Paleomagnetic and rock magnetic studies of the sediment samples from Site 797 were carried out. Thermal demagnetization was found to be more effective in removing secondary overprinting than alternating field demagnetization. Production of new magnetic minerals during the thermal treatment was frequently observed and made thorough demagnetization difficult, however. Thermal demagnetization of orthogonal IRM's suggests that magnetite and pyrrhotite are common magnetic minerals in these sediments. The Lowrie-Fuller test and xARM/x ratio show apparent grain size of the magnetic minerals to be that of single-domain to small multi-domain state. A downcore decrease of rock magnetic parameters such as ARM, IRM, and xARM/x ratio in the upper half of the hole indicates progressive diagenetic dissolution of finer magnetic minerals. In the lower part where igneous rocks intruded, production of magnetic minerals is suggested by discontinuous change of the downcore trend, which may have brought remagnetization of the sediment samples.

Supplement to: Torii, Masayuki; Hayashida, Akira; Vigliotti, Luigi; Wippern, Jobst J M (1992): Rock magnetic properties of sediments from Site 797, Japan Sea. In: Tamaki, K; Suychiro, K; Allan, J; McWilliams, M; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 127/128(2), 947-957