Paleomagnetism of the Moenave Formation: Implications for the Mesozoic North American apparent polar wander path

Abstract

Previous syntheses of the Mesozoic North American apparent polar wander (APW) path have suggested the presence of a sharp corner or cusp (the J-1 cusp) in the Late Triassic to Early Jurassic. Paleomagnetic data from the Lower Jurassic (Sinemurian) Moenave Formation clarify details of this important feature in the APW path. A total of 220 oriented cores were collected from 31 levels in four stratigraphic sections of the Moenave Formation in northern Arizona and southern Utah. Thermal demagnetization in multiple steps, generally between 600 and 660 OC, was successful in revealing the characteristic component of natural remanent magnetization at 23 sites. The paleomagnetic pole is lat = 58.2ON, long = 51.9OE; radius of 95% confidence (ag5) = 4.5'. The Moenave pole position verifies the existence of the J-1 cusp, and thus supports the use of paleomagnetic Euler pole analysis in modeling the pattern of APW.