Detailed demagnetization experiments isolated a characteristic remanent magnetization in ten stable sites from the upper Cretaceous Winthrop and Midnight Peak Formation in the Methow-Pasayten belt of north-central Washington. This remanence agrees best between opposite limbs of a fold (the Goat Peak syncline) when corrected for 46% of tilt. This is consistent with magnetization acquired during deformation. Synfolding magnetization may have been facilitated by a thermo-chemical event associated with synkinematic intrusions along the axis of folding. The mean direction (D=12.0°, I=61.1°, Alpha-95=4.8°) is highly discordant with respect to the expected direction for north-central Washington. This discordance points to about 1,400 km of poleward transport and 48 of clockwise rotation between 93 and 45-48 Ma.
Geophysical Research Letters
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Published by American Geophysical Union
Burmester, Russ R.; Beck Jr., Myrl E.; and Granierer, Julian L., "Cretaceous Paleomagnetism of the Methow-Pasayten Belt, Washington" (1986). Geology Faculty Publications. 27.