| Project/Area Number |
12640467
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Petrology/Mineralogy/Science of ore deposit
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
SATO Hiroki Graduate School of Science, Dept. of Earth and Space science, Associate Professor, 大学院・理学研究科, 助教授 (50215828)
|
|---|
| Project Period (FY) |
2000 – 2002
|
| Project Status |
Completed (Fiscal Year 2002)
|
| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
|
|---|
| Keywords | mineral-fluid system / hydrothermal / partial melt / elastic-wabe velocity / Vp / Vs / low-velocity zone / velocity structure / rock physics / Vs-Vp / Vsダイヤグラム / 蛇紋岩 / 含水鉱物 / H_2O流体 / 岩石-流体系の微細構造 / 流体分布の解析 / 脱水過程 / フラクタル解析 / 統計解析 / 対数正規分布 / 面構造 / 流動組識 / 方解石粒子 / XY,XZ,YZ面 / 相関関係 |
|---|
| Research Abstract |
H_2O-fluid distributions in rocks critically control rock textures and microtectonics. We have shown that physical properties of fluid-bearing rocks can be estimated from the properties of mineral-fluid systems. The properties of the crust and the upper mantle are, therefore, estimated from the properties of quarts-feldspar-fluid, pyroxene-amphibole-fluid, and olivine-pyroxene-fluid systems. Here fluid is either H_2O or partial melt.
In the Japan subduction zone, H_2O or partial melt causes low velocity in the crust and the upper mantle : Elasticity data of crustal and mantle minerals and of H_2O and silicate melts have been determined at high pressures and temperatures. Those data can be used to estimate elastic-wave velocities of fluid-bearing crust and mantle rocks.
P-wave to S-wave velocity ratios, Vp/Vs, of mineral-melt systems are higher than those of mineral-H_2O systems. This is because the bulk modulus of silicate melt is about an order of magnitude larger than that of H_2O. Seismic tomographic studies have shown that Vp/Vs is generally high in the upper mantle low-velocity zone, indicating the presence of partial melt. On the other hand, Vp/Vs is low in the upper crustal low-velocity zone. We suggest that H_2O fluid causes low velocity in the upper crust.
|
