ROTATION OF THE COLORADO PLATEAU - AN UPDATED ANALYSIS OF PALEOMAGNETIC POLES

All available Jurassic, Triassic, and late Paleozoic paleomagnetic poles from the Colorado Plateau and stable North America are used to estimate the rotation of the Colorado Plateau relative to stable North America since Jurassic time. The paleomagnetic poles differ from those of our prior study [Bryan and Gordon, 1986] through the addition of seven recently published poles, the deletion of one pole, and the replacement of two others. We also improve on our prior analysis by omitting Cretaceous poles. From the systematic offset between plateau poles and stable North American poles we estimate rotation of the Colorado Plateau to be (95% confidence limits) clockwise, ∼1° larger than we found before. The null hypothesis of no systematic difference between plateau poles and stable North American poles can be rejected with a formally high level of confidence (99.99%). The hypothesis that the systematic differences between plateau and off‐plateau poles is as large as 10°, as proposed by several workers using fewer poles, can be rejected at an equally high level of confidence. Copyright 1990 by the American Geophysical Union.