HR: 0800h
AN: GP11D-0857    [Abstracts]
TI: Low latitude geomagnetic field variation at the Banda Sea during the past 800 kyr
AU: * Huang, Y
EM: yinson@oc.gep.ncu.edu.tw
AF: Institute of Geophysics, National Central University, No.300, Jhongda Rd., Jhongli, Taoyuan, Taiwan., Jhongli, 320 Taiwan
AU: Lee, T
EM: tqlee@earth.sinica.edu.tw
AF: Intitute of Earth Sciences, Academia Sinica, No.128 sec. 2, Academia Rd., Nankang, Taipei, Taiwan., Taipei, 115 Taiwan
AU: Hsu, S
EM: hsu@oc.gep.ncu.edu.tw
AF: Institute of Geophysics, National Central University, No.300, Jhongda Rd., Jhongli, Taoyuan, Taiwan., Jhongli, 320 Taiwan
AB: We reconstruct the geomagnetic field reversals at the Banda Sea by using paleomagnetic data from the core MD012380 during the International Marine Global Change Study (IMAGES) VII Cruise in 2001. Magnetic analysis is carried out for the whole core on the basis of discrete measuring with a spacing of 1 cm. Magnetic susceptibility ($\chi$), nature remanent magnetization (NRM), anhysteretic remanent magnetization (ARM), and isothermal remanent magnetization (IRM) are measured. Our results reveal the low latitude geomagnetic field variation at the Band Sea during the last 800 kyr. Except for the Brunhes/Matuyama boundary, there is no clear reverse signal in the paleo-direction (paleo-inclination and paleo-declination) pattern. This causes the difficulty in identifying reverse subchrons. However, the synthetic paleointensity curve displays asymmetrical saw-tooth pattern, available for indicating polarity reversals, and shows a maximum intensity drop at the Brunhes/Matuyama boundary. The characteristic of paleointensity provides a useful tool to determine the reverse events and modifies the problems arose from using the paleo-direction pattern, especially at low latitude. With the help of the paleo-direction pattern, we have identified seven reverse events, two excursions and three possible polarity subchrons during the Brunhes chron.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1512 Environmental magnetism
DE: 1522 Paleomagnetic secular variation
DE: 1535 Reversals (process, timescale, magnetostratigraphy)
DE: 1560 Time variations--secular and long term
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting