High-resolution relative paleointensities over the last 40 ka from marine sediments in the western equatorial pacific: Magnetic events and interhemispheric correlation

Abstract

Core MD01-2385 retrieved in the western equatorial Pacific (Northwest of Papua-New Guinea) has been sampled every 2 cm for paleomagnetic and radiocarbon measurements. The age model, well constrained by 47 14C ages (both new and former), indicates that our record spans approximately the last 38 ka. The average sedimentation rate is ∼30 cm/ka. Analysis of the magnetic mineralogy revealed that the natural remanent magnetization (NRM) is predominantly carried by magnetite. A relative paleointensity record (RPI) was derived, allowing us to estimate a lock-in depth of approximately 18 cm, corresponding to ∼600 years in our case, by comparing it with the CALS10k.2 model. Comparison with two other western Equatorial Pacific RPI, selected for their geographical proximity (∼1000 km) and high resolution, allowed us to compile a regional reference record (WEPEQ). Several intervals of lower intensities have been identified and may correspond to the known events of Mono Lake (∼34 ka), Rockall (∼27 ka), Hilina Pali (∼18 ka) and possibly Tianchi (∼5–8 ka). Overall, our equatorial curve exhibits strong similarities with RPI curves from mid to low latitudes, such as those from the Iberian Margin and Black Sea. A detailed investigation hints at the presence of non-dipolar structures in the Earth's magnetic field at the shorter time scale, especially during the low intensity intervals. In contrast, notable differences are observed when compared to high-latitude stacks, especially from the North Atlantic (NAPIS). This points to the potential climatic bias that may affect high-latitude records during the glacial maximum and glacial-interglacial transition.