Mid-Continent Section

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A Structural re-evaluation of the Ardmore Basin


We are attempting to interpret the original style of rifting of the Precambrian Southern Oklahoma Aulacogen and its influence on Pennsylvanian tectonics and structural styles. In contrast to the historical interpretation of a single symmetric or asymmetric graben, we propose that the SOA consisted of two asymmetric half-grabens linked by a transfer zone. Detailed studies of the Sho-Vel-Tum and Eola-Robberson Fields were conducted to better understand the structural and tectonic evolution of the basin. Evidence from the Sho-Vel-Tum area suggests flexural-slip folding, into-the-hinge thrust faulting during transpression, and a decrease in accommodation space to the northwest along anticlinal hinges. Evidence from the Eola-Robberson area suggests transpressional deformation with significant vertical uplift. Key differences between the field studies suggest that the orientation of maximum compression varies, with Sho-Vel-Tum showing a stronger compressional component than Eola-Robberson. In a related study, gravity and magnetic data along with basement well penetrations were used to construct a basement structure map. These results suggest that the deformation styles are heavily influenced by the orientation of pre-existing faults where east-west faults are dominated by strike-slip movement, and northwest-southeast faults are dominated by transpression. This study supports the hypothesis that the initial rift geometry was composed of two asymmetric half-grabens.