Rock magnetic evidence for inclination shallowing in the early Carboniferous Deer Lake Group red beds of western Newfoundland

Abstract

SUMMARY A paleomagnetic and rock magnetic study of the Carboniferous Deer Lake Group red beds of Newfoundland was performed to detect and correct for inclination shallowing. Results indicate a primary remanence carried by magnetite, with a mean direction of D = 179.7 ◦ , I = 33.7 ◦ , α95 = 7.2 ◦ which corresponds to a paleopole position of 22.2 ◦ N, 122.3 ◦ E,A95 = 7.6 ◦ . Correcting the inclination using anisotropy of anhysteretic remanence and the measured individual particle anisotropy gives a corrected direction of D = 178.8 ◦ , I = 50.9 ◦ , α95 = 6.3 ◦ corresponding to a paleopole position at 8.4 ◦ N, 122.7 ◦ E, A95 = 7.2 ◦ . This correction is larger than that of other red beds from the Maritime Provinces of Canada, but is consistent with paleoenvironmental reconstructions, placing North America in a more arid climate zone. Our inclination-corrected results have important implications for this portion of North America’s apparent polar wander path and suggest a correction is needed for other red bed-derived APWPs. We have determined the range of flattening factors f , defined as the proportionality constant between the tangents of the measured (I m) and field (I o) inclinations, tan(I m) = f tan(I 0), from this study and previous inclination correction studies to estimate inclination corrections. Using the range of haematite f factors observed in this study to correct the Neogene red bed inclinations from the Vall` es-Pened` es Basin (NE Spain) yields inclinations consistent with the known geomagnetic field inclination in the Neogene, thus indicating that the range of f factors reported here may be used to estimate the magnitude of inclination shallowing in red beds.