Paleomagnetism of the Dewey Lake Formation (Late Permian), northwest Texas: end of the Kiaman superchron in North America

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Abstract
The remanent magnetization of red beds of the Late Permian Dewey Lake Formation from northwest Texas was investigated using thermal, chemical, and alternating field demagnetization. After removal of a small present‐day viscous overprint, the Dewey Lake shows univectorial decay of the remanence revealing a dual‐polarity characteristic direction of D = 152.4°, I = −11.1°, k = 39.5, α95 = 5.9°, N = 16 sites. Three polarity transitions were observed defining at least four polarity zones. The observed polarity zones are roughly layer parallel and may correlate with the Illawarra magnetozone at the end of the Kiaman. If this is so, K‐Ar age determinations of an interbedded ash layer (Kolker and Fracasso, 1985) suggest that the Kiaman Superchron ended before 251±4 Ma. The paleopole, located at 51.4°N–126.2°E, confirms the reliability of previously reported Late Permian poles from southwest United States, which fall significantly off the Late Permian segment of the paleomagnetic Euler pole (PEP) track of Gordon et al. (1984). This implies that a more segmented set of small circles is required to model the North American apparent polar wander path, diminishing the usefulness of the PEP method.