Hydrothermal alteration processes of Mg-clay minerals (saponite and kerolite) at the Wakamiko submarine crater, Kagoshima bay, Japan

Abstract

We studied hydrothermal alteration clay minerals collected from the Wakamiko submarine crater located at 200 water meters depth in the Kagoshima Bay. Mineral and chemical composition of the clay minerals was determined using XRD, TEM. For some specific alteration clay minerals, oxygen isotopic composition was measured to estimate formation temperature. Mg-clay minerals such as saponite and kerolite were attributed to be formed from felsic volcanic material by Mg uptake from the seawater under the condition of high temperature.