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doi:10.2204/iodp.proc.303306.215.2011 ResultsMost magnetic susceptibilities of the sand layers are ~2.0 × 10–6 to 4.0 × 10–6 m3/kg, and those of detrital carbonate layers are relatively low at 1.0 × 10–7 to 3.0 × 10–7 m3/kg (Table T1). This result corresponds to the onboard measurement results as shown in the “Site U1305” chapter (Expedition 303 Scientists, 2006b). AMS parameters (L, F, P, P′, T, and q) are shown in Table T1. The magnetic minerals that contribute to the magnetic susceptibility and their anisotropy are assumed to be ferrimagnetic minerals according to their Khf/Klf ratio. This reflects the contribution percentage of paramagnetic minerals at low magnetic field, which is <15% (Table T2), suggesting that the contribution is >85% for ferrimagneric minerals. We note a significant difference in Khf/Klf ratios between detrital carbonate and sand layers samples. Three stereographic projections (Fig. F4) show the orientations of Kmax, Kint, and Kmin, with rose diagrams of Kmax declination. Kmax directions are largely scattered, but the majority of Kmax values in sand layers resides in the northeast of the diagram (with 5°–10° inclination) with subordinate south-plunging ones. Kmin values are mostly concentrated in a vertical direction with 5°–10° northwest plunge. Kmax directions in the detrital carbonate layers dominantly plunge to the south. On the basis of previous studies associated with paleocurrent analyses using the AMS (e.g., Taira, 1989), Kmax direction in this result may correspond to the paleocurrent direction, indicating that the directions in the sand layers and detrital carbonate layers are from south to north. |
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