Rebecca A. Scheppy¹, Diane L. Kamola¹, J. Douglas Walker¹, Ross A. Black²
(1) University of Kansas, Lawrence, KS
(2) University of Kansas, Lawrence

Abstract: A three-dimensional analysis of the internal architecture of an incised valley: Desert Member, Blackhawk Formation, Book Cliffs,Utah

Complex compartmentalization of incised valley fills complicates the prediction of rock property distribution patterns within reservoirs. Quantifying that compartmentalization is important in understanding the variable reservoir quality of incised valley fills. Detailed fieldwork, digital photogrammetric mapping, and GPS are integrated to develop a 3-D orthomodel of 5 canyon wall transects within an area of ~1km2. The orthomodel can then be used for quantifying facies organization and stratal architecture to better predict rock property distribution in incised valley fill.

The Desert Member of the Blackhawk Formation, Book Cliffs, eastern Utah, contains a well-exposed sequence boundary overlain by a ~20m thick succession of incised valley fill strata. Incised valley deposits in Tuscher Canyon are visible almost continuously both parallel and perpendicular to depositional dip in these 5 canyon wall transects. The valley fill is divided into 2 distinct sections, separated by a flooding surface overlying a thin coal. This surface is interpreted as a parasequence set boundary. The lower half of the fill is dominated by a multistory sandstone composed of three stages (parasequences?) with varying amounts of tidal influence. Above the parasequence set boundary the fill contains laterally continuous, thinly bedded, single-story sandstones separated by laterally extensive mudstones and siltstones. The 2 sections may reflect a change (increase) in the rate of relative rise in sea level. The 3-D model, generated by Erdas Imagine and GIS software, shows the lateral continuity of the individual stratal elements within the valley fill.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana