干旱区生态环境知识资源中心

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 degrees, I = 33.7 degrees, alpha(95) = 7.2 degrees which corresponds to a paleopole position of 22.2 degrees N, 122.3 degrees E, A(95) = 7.6 degrees. Correcting the inclination using anisotropy of anhysteretic remanence and the measured individual particle anisotropy gives a corrected direction of D = 178.8 degrees, I = 50.9 degrees, A(95) = 6.3 degrees corresponding to a paleopole position at 8.4 degrees N, 122.7 degrees E, A(95) = 7.2 degrees. 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 Vallees-Penedes 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.