Thermal and material recycling process in the upper mantle beneath off-arc region

2015 Fiscal Year Final Research Report

• Project/Area Number: 23740398
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Petrology/Mineralogy/Science of ore deposit
• Research Institution: Osaka City University (2014-2015); Japan Agency for Marine-Earth Science and Technology (2011-2013)
• Principal Investigator: Sakuyama Tetsuya 大阪市立大学, 大学院理学研究科, 准教授 (80553081)
• Project Period (FY): 2011-04-28 – 2016-03-31
• Keywords: アルカリ玄武岩 / プレート内火山 / スタグナントスラブ / ユーラシア大陸東縁部 / 海洋地殻 / 堆積物 / マントル遷移層 / 超背弧域

Outline of Final Research Achievements

Stagnation of the subducted Pacific slab in the mantle transition zone beneath eastern China has been imaged by seismic tomography. Late Cenozoic basaltic volcanoes lying above the stagnant slab, are distributed throughout eastern China. These basalts are rich in alkaline and incompatible trace elements that are typically associated with oceanic island basalts (OIBs). Such geochemical similarities between the basalts in eastern Asia and typical OIBs have led some researchers to conclude that the Chinese basalts originated from the upwelling of mantle, independent of a stagnant slab. According to the results of high-pressure experiments, melting of the stagnant slab could occur if the slab contains adequate amounts of H2O or CO2. In this study, we presented geochemical and petrological evidence that melts from the igneous layers in the stagnant Pacific plate slab have contributed to the source composition of basalts erupted in eastern China.

Free Research Field

マグマ学