Rock-Magnetic Records of 0 - 2.5 Ma Deep-Sea Core Sediments in Pacific Region

In conjunction with magnetostratigraphic results, a rock-magnetic investigation is carried out to clarify paleo-environmental changes in sedimentary sequences of piston core recovered from abyssal basin of Pacific. Study area is surrounded by Marshall islands to the east and Mariana islands to the west. Sampling site is located in abyssal basin between OSM 01 (Ita Mai Tai seamount) and OSM 02 (unnamed seamount). Magnetic susceptibility, anhysteretic remanent magnetization (ARM), and saturation isothermal remanent magnetization (SIRM) were measured on core sample. In previous results, the age of sediments was from late Pliocene and Pleistocene determined by matching the polarities with the geomagnetic time scale. Sedimentation rates were ranged from 63 to 85 cm/Ma. Rock-magnetic experiments indicate that remanence is carried by ferrimagnetic minerals having low coercivity. With core depth, The fluctuations of rock-magnetic parameters in depth of lithologic change appear to be caused by the input change of magnetic minerals reflecting the variation of paleo-depositional condition.