权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Determination of thermal expansion coefficient of the major mantle minerals at high pressures and temperatures and estimation of adiabatic geotherm in the upper part of the mantle

地幔上部主要矿物热膨胀系数测定及地幔上部绝热地温估算

基本信息

批准号：
17204036
负责人：
KATSURA Tomoo
金额：
$ 32.36万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

We have measured unit cell volumets of the major mantle minerals, namely, olivine, wadsleyite and perovskite at high pressures and temperatures by means of in situ X-ray diffraction using a large-volume high-pressure and high-temperature apparatus installed at the synchrotron radiation facility, SPring-8. We have constructed the Mie-Grueneisen-Debye equations of state of these minerals by using the obtained data. In this procedure, we have used the bulk modulus, its pressure derivative and Debye temperature from the literatures, and estimated Grueneisen parameter gamma0 and its logarithmic volume dependence q. The estimated parameters are as follows: gamma0 = 1.40(1) and q = 2.2(1) for olivine, gamma0 =1.64(1) and q = 1.5(1) for wadsleyite. Gamma0 = 2.66(2) and q = 1.9(1) for perovskite. We have estimated thermal expansion coefficient of the major mantle minerals in the Earth's mantle using these parameters and those given by Katsura, et. Al. (2004). By assuming the adiabatic temperature gradient, the thermal expansion coefficient of olivine largely decreases with depth to 2.6 x 10(-5) /K at the 410-km depth. The thermal expansion coefficient increases associated with the olivine-wadsleyite-ringwoodite-perovskite transitions and decreasing with depth. As a result, the thermal expansion coefficient is nearly constant in the upper part of the mantle. The behavior of the adiabatic gradient is similar, and is nearly constant, that is, 0.4 K/km at the upper part of the mantle.

我们利用安装在同步辐射装置SPRING-8上的大体积高压高温装置，用原位X射线衍射法测量了主要地幔矿物橄榄石、黄铁矿和钙钛矿在高压和高温下的晶胞体积。利用所获得的数据建立了这些矿物的Mie-Grueneisen-Debai状态方程。在这个过程中，我们利用文献中的体积弹性系数、压力导数和德拜温度，估算了Grueneisen参数Gamma0及其与体积的对数关系q。估算的参数如下：橄榄石的Gamma0=1.40(1)和q=2.2(1)，黄闪石的Gamma0=1.64(1)和Q=1.5(1)。钙钛矿型：Gamma0=2.66(2)，Q=1.9(1)。利用这些参数和Katsura等人给出的参数，我们估算了地幔中主要地幔矿物的热膨胀系数。艾尔。(2004)。假设绝热温度梯度，橄榄石的热膨胀系数在410公里处随深度大幅度下降至2.6×10(-5)/K。热膨胀系数随橄榄石-水滑石-环木-钙钛矿转变而增大，随深度的增加而减小。因此，地幔上部的热膨胀系数几乎是恒定的。绝热梯度的变化规律相似，基本不变，即地幔上部的绝热梯度为0.4K/Km。