PALEOMAGNETISM OF CAMBRIAN CARLTON (COLBERT) RHYOLITE, ARBUCKLE MOUNTAINS

A previous paleomagnetic study of the Carlton (Colbert) Rhyolite in the Arbuckle Mountains indicated the upper part was remagnetized in the late Paleozoic (Elmore et al., 1998, GSL Spec Pub. 144, p. 9). Preliminary results also indicated that the rhyolite contains a Cambrian, possibly primary thermal remanent magnetization residing in magnetite. To test these previous results, and determine if a Cambrian magnetization could be isolated from the Carlton Rhyolite, additional samples were collected from the upper rhyolite in the East Timbered Hills. This work was facilitated by a recently completed study of the Carlton Rhyolite Group in the East Timbered Hills (Eschberger et al., 2014, OGS Guidebook 38, p. 143) which provided new information on the lithological variability within the unit. Our specimens were subjected to low temperature demagnetization (LTD) to remove any contamination by multi-domain magnetite. Five LTD steps removed between 2 and 21% of the natural remanent magnetization. Thermal and alternating field demagnetization indicates that some specimens contain a component with east-directed declinations and shallow inclinations which is similar to the previously reported Cambrian magnetization. Other specimens contain a component with south-directed declinations and shallow inclinations that is interpreted to be a result of late Paleozoic remagnetization. Some specimens contain both components. The demagnetization characteristics suggest both components reside in magnetite. Preliminary results indicate that the rhyolite is partially remagnetized although more analysis is necessary to determine if a primary or early Cambrian component can be isolated. Additional studies are currently underway to better define both components.