Global and regional geomagnetic variabilities recorded in late Quaternary sediments from the west Iberian Margin

High-resolution palaeomagnetic records preserved in sediments (especially those that are well dated) provide valuable continuous information on past changes in Earth’s magnetic field. These data are essential for us to develop better understanding on the dynamics and causes of geomagnetic changes at various time scales. In this study, we conducted palaeomagnetic analyses on continuous u-channel samples collected from well-dated late Quaternary sediment sequences cored in the west Iberian Margin during Integrated Ocean Drilling Program (IODP) Expedition 339. Natural remanent magnetisations (NRM) as well as a suite of laboratory-induced magnetisations of the samples were measured at 1-cm interval resolution on a superconducting rock magnetometer before and after stepwise alternating field (AF) demagnetisation. NRM demagnetization data of the samples reveal a very stable and well-defined primary magnetisation component. Chronology of the studied cores is well constrained and tied to the polar ice cores as well as the absolutely dated Asian speleothem records. Average sedimentation rates of the studied cores range between ~10 cm/kyr to over 70 cm/kyr. Relative palaeointensity (RPI) records reconstructed from these sediments, when placed on the acquired age models, correlate well with other global and regional RPI records on time scales of ~10 kyr or longer. RPI features recorded at higher sedimentation rate sites appear slightly younger (a few hundreds to a couple of thousand years), possibly due to effects of the sediment magnetisation lock-in process. These Iberian Margin RPI records also show common millennial to multi-millennial scale variabilities, especially after deconvolution and correction of the lock-in induced age offset.