Jurassic and Cretaceous apparent polar wander relative to South America: Some tectonic implications

Late Mesozoic apparent polar wander (APW) with respect to stable South America has been difficult to define. It appears that this observation has a simple explanation; very little APW occurred and none at all during a 50 m.y. period (165 to 115 Ma). It is possible to compute a "stillstand" pole for this interval (88.8 degrees S, 72.4 degrees E, K = 244.7, A(95) = 4.9 degrees) from five, reliable studies comprising a total of 523 sites. A second stillstand of much shorter duration (70-80 Ma) is defined by four poles (52 sites); this is located at 80.8 degrees S, 346.7 degrees E (K = 457.7; A(95) = 4.3 degrees). APW Of 9.2 degrees occurred during the interval 115-80 Ma. A comparable stillstand is found in the North American record [e.g., Van Fossen and Kent, 1992]; this has a similar degree of scatter (K=421) and spans at least 36 m.y. (124 to 88 Ma). Thus North America and South America both were rotating due westward during a large part of the Cretaceous; this has some important implications for global tectonics.