Petrologic structure of the strain concentration zone along the eastern margin of Japan Sea

2014 Fiscal Year Final Research Report

• Project/Area Number: 23340153
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geology
• Research Institution: Yokohama National University
• Principal Investigator: MASAHIRO Ishikawa 横浜国立大学, 環境情報研究科(研究院), 教授 (70232270)
• Co-Investigator(Kenkyū-buntansha): SATO Hiroshi 東京大学, 地震研究所, 教授 (00183385) ; BAN Masao 山形大学, 理学部, 教授 (50208724)
• Project Period (FY): 2011-04-01 – 2015-03-31
• Keywords: ひずみ集中帯 / 地殻 / 下部地殻 / 地殻構造 / 日本海東縁

Outline of Final Research Achievements

This study presents a new view of the constituent rocks in the lower crust and uppermost mantle beneath the strain concentration zone along the eastern margin of Japan Sea of northeast Japan based on the P- and S-wave velocities obtained by seismic tomography and comparisons with the experimentally determined velocities of rock-forming minerals. We inferred that orthpyroxene exist in the high velocity lower crust as a main constituent mineral beneath the the eastern margin of Japan Sea of northeast Japan, underlain by high Vp/Vs anomaly (clinopyroxenite) in the uppermost mantle. These inferences suggest that the Miocene rift-related magmatism produced the high velocity lower crust and the high Vp/Vs uppermost mantle. Considering the regional distribution of these unusual uppermost mantle rocks, strain concentration is inferred to have related with rheological property of the unusual uppermost mantle.

Free Research Field

岩石物性