Pre-historic secular variation of the geomagnetic field and its application to the archeomagnetic dating
Grant-in-Aid for General Scientific Research (A)
|Allocation Type||Single-year Grants |
|Research Institution||Toyama University |
HIROOKA Kimio Faculty of Science, Toyama University, Professor, 理学部, 教授 (30029467)
WADA Seigo Faculty of Literatures, Ritumeikan Univ.,Assistant Professor, 文学部, 助教授 (30115969)
NAKAJIMA Tadashi Faculty of Education, Fukui Univ.,Assistant Professor, 教育学部, 助教授 (70093440)
UNO Takao Faculty of Humanities, Toyama Univ., Assistant Professor, 人文学部, 助教授 (70115799)
AKIYAMA Shingo Faculty of Humanities, Toyama Univ., Professor, 人文学部, 教授 (00126484)
SAKAI Hideo Faculty of Science, Toyama University, Research Assistant, 理学部, 助手 (30134993)
|Project Period (FY)
1984 – 1986
Completed (Fiscal Year 1986)
|Budget Amount *help
¥26,400,000 (Direct Cost: ¥26,400,000)
Fiscal Year 1986: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1985: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1984: ¥21,800,000 (Direct Cost: ¥21,800,000)
|Keywords||Secular variation of Geomagnetic field / Geomagnetic Excursion / Detrital Remanent Magnetization / 地震活動による再磁化 / 地震動による再帯磁|
We studied on the following three subjects to accomplish the purpose of this study.
1) Completion of the pre-historic geomagnetic secular variation.
Paleomagnetic samples were collected from the stratified sedimentary strata at Oiso hilly area, Minami-Taikoyama I archeological site and five active fault trench excavation sites. The results of the paleomagnetic measurements clarified the brief geomagnetic secular variation of the past 12,000 years.
2) Archeomagnetic age dating.
It is found that the magnetization of sediments of the excavated ancient rice field are strong and stable enough for archeomagnetic age dating. The dating which we tried in this study will become an important method for the dating of the ancient rice field.
Sediments located very close to the active fault plane and suffered from a severe tectonic deformation were often remagnetized parallel to the geomagnetic field direction at the time of the faulting activity. It becomes possible, therefore, to date the paleo-earthquake by comparing the magnetic direction of sediments to the archeomagnetic secular variation curve.
3) Age dating of sediments by means of the geomagnetic excursions.
It is reported that the geomagnetic excursion occurred several times during the Brunhes Normal Polarity Epoch. Paleomagnetic samples collected from the paleolithic excavation site of Babadan A, and the Nishiyagi excavation site show anomalous magnetic directions at Horizons 19 and 29 of Babadan A site, and at the horizons Stratum IV of the Nishiyagi site. From the similarity of the virtual geomagnetic pole path, the stratum IV of the Nishiyagi site might be correlated to the Ina I Excursion. Horizons 19 and 29 of the Babadan A site should be correlated to two of the following four excursions, that is, the Ina I Excursion, the Ina II Excursion, the Blake Event and Biwa I Event.
Report (2 results)
Research Products (13 results)