Relative paleointensity of the geomagnetic field over the last 200,000 years from ODP sites 883 and 884, North Pacific Ocean

Author(s): Roberts, Andrew P.; Lehman, Benoît; Weeks, Robin J.; Verosub, Kenneth L.; Laj, Carlo
Author Affiliation(s): Primary:
University of Southampton, Department of Oceanography, Southampton, United Kingdom
CNRS-CEA, France
University of Washington, United States
University of California at Davis, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 152(1-4), p.11-23. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Cent. Faibles Radioact., Contrib. No. 1979. 37 refs.; illus., incl. 1 table, sketch map
Summary: Ocean Drilling Program Sites 883 and 884 were cored as part of a three-site depth transect down the slopes of Detroit Seamount in the North Pacific Ocean. Continuous mineral magnetic and paleomagnetic measurements were made using u-channel samples for sediments that span the last 200 kyr. Thermomagnetic and high-field hysteresis data indicate that the magnetic mineralogy of the clay-rich sediments at the two sites is dominated by pseudo-single domain magnetite in a narrow range of grain sizes and concentrations, thereby meeting established criteria for relative paleointensity studies. The natural remanent magnetization (NRM) has been normalized using the anhysteretic remanent magnetization (ARM) and the low field magnetic susceptibility (χ). The NRM/ARM and NRM/χ records are nearly identical for both cores. Furthermore, coeval horizons in the two cores can be correlated by matching >100 magnetic susceptibility features over the 15 m length of both cores. Coherence function analysis indicates that the records are not significantly affected by local environmental conditions. These factors suggest that the large-scale variations in normalized remanence are most likely due to geomagnetic paleointensity fluctuations. Dating constraints are provided by a δ18O stratigraphy from Site 883. Our North Pacific paleointensity versus age curve is similar to a published record from the western Caroline basin and a recently proposed global paleointensity curve. Offsets (up to 10 kyr) in the timing of paleointensity features between our composite North Pacific record and the global curve may result from imprecisions in the dating of our record. Nevertheless, the correspondence between the paleointensity records suggests that, in suitable sediments, paleointensity of the geomagnetic field can give a globally coherent, dominantly dipolar, signal. Abstract Copyright (1997) Elsevier, B.V.
Year of Publication: 1997
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 24 Surficial Geology, Quaternary Geology; Anhysteretic remanent magnetization; Cenozoic; Chemostratigraphy; Cores; Detroit Seamount; Isotope ratios; Isotopes; Leg 145; Magnetic field; Magnetic hysteresis; Magnetic intensity; Magnetic properties; Magnetic susceptibility; Magnetization; Marine sediments; Natural remanent magnetization; North Pacific; O-18/O-16; ODP Site 883; ODP Site 884; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleomagnetism; Quaternary; Remanent magnetization; Seamounts; Sediments; Stable isotopes; Upper Quaternary
Coordinates: N511155 N511155 E1674607 E1674607
N512702 N512702 E1682013 E1682013
Record ID: 1998013414
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands