Folding at two different scales of the Paradox anticline in the Ordovician Cool Creek Formation, Arbuckle Group, Slick Hills, southwestern Oklahoma: A paleomagnetic fold test study.
The carbonates in the Cambro-Ordovician Arbuckle Group, part of the southern Oklahoma aulacogen, has been the subject of previous paleomagnetic studies with a focus primarily on their origin of the magnetizations. Most previous studies indicate late Paleozoic magnetizations that reside in hematite. However, Elmore et al. (1988) conducted a paleomagnetic study of the Arbuckle Group carbonates from the Slick Hills area utilizing six sites from a north-plunging tightly folded Paradox anticline. Alternating field and thermal demagnetization results from their study indicated a post-tilting remanence that resides primarily in magnetite. Also, based on the difference between the observed and expected remanence directions, they suggested a possible 30° block rotation. As a continuation of their work, this paleomagnetic study was conducted to corroborate the observed 30° rotations utilizing more sites from the Paradox anticline and the use of a more sensitive 2G Cryogenic magnetometer. In addition, the major focus of this paleomagnetic study is to examine the relationship between the timing of remanence acquisition with respect to the primary (F1) and the secondary (F2) folds of the Paradox anticline. To this extent, oriented samples of carbonates have been collected from the Ordovician Cool Creek Formation of the Paradox anticline from the Slick Hills area from both the F1 and the F2 folds. Low temperature demagnetization protocols have been carried out on these samples to remove the effects of multidomain magnetite grains thereby isolating better the characteristic remanence components. Post-low temperature cleaning, the thermal step-demagnetization procedure isolates primarily two components: 1.) a low-temperature steep downward viscous remanent magnetization; and, 2.) a high-temperature characteristic remanent magnetization component, residing primarily in magnetite, with shallow remanence directions scattered towards the east-south-east to south-east. Fold test results indicate a post-tilting remanence for the F1 major folding of the Paradox anticline similar to that observed by Elmore et al. (1988). However, an interesting new observation is the paleomagnetic fold test results from the F2 fold that indicates a syntilting remanent magnetization. In addition, the south-easterly scattered shallow remanence directions from these Ordovician Cool Creek carbonates substantiates a possible 30° rotation that is likely attributed to the left-lateral wrench faulting observed in this area.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 1525 Paleomagnetism applied to tectonics: regional;
- 1533 Remagnetization;
- 8005 Folds and folding;
- 8045 Role of fluids