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Analysis of Depositional Architecture & a 3-D Simulation Study with Boundary Conditions of a Pennsylvanian Outcrop Exposed from Pikeville, Kentucky

Chatterjee, Sumanta K.1; Kendall, Christopher G.1
1 Geological Science, University of South Carolina, Columbia, SC.

3-D numerical modeling of sedimentary outcrops involves the detailed analysis of architectural elements that constitute the framework of any depositional system. These elements are key to interpreting channel behavior and other physical conditions that persisted millions of years ago. The study area at Pikeville in Eastern Kentucky exposes a Pennsylvanian age outcrop along US 23 and belongs to the Breathitt Group.

The primary data for this project is a collage of images systematically acquired from the road cut cross section. The analysis of the architectural elements and lithofacies, and the interpretation of depositional setting of the outcrop was determined from a photomosaic and indicated a fluvio-deltaic setting. This was expressed by several episodes of delta front channel migration and reoccupation, the formation of an incised valley and its fill, and the varying autocyclic and allocyclic conditions during the sediment accumulation in the section.

A conceptual 3-D model was built on the basis of inferred facies relationships within the outcrop. The project aims to simulate the depositional setting of the outcrop using a 3-D computer model constrained by the physical parameters inferred from the outcrop, analogous channels with similar depositional settings and acceptable flume data. Each of the architectural elements has been systematically extracted from the section in the reverse order of their accumulation. They have been reassembled chronologically, and linked to both the physical processes that were active in the depositional setting and the approximate time span involved. The time spans of the depositional events responsible for each individual element or groups of elements are essentially unknown, but estimates of the time range involved for each event was determined on the basis of character of the architectural elements in the outcrop and information from modern analogous systems. The systematic approach of back-stripping and 3-D simulation enable the low and high frequency signals to be determined from the interpreted physical processes responsible for changes in character in the elements of the section.

Besides accounting for different processes taking place within the depositional system, the project introduces and seeks to test relevance of a new parameter-valley angle, with the help of process based simulated models

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009