Jurassic paleopole controversy: Contributions from the Atlantic-bordering continents

Abstract

The Early-early Middle Jurassic and Early Cretaceous mean paleopoles for North America, Europe, South America, and Africa are very well grouped in appropriate continental reconstructions, but the intervening late Middle and Late Jurassic segment of the apparent polar wander path (APWP) is poorly defined and controversial. The available paleopoles, reconstructed for the partial opening of the central Atlantic Ocean, form a scattered grouping with no coherent age patterns, illustrating that they do not constitute a robust data set. Uncertainties in the reconstruction parameters between North America and Europe also play a role. However, excellent paleomagnetic results exist for tectonic elements near the margin of west Gondwana that are unlikely to have been significantly displaced with respect to cratonic Africa and South America. These results have not previously been used for APWP reconstructions, because local rotations are thought to have deflected the paleopoles in many cases. The inclinations of such results, however, can be used to determine a locus of paleopole positions. Paleopole loci for about 150 and 170 Ma were determined from results from Spain, Italy, Lebanon, and the Chilean Andes, and these were rotated with appropriate parameters to give locus intersections in North American coordinates. A late Middle Jurassic (early Callovian) best estimate of the paleopole in North American coordinates is located at about lat 70°N, long 135°E, and a Late Jurassic (Kimmeridgian) best estimate is located at about 70°N, 155°E. The resulting Jurassic-Early Cretaceous APWP follows roughly the 70th parallel, passing through the middle of the scattered individual paleopoles from the cratonic parts of the Atlantic-bordering continents.