HR: 0830h
AN: GP11C-0268    [PDF]
TI: Sediment Magnetism and Paleo-depositional Environment of Deep-sea Sediments From KODOS Area in the Northeastern Equatorial Pacific
AU: * Park, C
EM: ckpark@kordi.re.kr
AF: Korea Ocean Research & Development Institute, Ansan P.O.Box 29, Ansan, 425-600 Korea, Republic of
AU: Son, S
EM: skson@kordi.re.kr
AF: Korea Ocean Research & Development Institute, Ansan P.O.Box 29, Ansan, 425-600 Korea, Republic of
AU: Kim, K
EM: kkim@kordi.re.kr
AF: Korea Ocean Research & Development Institute, Ansan P.O.Box 29, Ansan, 425-600 Korea, Republic of
AU: Doh, S
AF: Korea University, Korea Unuvirsity, Seongbuk-ku, Seoul, 136-701 Korea, Republic of
AB: Paleomagnetic properties of sediment cores of the KODOS (Korea Deep Ocean Study) area located in the northeastern equatorial Pacific were studied to understand paleo-depositional condition. In the northeastern equatorial Pacific, magnetic properties of sediment samples for this study were recorded by stable NRM carriers, and the paleomagnetic directions were well-grouped in each polarity interval. The values of inclination in the surface sediments were similar to the expected inclination values for the period from present to Pleistocene at the sampling sites. The polarity sequence of the studied sediments can be correlated with the geomagnetic polarity time scale for the period of early Pliocene and Pleistocene time. The paleomagnetic stratigraphy shows that the sedimentation rates were 1.04 mm/kyr for Pleistocene and 0.75 mm/kyr for Late Pliocene. The average sedimentation rate of Pleistocene is about 1.53 times higher than that of late Pliocene. The variations of sedimentation rates with age can be explained by the paleoceanographic event. For Pliocene and Pleistocene age, the depositional environment in the Pacific is characterized by the onset of northern hemisphere glaciation and subsequent climatic deterioration. During these periods, large amount of eolian materials were transported to the deep-sea floor. An increasing sedimentation rates for Pleistocene imply that the terrestrial materials were primarily transported to the ocean and the biogenic sedimentation was also increased as a result of increased primary productivity. The down-core variations of paleomagnetic and rock-magnetic properties of the KODOS core sediments were affected by the dissolution processes in an oxic depositional regime. The high NRM stability in the upper yellowish brown layers implied that the magnetic carrier was initially in SD and PSD states. In the lower dark brown sediments, only fine magnetic carrier was survived from the dissolution and NRM was carried by more abundant MD grains, which had the low magnetic stability. When sufficient high-stability detrital magnetic grains exist, paleomagnetic directional components carried by such grains can survive despite active diagenetic process.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1518 Magnetic fabrics and anisotropy
DE: 1519 Magnetic mineralogy and petrology
DE: 1520 Magnetostratigraphy
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting