A comparative analysis of magnetic properties in rocks: Five active submarine volcanoes in the western Pacific

We studied the petrophysical and magnetic properties of dredged rocks that compose the edifices of five active submarine volcanoes in the Pacific Ocean, viz., the Fukujin, Esmeralda, Kovachi, and Simbo at island arcs, and Ile des Cendres in a marginal sea. We measured the standard petrophysical and magnetic characteristics and performed three kinds of thermomagnetic analysis as well as an electron-probe analysis. Comparative analysis of magnetic properties in rocks showed that they are strongly differentiated by the value of natural remanent magnetization and of magnetic susceptibility. The greatest values are shown by the Esmeralda aphyric basaltic andesites, the lowest occur in the Ile des Cendres xenoliths. The principal carriers of magnetization in the rocks are grains of unaltered and/or oxidized titanomagnetite with varying domain structures. All the samples are magnetically isotropic.