Magnetization directions (Declination, Inclination, MAD), relative paleointensity (RPI) and susceptibility for IODP Site 303-U1308 for 100-248 mcd (1.3-3.2 Ma)

Integrated Ocean Drilling Program (IODP) Site 303-U1308 (49° 53'N, 24° 14'W; water depth 3871 m) provides a record of magnetization directions, relative paleointensity (RPI), susceptibility and benthic stable isotope stratigraphy back to 3.2 Ma. The record since 1.5 Ma has been published (Channell et al., Earth and Planetary Science Letters, 274, 59-71, 2008). This paper deals with the interval from 1.3 Ma to 3.2 Ma (Early Pleistocene-Late Pliocene). The benthic oxygen isotope record in this interval can be correlated to marine isotope stages (MIS) 51 to KM2, with an apparent hiatus that removed MIS G1-G2, immediately below the Gauss-Matuyama boundary. The mean sedimentation rate for the 1.5-3.2 Ma period is 8.5 cm/kyr. The age model was built by correlation of the oxygen isotope record to the LR04 stack. Carbon isotope data imply the influence of North Atlantic Deep Water (NADW) during interglacials with influence of southern source waters during glacials throughout the period, but with more muted δ¹³C variations in the Gauss Chron. Apart from the expected polarity reversals, three magnetic excursions are recorded: Punaruu in MIS 31/32 at 1092 ka, Gilsa in MIS 54 at 1584 ka, and a newly recognized excursion labeled Porcupine (after the nearby Porcupine abyssal plane) in MIS G7 at 2737 ka. The ages of reversals at Site 303-U1308, on the LR04 time scale, are consistent with the current geomagnetic polarity timescale (GPTS) with the exception of the base of the Olduvai Subchron in MIS 73 at 1925 ka, 26 kyr younger than in the current GPTS. The RPI record at Site 303-U1308 is calibrated using the oxygen isotope age model, and combined with four other North Atlantic records to obtain a North Atlantic RPI stack for 1.2-2.2 Ma (NARPI-2200). For 2.2-3.2 Ma, no Atlantic RPI records other than Site 303-U1308 exist. The NARPI-2200 stack is compared with published RPI stacks: Epapis, Sint-2000 and PADM2M. The mean sedimentation rates of the North Atlantic sites in NARPI-2200 are greater (by about an order of magnitude) than most of the records incorporated in other stacks. The comparison of Pacific Epapis and NARPI-2200 yields an apparent lag for NARPI-2200 relative to Epapis, attributed the Epapis age model constructed by correlation of magnetic concentration parameters (a proxy for carbonate percentage) to a calibrated oxygen isotope record. The long RPI record from Site 303-U1308 yields a very similar mean value for the Brunhes and Matuyama virtual axial dipole moments (7.5 x 1022 A m²), implying no polarity bias for RPI as in Sint-2000 and PADM2M. The results strengthen the case that RPI can be used to improve global stratigraphic correlation, especially for sites with mean sedimentation rates up to several decimeters/kyr.