J-GLOBAL ID:200904074956300943  Research Project code:0450021930 Update date:Nov. 08, 2004

Experiment of melting mantle-peroxynitrite under high temperature and high pressure and formation of magma

Study period:2003 - 2004
Research overview:
Formation of magma caused by partial melting of mantle substances is one of the essential processes related to heat balance of the earth. Quantitative understanding of the mechanism is inevitable for elucidating evolution of the earth. The mainstream of former studies on formation of magma was based on approximation that mantle consisted of homogeneous peridotite. However, actual mantle is inhomogeneous and it is known that rocks being more maffick (poor of MgO) like peroxynitrite, eccrogyte and gabro exist in a ratio not to be neglected. It is conceivable that these maffick rocks (hereafter, called as peroxynitrite in a lump) are more greatly related to formation of magma than that thought from the ratio of existence because of lower temperature of their melting points in general than that of mantle peridotite. Also, from geochemical studies of magma extruded out of hot spots and central sea ridges, a large number of models have been proposed to state that peroxynitrite is related to formation of magma at these sites. Accordingly, for understanding the mechanism of mantle formation in the earth, it is necessary to know actual conditions of melting of peroxynitrite in mantle. However, there are a limited number of high-temperature and high-pressure experiments regarding melting of peroxynitrite, and almost no understanding of the role of peroxynitrite in magma has proceeded. The purpose of this study is to accumulate fundamental data of experimental petrology, which become necessary for understanding partial melting of peroxynitrite in mantle quantitatively. We execute melting experiments of a plurality of peroxynitrite having typical composition by using a high-temperature and high-pressure generation equipment to elucidate relation between a molten phase of peroxynitrite and a temperature-pressure condition to melt peroxynitrite under conditions without water or with volatile components (water, carbon dioxide) and we determine a chemical composition of melt formed. Then, by using these experimental data, we analyze conditions of forming magma at hot spots and at central sea ridges to construct a model of magma formation, in which peridotite and peroxynitrite have their roles.
Project Organization (1):
  • (C013000000)
Research program: Grant-in-Aid for Scientific Research
Ministry with control over the research :
Ministry of Education, Culture, Sports, Science and Technology

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