLLING STRATIGRAPHY OF A MIDDLE PENNSYLVANIAN INCISED VALLEY FILL IN EASTERN KENTUCKY
CHATTERJEE, Sumanta, Department of Earth and Ocean Sciences, University of South Carolina, Columbia, SC 29208 and COHEN, Arthur D., Department of Earth and Ocean Sciences, University of South Carolina, 701 Sumter Street, Columbia, SC 29208, schatterjee@geol.sc.edu
A dynamic forward stratigraphic model of an early Middle Pennsylvanian stacked channel complex near Pikeville, eastern Kentucky, simulated formative processes by quantifying different paleohydraulic and geologic parameters and events. The primary data came from a detailed outcrop analysis of geometries of architectural elements and interpretations of the depositional systems. The objective was to understand the processes that created an incised valley and their relative influence in controlling the behavior of channels filling the valley. For this purpose we developed a 3D perspective of the study area by comparing data from the outcrop with analogs and flume studies from the literature. With this information we investigated the sensitivity of different parameters to establish fundamental controls on observed basin stratigraphy. The resulting 3D stratigraphic model constrained our conceptual model and predicted the sediment distribution beyond the outcrop area.
Although many allocyclic and autocyclic factors were at play, the factors that were observed to be most significant in this study were base level, discharge, sediment supply, sediment accumulation rate, and stacking density. After the incised valley was formed, there was an overall increase in base level with time. At high discharge and sediment supply, channels showed varying sedimentation rates; whereas, those with medium discharge showed high sedimentation rates and sediment supply. On the other hand at low discharge the thickness of the channel elements was primarily controlled by sediment supply. Subsidence rates affected the downstream change in stratigraphy. The valley seemed to widen in response to base level fall. Change in stacking pattern from the bottom to the top of the valley fill was mainly controlled by increase in sedimentation rates and concomitant increase in base level. This resulted in higher channeling frequency and stacking density at the top of the incised valley fill.
