Paleomagnetism of the Upper Devonian Catskill Formation from the southern limb of the Pennsylvania Salient: Possible evidence of oroclinal rotation

Abstract

Multiple components of magnetization were isolated in the natural remanent magnetization of samples of the Upper Devonian Catskill Formation red beds taken from the southern limb of the Pennsylvania Salient. The dominant, thermally distributed component (SF), previously thought to predate folding, is demonstrably synfolding in origin. The mean direction for SF based on data from the current study and a previous study is Declination/Inclination = 161.6°/7.9°, a95 = 3.9° (pole position 127.3°E, 43.1°N, A95 = 3.1°, N = 14 sites). Although the remagnetization is clearly synfolding in most areas, the relative ages of folding and remagnetization vary locally. A subordinate high unblocking temperature component (HT) has a mean tilt corrected direction of 160°/36°, a95 = 16° (pole position 123.5°E, 26.1°N, A95 = 15.4°, n = 7 samples). Comparison of HT with the prefolding magnetization isolated in the northern limb of the salient suggests that the paleolatitude of this part of North America was about 16°S and that part of the curvature of the salient was acquired during orogenesis.