Estimation and evaluation of magma flux for Cretaceous large silicic caldera cluster

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14023
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Sato Daisuke 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 主任研究員 (80586595)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: カルデラ / 白亜紀 / 火成活動 / 西南日本 / 火山 / ジルコン年代

Outline of Final Research Achievements

Cretaceous volcanic rocks are widespread throughout around Hyogo Prefecture and are composed mainly of silicic pyroclastic flow deposits with minor amounts of clastic rocks. In this study, I attempted to estimate the volcanic erupted rate based on geological survey and radiometric dating. The volcanic rocks are often intruded by the steeply dipping dikes (or faults), which are distributed in along boundaries between the volcanic rocks and the basement rocks, suggesting that many of them were probably caldera volcanoes at that time. The zircon U-Pb ages of the volcanic rocks around Hyogo Prefecture are 95-72 Ma in the southern part, 84-71 Ma in the central part and 68-63 Ma in the northern part, with ages concentrated of ca 85-80 Ma in the southern part and ca 80-74 Ma in the central part.

Free Research Field

地質学

Academic Significance and Societal Importance of the Research Achievements

白亜紀火山岩類・深成岩類は西南日本に広く分布するが，ジルコンU-Pb年代の報告は，深成岩類に対して火山岩類は限定的である．本研究で，白亜紀カルデラ火山群の当時の沈み方向と同じ西南日本の南北方向の火山活動の時期が明らかになることは，アジア東縁地域における白亜紀火成活動のマグマプロセス及び時空変遷に制約を与え，解明に向けて大きな貢献となる．