IMPLICATIONS OF NEW PALEOMAGNETIC DATA FROM THE REDDING SECTION, EASTERN KLAMATH TERRANE

Previous paleomagnetic data from Devonian through Jurassic rocks of the Redding Section, southeastern Klamath Mountains, have been interpreted in various, partly conflicting ways. Multiple components of remanent magnetization are widespread, hindering reliable inference of primary directions in many cases. Previously published studies are in general agreement that the Eastern Klamath Mountains have experienced little or no poleward (latitudinal) transport with respect to the North American craton. However, what remains controversial is the nature and significance of large rotations (>90°) manifest in the paleomagnetic declination. An unresolved question is whether these anomalous declinations are spatially uniform (implying rigid-body rotation), or spatially variable (implying oroclinal deformation). New sites in siltstones and mudstones of the late Carboniferous Baird Fm. yield well-defined ChRM directions associated with both magnetite and hematite. These results are of reversed polarity as expected for deposition during the Kiaman polarity chron and have inclinations (-10° to -20°) expected for this part of the North American craton in the Carboniferous. Strike-line unfolding (plunging fold axes are rare) produces declinations varying from 220° to 160°. This suggests variable rotations of 25° to 85° CW. New sites in the Upper Triassic Hosselkus Limestone yield variable data depending on the site and stratigraphic levels sampled. A pre-folding, dual polarity remanence was found at 2 sites that show exceptionally large rotations (120° CCW). Other sites in the Hosselkus have a post-folding, single (Normal) polarity remanence that matches a previously reported overprint of Jurassic age. New sites in the early Permian McCloud Limestone (Lake McCloud area) show reverse polarity and cratonic inclination, but very large rotations (>150° CW). Overall, general correlation between local structural trends (i.e., bedding strike) and declination implies vertical axis oroclinal bending, although some sites fit the pattern poorly and may reveal more complicated deformation histories. In any case, uniform rigid body rotation of the Redding Section subterrane of the Eastern Klamath Terrane can be definitively dismissed.