Relative paleointensity (RPI) and oxygen isotope stratigraphy at IODP Site U1308; North Atlantic RPI stack for 1.2-2.2 Ma (NARPI-2200) and age of the Olduvai Subchron

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doi: 10.1016/j.quascirev.2015.10.011
Author(s): Channell, J. E. T.; Hodell, D. A.; Curtis, Jason H.
Author Affiliation(s): Primary:
University of Florida, Department of Geological Sciences, Gainesville, FL, United States
Other:
University of Cambridge, United Kingdom
Volume Title: Quaternary Science Reviews
Source: Quaternary Science Reviews, 131( Part A), p.1-19. Publisher: Elsevier, International. ISSN: 0277-3791
Note: In English. 74 refs.; illus., incl. 3 tables, sketch map
Summary: Integrated Ocean Drilling Program (IODP) Site U1308 (49°53'N, 24°14'W; water depth 3871 m) provides a record of relative paleointensity (RPI) and benthic stable isotope stratigraphy back to 3.2 Ma. The record since 1.5 Ma was published previously, and here we present the interval from 1.5 Ma to 3.2 Ma (Early Pleistocene-Late Pliocene). The benthic oxygen isotope record in this interval is correlated to Marine Isotope Stage (MIS) 51 to KM2, with an apparent hiatus that removed part of the interval spanning MIS 104-G2 (2.6-2.65 Ma), at 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 benthic oxygen isotope record to a global stack (LR04). Apart from the expected polarity reversals, three magnetic excursions are recorded: Punaruu in MIS 31/32 at 1092 ka, Gilsa in MIS 54/55 at 1584 ka, and a newly recognized excursion labeled Porcupine (after the nearby Porcupine Abyssal Plain) in MIS G6/G7 at 2737 ka. The ages of polarity reversals at Site 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 that occurred in MIS 73, corresponding to 1925 ka on the LR04 time scale, 25 kyr younger than in the current GPTS. The RPI record at Site 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) that is compared with published RPI stacks: Epapis, Sint-2000 and PADM2M. For 2.2-3.2 Ma, the Site U1308 RPI record is compared with a RPI record from North Atlantic IODP Site U1314, and with the Pacific Epapis stack. The mean sedimentationrates 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 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 U1308 yields a very similar mean value for the Brunhes and Matuyama virtual axial dipole moments (7.05 × 1022 Am2), implying no polarity bias in the strength of the main geomagnetic dipole, in contrast to interpretations from Sint-2000 and PADM2M. The results strengthen the case that RPI can be used to improve global stratigraphic correlation for sites with mean sedimentation rates up to several decimeters/kyr. Abstract Copyright (2016) Elsevier, B.V.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Cenozoic; Chemostratigraphy; Chronostratigraphy; Cores; Expedition 303; Expeditions 303/306; IODP Site U1308; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Lower Pleistocene; Magnetic intensity; Magnetization; Magnetostratigraphy; Marine sediments; Mid-Atlantic Ridge; Natural remanent magnetization; Neogene; North Atlantic; Northeast Atlantic; O-18/O-16; Olduvai Subchron; Oxygen; Paleomagnetism; Pleistocene; Pliocene; Quaternary; Relative age; Remanent magnetization; Reversals; Sediments; Stable isotopes; Tertiary; Upper Pliocene
Coordinates: N495300 N495300 W0241400 W0241400
Record ID: 2016091692
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands