JpGU-AGU Joint Meeting 2017

講演情報

[EE] ポスター発表

セッション記号 S (固体地球科学) » S-EM 固体地球電磁気学

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

2017年5月21日(日) 13:45 〜 15:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:小田 啓邦(産業技術総合研究所地質情報研究部門)、望月 伸竜(熊本大学大学院先導機構)、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

*佐藤 雅彦1望月 伸竜2渡邉 美奈子3綱川 秀夫4 (1.産業技術総合研究所、2.熊本大学、3.長岡工業高等専門学校、4.東京工業大学)

キーワード: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.