Rotation of the Colorado Plateau

Consistent displacement of its paleomagnetic pole positions suggests that the Colorado Plateau has rotated with respect to cratonic North America. Since pole positions derived from the Colorado Plateau form a significant portion (35%) of the pre‐Cretaceous population of North American paleomagnetic data, the rotation has significant impact on the continent's data base. Comparison of paleopoles from nearly coeval strata on and off the plateau shows that the plateau pole positions are always displaced clockwise from non‐plateau counterparts, in amounts varying from 9° to 14°. The time periods for which such comparisons are possible are the Late Triassic, the Early Triassic, the Late Pennsylvanian, and the Middle to Late Devonian. Other time periods contain data which appear to be consistent with a clockwise displacement of plateau pole positions, but poor age control, rapid apparent polar wander, and late Paleozoic remagnetization all hamper comparisons. Only one of the time periods examined, the Permian, does not show net rotation of the plateau. Observation of the rotation of the plateau has been obscured by the fact that a great many of the plateau poles are from times of rapid apparent polar wander (APW), and the displacement effected by rotation parallels the major APW trends. This renders the discrepancy of plateau poles relatively inconspicuous and is only readily observable between poles from the same age strata. The rotation of the plateau has particular impact on the early and middle Mesozoic paleopoles, to which the plateau had contributed heavily. In particular, for the Late Jurassic, plateau poles are the only data available for the analysis of western North America allochthonous terrane movements.