![]() ![]() We follow with an analysis of data from Adria, the promontory of Africa (Channell, 1996), and make the case that these independent data strongly bolster a new course in the understanding of Jurassic polar wander. Here we first present a brief updated historical overview of data used in reference APWPs and describe a desultory restudy of the Late Jurassic Morrison Formation (Fm.), a prominent source of Late Jurassic data for North America. The Jurassic apparent polar wander path (APWP) has long been controversial (Courtillot et al., 1994 Hagstrum, 1993 Kent & Irving, 2010), introducing critical uncertainties in the paleogeography of the major continents and relative movements of tectonic terranes. ![]() ![]() Key Pointsġ Introduction and Historical Perspective on Jurassic Polar Wander ![]() Finally, we provide paleocontinental reconstructions to describe examples of the bold signature that the monster polar shift left in the distribution of climate-sensitive sedimentary facies worldwide. We include a critique of published Jurassic paleomagnetic data that have been variably used in reference APWPs but that as a result of their low quality muted the real magnitude of the Jurassic monster shift. The implied high rate of polar motion of ~2.5°/Myr across the monster shift is compatible with maximum theoretical estimates for true polar wander. These paleopoles are found to be in superb agreement with independent igneous paleopoles from the literature across the so-called Jurassic monster polar shift, which in North American coordinates is a jump of ~30° arc distance from the 190- to 160-Ma stillstand pole at 79.5°N 104.8☎ to a 148 ± 3.5-Ma pole at 60.8°N 200.6☎ defined by four Adria sedimentary paleopoles and the published Ithaca, Hinlopenstretet, and Swartsruggens-Bumbeni igneous paleopoles. We instead assembled an updated set of Jurassic paleopoles from parauthocthonous Adria, the African promontory, using primary paleomagnetic component directions derived from stratigraphically superposed intervals and corrected for sedimentary inclination error. Here we show from a restudy of two subdivisions of the Late Jurassic Morrison Formation at the classic locality at Norwood on the Colorado Plateau that the derived paleopoles reflect variable overprinting probably in the Cretaceous and are of limited value for apparent polar wander determination. Jurassic paleomagnetic data from North America have long been contentious, generating ambiguities in the shape of the global-composite apparent polar wander path. ![]()
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