2010 Fiscal Year Final Research Report
Ab initio investigations on the high-pressure and temperature elasticity of calcium silicate perovskite
| Project/Area Number |
21740379
|
|---|
| Research Category |
Grant-in-Aid for Young Scientists (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Petrology/Mineralogy/Science of ore deposit
|
|---|
| Research Institution | Ehime University |
|---|
Principal Investigator |
TSUCHIYA Taku Ehime University, 地球深部ダイナミクス研究センター, 教授 (70403863)
|
|---|
| Project Period (FY) |
2009 – 2010
|
| Keywords | 地球・惑星内部構造 / 地殻・マントル物質 / 第一原理計算 |
|---|
| Research Abstract |
CaSiO_3 perovskite is one of major lower mantle constituent minerals, and it is important to understand its physical properties to clarify the Earth's deep structure and chemistry in detail. In this study, constant-temperature ab initio molecular dynamics simulations were performed with careful attention to the numerical accuracy for an 80-atoms supercell with applying a fine k-points sampling mesh. Results clarified that CaSiO_3 perovskite has at most 39% smaller in shear modulus, and thus at most 22% slower in shear velocity, than those reported in previous studies. Seismic velocities of typical mantle rocks modeled based on the obtained results indicated that the basaltic rock containing many CaSiO_3 perovskite has the velocity substantially slower than previous estimations. It was found from these results that typical properties observed in the lower mantle such as the weak S-velocity anomaly and the anticorrelation between S and bulk velocities can be reconciled by chemical heterogeneity produced by subducted oceanic slabs not by lateral temperature heterogeneity.
|
