Geochemical variation in the subducting Pacific Plate and responses of the volcanic arc lavas

2014 Fiscal Year Final Research Report

• Project/Area Number: 24340136
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Science of ore deposit
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: KIMURA Jun-Ichi 独立行政法人海洋研究開発機構, 地球内部物質循環研究分野, 分野長代理 (30241730)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 化学組成 / 同位体組成 / 沈み込み / 太平洋プレート / 島弧火山岩

Outline of Final Research Achievements

The Principal Investigator (PI) has measured 42 elements and Sr-Nd-Hf-Pb isotope compositions of the Pacific Plate materials subducting beneath the Japanese Islands. Using the data, PI has calculated compositions the fluids released from the Pacific Plate beneath Japan island arcs using a geochemical/petrological mass balance model. The released fluids were added to the mantle beneath the arcs and generated magmas; the same model also calculated these magma compositions. The observed compositions of magmas erupted on the NE and SW Japan arcs were compared with the calculated magma compositions. The geophysical parameters that control the magma compositions were also examined. The model successfully reproduced the observed magma compositions with reasonable geophysical parameters from geophysical observations. These studies finally revealed that the Plate temperature principally controls magma composition and magma production rate.

Free Research Field

岩石学・地球化学・火山学