Paleomagnetism of the Upper Ordovician Juniata Formation of the central Appalachians revisited again
Two components of magnetization were isolated in the Upper Ordovician Juniata Formation sampled in the area of the Pennsylvania salient. The thermally distributed, reversed polarity B component was most likely acquired during Alleghenian deformation, and although it is poorly grouped, it is similar to other Appalachian synfolding magnetizations. The pre-Alleghenian age C magnetization is entirely of normal polarity and shows a difference in declinations between the mean magnetizations isolated on the northern and southern limbs of the salient of 24° ± 23°. This anomaly is consistent with the sense and magnitude of declination anomalies observed in pre-Alleghenian magnetizations isolated in other throughgoing Appalachian red beds of Silurian, Devonian, and early Carboniferous age. The mean inclination of -44.7° suggests a paleolatitude of about 26°S for the central Appalachians in the Late Ordovician. This paleolatitude fits a trend of southward motion of North America from the Ordovician to the Early Devonian, followed by northward drift through the remainder of the Paleozoic.
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Also Published In
- Journal of Geophysical Research