Reference material for U-Pb geochronology of carbonate minerals and the mineralogical and geochemical characteristics of calcite

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04008
• 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: Akita University
• Principal Investigator: Fukuyama Mayuko 秋田大学, 理工学研究科, 准教授 (40630687)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 方解石 / 炭酸塩鉱物 / LA-ICP-MS / U-Pb年代測定 / 局所分析 / 放射年代

Outline of Final Research Achievements

In-situ U-Pb dating of carbonate minerals can be applied to understand the timing of vein-type mineralization, fault movements, and other geological events forming calcites, which are difficult to be dated by other methods. However, it is often difficult to obtain reliable estimated ages of calcite because calcite usually contains high common Pb content. In this study, I examined various calcites from various occurrences. In this study, I present that the travertine PKC-1 can be a suitable reference material for the dating of calcite of Quaternary age. The index of calcite using the elemental distribution in calcite and elemental concentration is also established to understand the U-Pb isotopic system of calcite.

Free Research Field

岩石学

Academic Significance and Societal Importance of the Research Achievements

炭酸塩鉱物である方解石は、石灰岩の主要な構成鉱物であるだけでなく、幅広い岩石中に普遍的に産出し、岩石の割れ目を充填する脈として、また断層の形成に伴って断層岩中にも産出する。このような脈や岩石にはジルコンのような年代測定が可能な珪酸塩鉱物が存在することは稀であり、方解石の形成年代を知ることは、その割れ目や断層の形成年代に制約を与えることとなる。つまり、方解石の年代測定は、その産出状況から、他の年代測定法では得ることができない年代情報を与えてくれる点で重要である。