BEATY, SCOTT, Chevron, USA, Midland, Texas; W. LYNN WATNEY, Kansas Geological Survey, Lawrence, Kansas; and ALEX MARTINEZ, Exxon Exploration Company, Houston, Texas

Abstract: Analysis of Structural Controls on the Development of the Upper Pennsylvanian Tonganoxie Incised Paleovalley System of Northeast Kansas

The paleotectonic setting of the Tonganoxie Sandstone (Upper Pennsylvanian, Virgilian) incised valley system in northeast Kansas was analyzed using isopach maps of the stratigraphic interval containing a paleovalley-fill and lineaments maps based on presentday Precambrian basement and potential fields data. Because structure maps of Upper Pennsylvanian strata reveal little about the structural framework that influenced paleovalley erosion and sedimentation, isopach maps were used to detect subtle changes in local topography due to concurrent structural movement. Previous studies along the eastern portion of the paleovalley system identified a large trunk valley with smaller tributary valleys exhibiting rectilinear drainage.

Persistent linear thickness trends correspond closely to trends of mapped lineaments, suggesting that basement reactivation influenced the location of paleovalley development. Variations in thickness of these stratigraphic intervals are related to differential subsidence within distinct multi-km scale structural blocks with boundaries oriented predominately NW-SE and SW-NE. The rectilinear drainage pattern of the Tonganoxie paleovalley was the result of movement along the structural blocks. The apparent link between present-day basement heterogeneity and earlier structural developments suggests that reactivation along pre-existing basement faults has been an episodic process in the northeast Kansas region. Exploration for incised valleys should consider regional mapping of appropriate stratigraphic intervals and related basement information to discern structural blocks and possible influence on valley incision.

AAPG Search and Discovery Article #90921©1999 AAPG Mid-Continent Section Meeting, Wichita, Kansas