Maturing processes of arc MOHO deduced from ophiolites

2015 Fiscal Year Final Research Report

• Project/Area Number: 25302012
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 海外学術
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Kanazawa University
• Principal Investigator: Morishita Tomoaki 金沢大学, 自然システム学系, 教授 (80334746)
• Co-Investigator(Kenkyū-buntansha): SUZUKI Katsuhiko 国立研究開発法人海洋研究開発機構, グループリーダー (70251329) ; YOSHIKAWA Masako 京都大学, 理学系研究科, 教務補佐 (00378605) ; ISHIKAWA Akira 東京大学, 総合文化研究科, 助教 (20524507) ; TANI Kenichiro 独立行政法人国立科学博物館, 地学研究部, 研究員 (70359206)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 島弧火成活動 / 下部地殻 / 上部マントル / モホロビチッチ不連続面 / メルトー岩石反応 / 島弧変成作用

Outline of Final Research Achievements

I summarize results from two ophiolites (the northern Oman ophiolite of Oman and the Mirdita Ophiolite of Albania) and ophiolitic localities (the Talkeetna massif, Alaska) in order to investigate the maturing processes of arc systems, such as Nascent, Young and Mature stages, respectively. The main conclusions are as follows: (1) the high frequency of highly refractory harzburgite (+dunite and chromitite) caused by influx of slab-derived fluids, (2) silica enrichments resulting in increasing of pyroxenites in peridotites. These can be good indicators of arc-related magmatic modifications in the mantle. In Mature stage (Talkeetna), ultramafic rocks are formed by metamorphism from plagioclase-bearing crustal rocks. These rocks can be related those are delaminated from the lower crust part to the mantle.

Free Research Field

マントル岩石学