JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Poster

S (Solid Earth Sciences) » S-EM Earth's Electromagnetism

[S-EM18] [EE] General Contributions in Geomagnetism, Paleomagnetism, and Rockmagnetism

Sun. May 21, 2017 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall HALL7)

convener:Hirokuni Oda(Institute of Geology and Geoinformation, Geological Survey of Japan, AIST), Nobutatsu Mochizuki(Priority Organization for Innovation and Excellence, Kumamoto University), Joshua M Feinberg(University of Minnesota), Myriam Annie Claire Kars(Center for Advanced Marine Core Research)

[SEM18-P13] Composition law of oblique anhysteretic remanent magnetization and its relation to the magnetostatic interaction

*Masahiko Sato1, Nobutatsu Mochizuki2, Minako Watanabe3, Hideo Tsunakawa4 (1.National Institute of Advanced Industrial Science and Technology, 2.Kumamoto University, 3.National Institute of Technology, Nagaoka College, 4.Tokyo Institute of Technology)

Keywords:Anhysteretic Remanent Magnetization, Magnetostatic Interaction, Rock Magnetism

The basic properties of oblique anhysteretic remanent magnetization (OARM) acquired in a weak and steady magnetic field with an arbitrary angle to the alternating field direction were studied. OARM and rock-magnetic experiments were conducted on samples of basalt, granite, and sediment containing non-interacting single-domain (SD), interacting SD, pseudo-single-domain, and multidomain low-Ti titanomagnetites. The intensity of OARM (MOARM) systematically increased or decreased with increasing angle between alternating and steady field directions (θSF), while the angle between alternating field and OARM directions (θOARM) increased with increasing θSF for all samples. During stepwise alternating field demagnetization, the OARM vector shows a single component parallel to the steady field direction for θSF = 0° (ARM||) and 90° (ARM). The median destructive field of ARM is larger than that of ARM||. For intermediate angles (θSF = 30°, 45°, and 60°), the OARM vector was not parallel to the applied steady field; instead, it gradually increased with coercivity. These experiments indicate that the OARM vector is approximately given by the sum of two orthogonal magnetizations coinciding with ARM|| and ARM, respectively. Thus, the OARM vector can be determined by acquisition efficiencies of ARM|| and ARM in an individual sample. Based on these experiments and associated rock-magnetic measurements, non-interacting SD samples show lower ARM/ARM|| ratios, compared to other samples. This result suggests that OARM can be used as a conventional tool to detect non-interacting SD particles in the paleomagnetic samples.