High-resolution reconstruction of the ancient oceanographic environments based on the development of evaluating method of microscopic three-dimensional fabrics of sediments

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03704
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: Osaka Metropolitan University (2022-2023); Osaka Prefecture University (2021)
• Principal Investigator: Itoh Yasuto 大阪公立大学, 大学院現代システム科学研究科, 教授 (20285315)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 地質学 / 岩石磁気学 / 古環境 / 磁性流体

Outline of Final Research Achievements

This study aims at unraveling micro-scale fabrics of sedimentary rocks, which act as pathway of formation fluids such as crude oil and/or natural gas. Conventional methods lack three-dimensional quantitative evaluation of small fracture network within rocks. We utilized magnetite-laden colloid (ferrofluid) to delineate fracture networks. Under high pressure, ferrofluid invades into rocks along permeable fractures and indicates directions of migration of formation fluids. Microscopic observation of ferrofluid-treated rocks by using X-ray ST scanner depicts numerous colony of microfossils concealed in sediment particles, and shows process of oceanic anoxic events that are closely related with mass extinctions of the Earth's long history. Our multidisciplinary structural analysis has succeeded in visualization of significant fault systems within sedimentary basins along studied convergent margin of an oceanic plate.

Free Research Field

固体地球科学

Academic Significance and Societal Importance of the Research Achievements

海洋無酸素事変は、極めて温暖な気候下にあった白亜紀に頻発しており、温室効果ガスの増加による急激な温暖化と環境悪化が懸念される現在の地球と相通ずるところがある。その発生メカニズムを詳細かつ定量的な古生物学的分析で評価することは、持続可能な環境を如何にして維持していくかという喫緊の課題として極めて重要である。また、堆積岩ファブリックと緊密な関連を持つ断層の三次元ネットワークを評価することは、地震など自然災害が頻発する変動帯でどのように防災・減災の取り組みを進めるかという課題の解決に、直接資するものである。