The origin of Crowley's Ridge, northeastern Arkansas: Erosional remnant or tectonic uplift?

Abstract

The geomorphology of Crowley's Ridge, apparent Quaternary reactivation of the ridge-bounding faults, and orientation of the faults to the present stress field suggest that the faults bounding Crowley's Ridge and the western margin of the Reelfoot rift may be seismogenic. Fifteen high-resolution seismic reflection lines were acquired across and adjacent to the margins of Crowley's Ridge to test the hypothesis that Corwley's Ridge is fault bounded. Eleven of the reflection lines were 24-channel Mini-Sosie data with 1-sec record length and four lines were 24-channel shotgun-source data with 0.25-sec record length. Nine lines traversed the margins and adjacent areas of the northern segment of the ridge near Jonesboro, Arkansas, and the other six were located south of Jonesboro on the southern segment. The reflection data show that Paleozoic through Eocene Wilcox sections have been uplifted beneath Crowley's Ridge from 60 to 30 m across ridge-bounding faults. However, Eocene or Pliocene-Pleistocene near-surface strata appear to be displaced a maximum of 7.5 m. Based on reflection and geomorphologic data, we believe that reactivation of the bounding faults of Crowley's Ridge occurred concurrently with and strongly influenced Wisconsin denudation of the Mississippi valley.