[2poster95-96] GG-10．堆積地質

[G-P-29] 青森県下北半島の海岸堆積物の磁気的手法による法地質学研究

*川村 紀子¹、松下 拓哉¹、板宮 裕実²、杉田 律子²、山崎 俊嗣³ (1. 海上保安庁海上保安大学校、2. 警察庁科学警察研究所、3. 東京大学大気海洋研究所)

キーワード：

法地質学、海岸堆積物、岩石磁気、環境磁気、科学捜査

Magnetic analysis of soil and sediment in room temperature is a non-destructive method, therefore it has been used geological and environmental investigations. Many illegal activities have been occurred in beach. In order to verify the usefulness of magnetic analysis in forensic research, the beach sediments were collected at nine sites from Shimokita Peninsula in Japan, were measured, and discussed whether the results reflect to regional characteristics. Concentration-dependent magnetic parameters: low-field magnetic susceptibility, anhysteretic remanent magnetization (ARM), and isothermal remanent magnetization (IRM) indicated relative higher values at sites where were located near the sedimentary mines of titanium (Ti) and iron (Fe). Results of thermo magnetometry suggest that magnetic carriers of the sediments are mainly magnetite (Fe₃O₄), and pyrrhotite (Fe₇S₈) is recognized around Ti-Fe mines sites. Result of the concentration-dependent magnetic parameter imply that the amount of magnetic minerals in the beach sediments will be regionally characterized. The IRM curves in low temperature are also characteristic per the sampling sites. The comparison of the magnetic grain size parameters to the Curie points also could characterize per the sampling sites. We think that magnetic analysis of the beach sediments will be an effective method to estimate the provenance of beach sediments in forensic research.