Date of Award
Master of Science
Roy Van Arsdale
Ongoing geologic research in the southern Mississippi Embayment has documented several zones of Quaternary paleo-seismicity trending NW-SE along the Proterozoic Alabama-Okalahoma Transform Zone. Faulting in this region offsets Pleistocene to Holocene alluvial terraces in the Saline River Valley. 20 km to the south, Quaternary terraces in the Ouachita River Valley also suggests a local, tectonic influence due to their principle distribution to the northeast. This asymmetry is evidence for tilting to the southwest throughout the Quaternary. This research tests the hypothesis that the Ouachita River Valley has been tilted southwestward and quantifies deformation of terraces within the valley. Eroded material from these terraces was restored through creating a topographic envelope map using elevations of tributary drainage divides crossing each tread. Individual treads were delineated from this envelope map and deformation was characterized on tread surfaces with best-fitting planes, residual contour maps, and topographic profiles. Anomalous elevations and slopes were assessed for temporal inter-terrace trends. Terraces were correlated by similar soil development as a proxy for age. One or more events has tilted (marine isotope stage V and VI) Prairie Complex I and II terraces (slope directions = 198° and 203° respectively) ~80° (clockwise) southwest from the slope direction of the active floodplain (123°). Slope angles of the Prairie Complex I (0.09° SW) and II (0.084° SW) terraces are an order of magnitude larger than the active floodplain (0.008° SE).
dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.
Gamble, Eric David Stewart, "Tectonic Deformation of Quaternary Terraces in the Ouachita River Valley in South-Central Arkansas" (2016). Electronic Theses and Dissertations. 1511.