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

Abstract

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°S, 72.4°E, K = 244.7, A95 = 4.9°) 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°S, 346.7°E (K = 457.7; A95 = 4.3°). APW of 9.2° 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.