A structural petrological study of the subduction boundary: the example of the Sanbagawa belt in SW Japan

2015 Fiscal Year Final Research Report

• Project/Area Number: 24244079
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geology
• Research Institution: Nagoya University
• Principal Investigator: Wallis Simon 名古屋大学, 環境学研究科, 教授 (30263065)
• Co-Investigator(Kenkyū-buntansha): ENAMI Masaki 名古屋大学, 年代測定総合研究センター, 教授 (20168793) ; MIZUKAMI Tomoyuki 金沢大学, 自然システム系, 助教 (80396811) ; AOYA Mutsuki 徳島大学, 大学院ソシオ・アーツ・アンド・サイエンス研究部, 准教授 (90415638)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: Sanbagawa / Mantle wedge / Subduction boundary / brucite

Outline of Final Research Achievements

Deformation of mantle rocks at depths of several 10s km in subduction zones is thought to be responsible for inducing large scale mantle convection. It is not possible to study such regions directly. However, it is possible to gather valuable information on these domains by studying geological units that were once part of the subduction boundary region and have since been brought to the earth's surface by tectonic movements. Particularly clear examples of this are the mantle units of the Sanbagawa belt. Structural petrological studies reveal the former widespread presence of brucite. The presence of brucite in the mantle i) causes a drastic weakening and will likely strongly affect the depth of coupling between the mantle and slab; and ii) controls the hydration dehydration reactions and hence fluid pressure.

Free Research Field

Structural geology and petrology