Paleomagnetism of the Cambro‐Ordovician Arbuckle Group and associated deposits in the southern Oklahoma Aulacogen: Evidence for block rotations

The magnetization in hydrocarbon‐impregnated Arbuckle Group limestones from the southern margin of the Southern Oklahoma Aulacogen (Limestone Hills) is secondary and resides in magnetite. The magnetization (Declination/Inclination=128°/2°, α₉₅=7.6°, k=79) fails a fold test and is post Pennsylvanian. The corresponding pole position (146°E, 30°N), however, does not coincide with the post‐Pennsylvanian Apparent Polar Wander Path (APWP). Some Permian speleothems that fill caves in these rocks contain magnetizations that are also anomalous. Shallow remanent inclinations from the folded limestones and speleothems suggest that the most likely time of remanence acquisition was the Permian. The directions are at least 30° in declination from the expected directions based on the inferred ages of the magnetizations. This discrepancy can be explained by a horizontal counterclockwise rotation, consistent with left‐lateral wrench faulting, during deformation of the aulacogen.