Rock magnetic studies in evaluating thermal history of hot springs in active volcanic areas: Case studies from Mn wad deposits in Hokkaido, Japan

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K03989
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: University of Toyama
• Principal Investigator: Kawasaki Kazuo 富山大学, 学術研究部都市デザイン学系, 准教授 (60624806)
• Co-Investigator(Kenkyū-buntansha): 酒井 英男 富山大学, 理学部, 客員教授 (30134993)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: マンガン土 / 鉱床 / 温泉水 / 火山 / 環境磁気

Outline of Final Research Achievements

This study shows that the major magnetic minerals in manganese wad sediments collected from the foot of either Komagatake and Asahidake volcanoes in Hokkaido are consistent regardless of depth from the pond bottom or locations of the core collection. The results indicate that there would have been no significant changes in volcanic conditions or the pathways of hot spring water since these manganese wads had precipitated from the hot springs by bacteria. Paleomagnetic and rock magnetic analyses of the Grum deposit in Canada indicate that the intrusion of the nearby Cretaceous Anvil batholith was not related to the formation of this deposit and that the ore genesis was associated with tectonic movements of the Jurassic age. These results show the effectiveness of paleomagnetism and rock magnetism in studying ore deposits, volcanism, and their relationships.

Free Research Field

古地磁気学・環境磁気学

Academic Significance and Societal Importance of the Research Achievements

一般的に火山活動の解明には，古文書や火山灰層・火山噴出物等の研究から火山噴火年代や噴火の様式を明らかにされる．一方，噴火を伴わない期間については，常時観測網が整備される以前の詳細な情報の取得は著しく困難である．本研究で得られた成果により，火山の状態の推定に温泉水から恒常的に沈殿する堆積物の岩石磁気特性解析が有効である新知見が得られ，火山学や資源地質学への新規手法としての展開が期待される．