Abstract: Pennsylvanian Sequence Stratigraphy of the Arkoma Basin
Allan P. Bennison
Sequence stratigraphy for tectonically active foreland basins, such as the Arkoma Basin, differs appreciably from that now widely accepted for relatively passive marginal basins. Owing to its greater geographic confinement, sediments can be stacked above sea level, even in the trough area, until a loading threshold is reached and/or a rise in global sea level results in additional accommodation for sediments.
Another important difference is that an orogenic belt maintains its high relief and continues to contribute sediments during major flooding of the continental shelf, that diminishes sediment influx from that source. This results in a cratonward shift of the basinal axial deposits and a sediment stacking in the basinal area and orogenic border four or more times that on the cratonic shelf.
This foreland basin sequence is commonly unconformity bounded. Its initial deposits are usually those of the transgressive system tract, succeeded in turn by the highstand, lowstand and finally the forced regressive system tracts. This sequence is commonly interrupted by renewed tectonic and glacio-eustatic forced sea level changes.
The transgressive system tract is usually accomplished within one parasequence, owing to an accelerating rise in sea level. After a transgression, a highstand of sea level may continue throughout two or more eustatic fluctuations of sea level. In an idealized sequence, this phase is followed by basin filling, consisting of lowstand deposits of shallow marine to onshore regressive fluvial deposits.
AAPG Search and Discovery Article #90957©1995 AAPG Mid-Continent Section Meeting, Tulsa, Oklahoma