NORTH-AMERICAN JURASSIC APPARENT POLAR WANDER - THE ANSWER FROM OTHERCONTINENTS

Jurassic paleomagnetic data from North America, which come essentially from the NE and SW USA, outline two contradictory apparent polar wand er paths (APWPs). Following Besse and Courtillot (J. Geophys Res., 96: 4029-4050, 1991), we derive synthetic APWPs for North America based o n data from other Atlantic-bordering continents without resorting to t he North American data themselves. We discuss variations in the data b ases and in the kinematics used for the reconstructions, and find that a set of some 12 predicted APWPs is well constrained to lie within a band of 5-degrees half-width along 75-degrees-N latitude. The main unc ertainties occur along the track (i.e. longitude) but not perpendicula r to it (i.e. latitude). We conclude that, as has been suggested befor e, most of the Jurassic North American data show the effect of either partial remagnetization in a recent field or tectonic rotation, and th at, until more reliable data become available, the synthetic transferr ed paths from other Atlantic-bordering continents offer more reliable estimates of Jurassic North American paleogeography and polar wander.