HR: 1340h
AN: GP43B-1216    [Abstracts]
TI: Rock magnetic and geochemical analyses of surface sediment characteristics in deep ocean environments: A case study across the Ryukyu Trench
AU: * Kawamura, N
EM: kawamura-noriko@aist.go.jp
AF: Noriko Kawamura, Geological Survey of Japan, AIST, 1-1-1 Higashi, Central 7, Tsukuba , JAPAN, Tsukuba, 305-8567, Japan
AU: Kawamura, K
EM: kichiro@fgi.or.jp
AF: Noriko Kawamura, Geological Survey of Japan, AIST, 1-1-1 Higashi, Central 7, Tsukuba , JAPAN, Tsukuba, 305-8567, Japan
AU: Ishikawa, N
EM: ishikawa@gaia.h.kyoto-u.ac.jp
AF: Noriko Kawamura, Geological Survey of Japan, AIST, 1-1-1 Higashi, Central 7, Tsukuba , JAPAN, Tsukuba, 305-8567, Japan
AB: Magnetic properties in marine sediments are one of the most powerful tools for marine sedimentological studies. Magnetic minerals, which are magnetic carriers of natural remanent magnetization and paleoclimate signals marine sediments are commonly dissolved and formed with burial depth, and mask the primary magnetic properties. In order to clarify the progressive changes in the magnetic properties, we studies seven cores collected from the Ryukyu Trench, southwest Japan. Magnetic properties, organic geochemistry, and interstitial water chemistry of seven cores are described. The magnetic carriers in the sediments are predominantly magnetite and maghemized magnetite with minor amount of hematite. Results of the topmost sediments from the landward slope showed that magnetic minerals were diluted by terrigenous materials and microfossils. The downcore variations in magnetic properties and geochemical data from three cores provided evidence for the dissolution of fine-grained magnetite with burial, and that the fine-grained magnetite is well preserved in oxic condition.
UR: http://staff.aist.go.jp/kawamura- noriko/�@
DE: 1051 Sedimentary geochemistry
DE: 1512 Environmental magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting