STRATIGRAPHIC PATTERNS IN AN ACTIVE FORELAND BASIN, DESMOINESIAN STRATA OF THE ARKOMA BASIN, ARKANSAS

This study investigates sedimentation patterns of Desmoinesian strata within the Arkoma Basin, Arkansas, which formed as a result of the collision between Laurasia and Gondwana during the Pennsylvanian, a time period also known for major glaciations.

From existing geologic maps, we correlated successions of sand, shale, and coal beds between the study area and the type sections of the Hartshorne, McAlester, Savanna, and Boggy formations around McAlester, OK, about 150 km to the west. With help of high-resolution LIDAR data, we constructed a composite stratigraphic section from Mt. Magazine and tied it to our regional correlations. Paleoflow measurements and detrital zircon samples were collected within the area.

Facies are interpreted to represent shallow marine, deltaic, fluvial, and paludal environments of late-stage Arkoma Basin fill, corroborating previous investigations. Vertical facies trends are remarkably consistent across the entire 150 km transect and their cyclic nature resembles cyclothems, assigned to glacio-eustatic baselevel variations. Correlations confirm that the youngest strata in Arkansas likely belong to the Boggy Formation, whose basal part forms a continuous, mostly fluvial sandstone on top of the more marine Savanna Formation. Paleoflow directions indicate basin axial flow from east to west, with some input from the north. Preliminary detrital zircon U-Pb data indicate an Appalachian provenance within the Savanna Formation and units below. Distinctive Paleoproterozoic (ca. 2.1 Ga) and Neoproterozoic (ca. 0.55-0.7 Ga) age modes within the lower Boggy Formation are interpreted to reflect the arrival of (peri-)Gondwanan-derived sediment in the uppermost basin fill. These data suggest drainage reorganization from dominantly northeastern (Laurentian) sediment sources to a mixture of northern and southern sources in the shallow parts of the basin, indicating that both tectonics and glacio-eustacy influenced the Desmoinesian strata in this area.