A forensic geology application of magnetic analysis to the beach sediments collected from Shimokita Peninsula, Aomori Prefecture in Japan.

Abstract

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.