Geofluid activities and partial melting accompanied by mass transfer in continent collision zones

2016 Fiscal Year Final Research Report

• Project/Area Number: 26400513
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Kyoto University
• Principal Investigator: Kawakami Tetsuo 京都大学, 理学研究科, 准教授 (70415777)
• Co-Investigator(Renkei-kenkyūsha): MIYAKE Akira 京都大学, 大学院理学研究科, 准教授 (10324609)
• Research Collaborator: HIGASHINO Fumiko 東北大学, 大学院環境科学研究科, 学振PD ; HIRATA Takafumi 東京大学, 大学院理学系研究科, 教授 (10251612) ; HIRAJIMA Takao 京都大学, 大学院理学研究科, 教授 (90181156) ; ITO Shoichi 京都大学, 大学院理学研究科, 准教授 (60397023)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 地質学 / 地球化学 / 地殻流体 / 大陸地殻 / 部分溶融 / 花崗岩形成論 / 物質循環

Outline of Final Research Achievements

Boron-bearing aqueous fluid activities were commonly recorded in the unmelted metamorphic rocks formed at lower crustal depths in the Himalayas. Salinity estimate of such fluids using mineral compositions such as tourmaline yielded almost equivalent value to sea water. On the other hand, in the Lützow-Holm Bay and Sor Rondane Mountains in Antarctica where lower crustal rocks of ca. 600 Ma collision zone is exposed, Cl-rich fluid activities were detected not during the retrograde metamorphic stage but also during prograde metamorphism at the depth of middle to lower crust. It became clear that in addition to Cl-bearing external fluid infiltration, partial melting played an important role in elevating the Cl concentration in the coexisting fluid. Partial melting can be a potentially important factor controlling the difference of fluid compositions observed in the Himalayas and Antarctica.

Free Research Field

岩石学