A composite record of Late Pleistocene relative geomagnetic paleointensity from Wilkes Land Basin (Antarctica)

• Published in: Physics of the Earth and Planetary Interiors
• Main Authors: Macrì, P., Sagnotti, L., Dinarès-Turell, J., Caburlotto, A.
• Other Authors: Macrì, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Caburlotto, A.; INOGS - Borgo Grotta Gigante 42/c, Sgonico (TS), Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, INOGS - Borgo Grotta Gigante 42/c, Sgonico (TS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2005
• Subjects: Paleomagnetism; Relative paleointensity; Geomagnetic excursions; Antarctica; Brunhes Chron; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field; East Antarctica; Wilkes Land; Wega; Antarc*
• Online Access: http://hdl.handle.net/2122/3572; https://doi.org/10.1016/j.pepi.2005.03.004

We report high-resolution paleomagnetic records obtained from six piston cores recovered on the continental rise of theWilkes Land Basin (WLB), East Antarctica, in the frame of the Italian/Australian Wilkes Land Glacial History (WEGA) project. The studied cores, with a length of ca. 4m each, were collected from the gentle and steep sides of sedimentary ridges present in the lower part of the continental rise, and consist of very fine-grained sediments. Paleomagnetic measurements were carried out on u-channel samples. Apart from a low-coercivity magnetic overprint, removed after the first steps of alternating field demagnetization, each core is characterized by a well defined characteristic remanent magnetization. Paleomagnetic inclinations fluctuate around the expected value (of ca. −77◦) for such high latitude sites and always indicate normal magnetic polarity. Short period oscillations to anomalously shallow paleomagnetic inclinations (up to −20◦) were identified at different levels of the sampled sequences; positive (reverse) inclination values were however not observed. Specific rock magnetic measurements indicate a substantial homogeneity of the magnetic mineralogy in the sampled sequences. For each core we reconstructed curves of relative paleointensity (RPI, as computed by NRM20mT/κ and NRM20mT/ARM20mT) variation of the geomagnetic field. An original age modelwas established by tuning the individual RPI curves with the available global and regional reference RPI stacks. Paleomagnetic results, supported by other limited bio- and chronostratigraphic constraints, establish that all the cores are Late Pleistocene in age: two provide an expanded record of the last ca. 30 ka (PC18 and PC19), three span the last ca. 100, 200 and 300 ka (respectively, PC25, PC27 and PC26), and one reaches back to ca. 780 ka (PC20), approaching the Brunhes–Matuyama transition. Thus, the WEGA paleomagnetic record provides the first experimental data documenting the dynamics and amplitude of the geomagnetic field variations at high ...