Publication Date:
2017-04-04
Description:
We conducted detailed rock magnetic investigations on 36m of drill core collected during Ocean Drilling Program Leg 195 at
Hole 1202B (24◦48.24 N, 122◦30.00 E), in the Southern Okinawa Trough, with the goal of extracting a reliable paleointensity signal
with centennial resolution. An age-depth model was established from a chronology obtained by accelerator mass spectromety 14C
dating. The sedimentary section spans almost the entire Holocene (0–9.4 kyr) and exhibits sedimentation rates close to 400 cm/kyr.
The magnetic properties are dominated by stable, pseudo-single domain magnetite. High-field hysteresis data and the grain-size
sensitive ratio of anhysteretic remanent magnetization (ARM) to low field magnetic susceptibility indicate a narrow range of grain
sizes and concentrations. Magnetic parameters vary by a factor of 4 thereby fulfilling the usual criteria for a relative paleointensity
study. The relative geomagnetic paleointensity was obtained by normalizing the intensity of natural remanent magnetization (NRM)
by the ARM and the low field magnetic susceptibility. Both normalizations yield nearly identical results (r = 0.89). Spectral analysis
indicates that the record is not significantly affected by local environmental conditions. Comparison of thisWest Pacific paleointensity
curve with other curves suggests a geomagnetic origin for the signal. Millennial-scale features of our record correlate to variations
of the archeomagnetic dipole moment. This suggest that the sediments at Hole1202B recorded changes of the geomagnetic field
over the studied time interval.
Description:
Published
Description:
179–193
Description:
open
Keywords:
Paleomagnetism
;
Paleointensity;
;
Paleosecular variation;
;
Holocene;
;
04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
1162269 bytes
Format:
application/pdf
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