Magnetization process of serpentine

点击翻译按钮获取中文摘要

Serpentine is collected at four areas in Southwest Japan (Oheyama,Kuzuryu-river, Hakuba, Oyashirazu) and at Hitachi Ohta in Northeast Japan. Remanent magnetization of serpentine is carried by magnetite. Remanent magnetization of serpentine is probably acquired by magnetite which occurrs during hydro-thermal alteration of periodite.Remanent magnetizations of serpentine at Sakurae, Oheyama and Kuzuryu-river show easterly deflected directions from the north (D=60-90 degree; I=50 degree) which is parallel to the remanent magnetization of igneous rocks in Southwest Japan with ages older than 15Ma. Serpentine at these areas acquired the remanent magnetization before Southwest Japan experienced clockwise rotation. Serpentine from other areas reveal variable directions in the remanent magnetizaiton; such as, present geomagnetic field direction and reversed directions. We conclude that serpentinization occurrs at many times in various periods prior to 15 Ma and between 15Ma and present.