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doi:10.2204/iodp.proc.314315316.222.2015

Data report: anisotropy of magnetic susceptibility measurement on samples from Sites C0004, C0006, C0007, and C0008, IODP Expedition 316¹

Yujin Kitamura,² Xixi Zhao,^{3, 4} and Toshiya Kanamatsu⁵

Abstract

We carried out anisotropy of magnetic susceptibility (AMS) measurements on samples from Integrated Ocean Drilling Program Sites C0004, C0006, C0007, and C0008 recovered during Expedition 316 to examine their magnetic fabrics. Magnetic susceptibility, Km, varied with lithology at each drilling site. Nondeformed sediments should show a positive shape parameter, T, indicating retention of their initial state of deposition and compaction. At Site C0004, the shape parameter reveals a scattered plot in the units of the megasplay fault zone and mass wasting deposits. A similar trend was observed in Unit I at Site C0007 in the prism toe, which also consists of mass wasting deposits. In contrast, the mass transport complex at Site C0008 has an enhanced compaction fabric. Despite the existence of many thrusts, the sediments at Sites C0006 and C0007 display a trend associated with compaction, with a drastic change in the orientation of magnetic fabric at the bottom of the holes. As a general implication, the sediments in this area obtained rather flattened fabrics at first and kept them, unless they were affected by later mechanical deformation. Due to tectonic disturbances in mass wasting deposits and the megasplay fault, deformed sediments/rocks are characterized by dispersed shape parameter values. Our results suggest that the AMS is potent to characterize mechanically disordered units in core samples and provides useful information for the onset of seismogenic behavior and locking of subduction thrusts.

¹ Kitamura, Y., Zhao, X., and Kanamatsu, T., 2015. Data report: anisotropy of magnetic susceptibility measurement on samples from Sites C0004, C0006, C0007, and C0008, IODP Expedition 316. In Kinoshita, M., Tobin, H., Ashi, J., Kimura, G., Lallemant, S., Screaton, E.J., Curewitz, D., Masago, H., Moe, K.T., and the Expedition 314/315/316 Scientists, Proc. IODP, 314/315/316: Washington, DC (Integrated Ocean Drilling Program Management International, Inc.).
doi:10.2204/iodp.proc. 314315316.222.2015

² Department of Earth and Environmental Sciences, Graduate School of Science and Technology, Kagoshima University, 1-21-35 Korimoro, Kagoshima 890-0065, Japan. yujin@sci.kagoshima-u.ac.jp

³ State Key Laboratory of Marine Geology, Tongji University, 1239 Siping Road, Shanghai 200092, China.

⁴ Department of Earth and Planetary Sciences, University of California Santa Cruz, 1156 High Street, Santa Cruz CA 95064, USA.

⁵ R&D Center for Earthquake and Tsunami, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka-city, Kanagawa 237-0061, Japan.

Initial receipt: 27 June 2013
Acceptance: 19 April 2015
Publication: 6 July 2015
MS 314315316-222

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