| 講演要旨(和文) | | 物理探査は地下から表層までの累積情報を測定する手法であり，岩石物性測定は物理探査の結果を解釈する上で非常に有効である．しかし，物理探査の実施と並行して岩石物性情報を調べられる事があまりなかった．そこで今回，北海道の武佐岳地域で採取した岩石の物性値測定実験を行った．当該地域では，独立行政法人石油天然ガス・金属鉱物資源機構（JOGMEC）が平成29年に高分解能空中磁気探査を実施している．JOGMECは同探査に加え現地での地表地質踏査を行い，大凡の磁化方向の測定を実施しているが，岩石の磁化方向の詳細は不明であった．そのため，採取された岩石を整形し実験室において詳細に測定し，その結果と上記の探査で明らかにされた空中磁気異常分布との比較検討を行った．この結果，採取された岩石試料の初生磁化は全て逆帯磁を示し，露頭付近に卓越する顕著な低磁気異常分布の原因が逆帯磁岩石の分布に対応する可能性を裏付けた. |
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| | 講演要旨(英文) | | Geophysical exploration can measure cumulative information from the underground to the surface layer, and rock property measurement is very effective in interpreting the results of geophysical exploration. However, rock property information has not been examined intensively in parallel with geophysical exploration so far. In this study, we measured rock properties of volcanic rocks in the Musadake area of Hokkaido as a case study. In this area, the Japan Oil, Gas and Metals National Corporation (JOGMEC) conducted a high-resolution aeromagnetic survey in 2017. In addition to the exploration, JOGMEC conducted a surface geological survey on site and measured the general direction of magnetization of outcrops as well as magnetic susceptibility. However, the detailed magnetic properties of the rocks were unknown. Therefore, the collected rocks were reshaped and their physical properties were measured in the laboratory, and the results were compared with the observed aeromagnetic anomalies. As a result, the initial magnetizations of all the rock samples after AF demagnetization showed a reverse direction, suggesting that the remarkable low magnetic anomalies near the outcrops can be attributed to the distribution of reversely magnetized rocks. |
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