2022 Fiscal Year Final Research Report
Saline fluid activity in the lower continental crust of the collision zones
| Project/Area Number |
19H01991
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Review Section |
Basic Section 17040:Solid earth sciences-related
|
|---|
| Research Institution | Kyoto University |
|---|
Principal Investigator |
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
坂田 周平 東京大学, 地震研究所, 助教 (20772255)
M Satish‐Kumar 新潟大学, 自然科学系, 教授 (50313929)
東野 文子 京都大学, 理学研究科, 助教 (60816685)
|
|---|
| Project Period (FY) |
2019-04-01 – 2023-03-31
|
| Keywords | 大陸地殻 / 塩水流体 / 大陸衝突帯 / 沈み込み帯 / 部分融解 / 剪断帯 / 変成岩 / 花崗岩 |
|---|
| Outline of Final Research Achievements |
We conducted geological survey of the Sor Rondane Mountains (SRM) as a part of the 61st Japanese Antarctic Research Expedition. We constructed temperature-pressure-time paths of the metamorphic rocks in the SW part of the SRM, and obtained several clockwise paths accompanied with a nearly isothermal decompression followed by cooling and decompression, which are different from previous studies reporting counterclockwise paths. This decompression was dated to have started at 550 Ma in some areas. Tectonic model for the SRM formation needs to be reconsidered.
The fractures filled with Cl-rich hydrous minerals are found throughout the SRM. Petrology and isotope geochemistry of these fractures and their host rocks have shown that the fractures were formed by the infiltration of saline fluids released from granitoid magmas. The duration of saline fluid infiltration was shorter than a half day. The salinity of the fluid was likely higher than that in the subduction zone environment.
|
| Free Research Field |
地球惑星科学
|
| Academic Significance and Societal Importance of the Research Achievements |
セール・ロンダーネ山地は約6-5億年前のゴンドワナ大陸形成時のテクトニクスを理解するうえで鍵になる地域に位置するが、その形成過程を制約するのに役立つ変成岩類の温度-圧力-時間履歴が広い範囲から得られ、従来考えられていた以上に複雑な履歴を考える必要がでてきた。また、同山地や比較対象地域であるヒマラヤおよび沈み込み帯環境における塩水流体活動の研究成果は、活動的大陸地殻下部や大規模剪断帯における塩水流体活動の重要性を示しており、現在のプレート収斂域の地殻深部やマグマだまりの周辺で起きている流体活動の実態を理解し、地球物理学的観測データと比較するうえで重要な物質科学的情報を提供している。
|
