2000 Fiscal Year Final Research Report Summary
DIRECT OBSERVATION OF HYDROUS SILICATE MELTS IN HIGH TEMPERATURE AND PRESSURE CONSITIONS : UNDERSTANDING THE ROLE OF H2O IN MELTING OF THE EARTH'S MANTLE.
| Project/Area Number |
10554024
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B).
|
| Allocation Type | Single-year Grants |
|---|
| Section | 展開研究 |
|---|
| Research Field |
Petrology/Mineralogy/Science of ore deposit
|
|---|
| Research Institution | KYOTO UNIVERSITY |
|---|
Principal Investigator |
TATSUMI Yoshiyuki Kyoto Univ. Science, Professor, 大学院・理学研究科, 教授 (40171722)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAWAMOTO Tatsuniko Kyoto Univ. Science, Jyosyu, 大学院・理学研究科, 助手 (00303800)
|
|---|
| Project Period (FY) |
1998 – 2000
|
| Keywords | Diamond anvils / magma / high temperature / H2O / Infrared / high pressure |
|---|
| Research Abstract |
Knowledge of structures of magmas is important to model the evolution of the earth's interior. Much efforts had been made to understand structure of magmas by measuring properties of glasses quenched from high temperature and pressure conditions. Properties of silicates melts have been found to be different from those of quenched glasses. Therefore, the direct measurement of melts at high temperature and pressure conditions is desirable. Based on chemistry of partial melts of H2O-saturated mantle peridotite, we have suggested structures of hydrous melts should change drastically with an increasing pressure. For direct observations of magmas at high temperature and pressure conditions, Bassett's type externally heated DAC can be one of ideal tools because of its easy temperature control within a few degree C in a range to 1050 degree C.FTIR microscopy with this DAC is used to understand complete miscibility between H2O-rich melts and silicate-rich H2O fluids and also temperature depende
… More
nce of OH/H2O abundances in aluminosilicates and felsic magmas. A series of experiments of complete miscibility in H2O and an island arc andesite has been conducted in our laboratory. So, let's do this business with magmas relevant to mantle conditions. It is revealed that there is a difficulty to conduct experiments in mafic systems such as enstatite MgSiO3, diopside CaMgSi2O6, wollastonite CaSiO3, natural basalt, and high Mg andesites. When the glasses of those mafic compositions are heated with water in DAC, crystallization of pyroxene or amphibole takes place quickly at around 500 degree C.The crystals do not remelt and no melt of the system itself can be obtained in a temperature range to 1050 degree C.In order to obtain melts of these chemical compositions, higher temperature DAC should be used. Above 1050 degree C, diamond surfaces quickly transform to graphite. Internal heating method , which is able to heat samples uniformly and leave diamonds less hot, can be a better tool to investigate the mafic melts. Less
|
