Paleomagnetic investigation of the igneous sequence, Site 807, Ontong Java Plateau, and a discussion of Pacific true polar wander

Abstract

Characteristic remanent magnetizations derived from detailed thermal and alternating-field demagnetization of basalts recovered at Ocean Drilling Program (ODP) Site 807 reveal constant normal polarity consistent with paleontological ages from overlying sediments, suggesting deposition in early Aptian times at the beginning of the Cretaceous Normal Polarity Superchron (K-N). Hotspot-based plate reconstructions for the Early Cretaceous place the Ontong Java Plateau on the Louisville hotspot, presently located at 51°S, whereas the paleolatitude for Site 807 based on the Pacific APWP is 34°S. Because the nominal mean inclination from Site 807 and values derived from Deep Sea Drilling Project (DSDP) sediments of other sites predict shallower palaolatitudes for the Ontong Java Plateau, values from the Pacific APWP provide lower bounds on true polar wander. The Louisville hotspot appears to have moved 9°-17° to the south relative to the spin axis since the Early Cretaceous. -from Authors