EarthRef.org Reference Database (ERR) -- Beck 1999

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 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. ¿ 1999 American Geophysical Union 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 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. ¿ 1999 American Geophysical Union