Magnetization process of serpentine

蛇纹石的磁化过程

• 批准号: 23654173
• 负责人: OTOFUJI Yo-ichiro
• 金额: $ 2.33万
• 依托单位: Kobe University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Challenging Exploratory Research
• 财政年份: 2011
• 资助国家: 日本
• 起止时间: 2011 至 2013
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-23654173/
• 关键词: 蛇紋岩; 古地磁気学; 岩石磁気学; 西南日本弧; 東北日本弧; 残留磁化; テクトニクス; 蛇紋岩化作用; 古地磁気

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.

在日本西南部的四个地区（大平山、久津龙河、白马、大屋白津）和日本东北部的日立大田采集了蛇尾草。蛇纹石的剩磁由磁铁矿携带。 蛇纹岩的剩余磁化强度可能是由长周期岩的热液蚀变过程中产生的磁铁矿获得的，樱江、大江山和九津龙川的蛇纹岩的剩余磁化强度显示出向北偏东的方向（D=60-90 °; I=50 °），与日本西南部年龄大于15 Ma的火成岩的剩余磁化强度平行。在日本西南部经历顺时针旋转之前，这些地区的Serranean获得了Reversal磁化。其他地区的地磁场显示出不同的地磁场方向，如现今地磁场方向和反向。 蛇纹岩化作用在15 Ma以前和15 Ma至今的不同时期多次发生。