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Measurements of thermophysical properties of deep Earth materials under high pressure and high temperature

高压高温下地球深部物质热物性测量

基本信息

批准号：
14540401
负责人：
OSAKO Masahiro
金额：
$ 1.98万
依托单位：
National Science Museum
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Thermal diffusivity and thermal conductivity of major mantle candidate materials have been measured under pressures up to 8-10 GPa and temperatures to 1100 K, using a pulse-heating method of one-dimensional heat flow in a Kawai-type apparatus. The results show that the thermal conductivity or diffusivity of these major mantle minerals increases 3-4 % per 1 GPa, and that olivine likely preserves anisotropy in thermal diffusivity or conductivity throughout its stability in the mantle, i.e. down to 410 km depth. Garnet shows somewhat peculiar behavior of thermal conductivity or thermal diffusivity : their decrease by heating and increase by pressurizing are moderate compared to other dense oxides and olivine. Another major mantle material, pyroxene shows similar behavior of thermal conductivity or diffusivity to olivine. The present results of pressure dependence in thermal conductivity of diffusivity agree with previous experiments and theoretical predictions.As thermal diffusivity and t … More hermal conductivity are measured simultaneously, heat capacity is obtained by comparing these quantities. This study demonstrates a novel aspect of mineral physics : that the heat capacity of mantle materials under pressure could be determined experimentally. Heat capacities of olivine and garnet at room temperature are within 5 % of previously reported values. Moreover, the heat capacities for the three crystallographic directions in olivine are consistent within 6 %, which shows the adequacy of the present method for thermal diffusivity and conductivity. Under high pressures, heat capacities have slightly lower values to those at zero pressure. This is consistent with the identity of thermodynamics for changes in heat capacity under pressure.For future study, the pressure range will exceed 15 GPa, which is equivalent to those at the bottom of the upper mantle, and measurements of marked precision are hope to be performed with reduction of systematic errors probably derived from mechanical defect or deformation of the sample assembly by compression. Less

在Kawai型装置上，用一维热流脉冲加热法测量了主要地幔候选材料在压力8-10 GPa、温度1100 K下的热扩散率和热导率。结果表明，这些主要地幔矿物的热导率或扩散率每增加1 GPa增加3- 4%，并且橄榄石可能在其在地幔中的整个稳定过程中保持热扩散率或热导率的各向异性，即向下至410 km深度。石榴石显示出一些特殊的行为的导热系数或热扩散系数：它们的减少由加热和增加由加压是温和的相比，其他致密的氧化物和橄榄石。另一种主要的地幔物质，辉石显示出与橄榄石相似的热导率或扩散率行为。扩散系数与压力关系的研究结果与前人的实验结果和理论预测相一致。 ...更多信息同时测量导热系数，通过比较这些量得到热容。这项研究展示了矿物物理学的一个新方面：地幔物质在压力下的热容可以通过实验确定。橄榄石和石榴石在室温下的热容量在以前报道的值的5%以内。此外，橄榄石的三个结晶方向的热容是一致的6%以内，这表明本方法的热扩散率和电导率的适当性。在高压下，热容的值略低于零压下的值。这与压力作用下热容变化的热力学一致性是一致的，未来的研究压力范围将超过15 GPa，相当于上地幔底部的压力，并希望能进行高精度的测量，减少由于机械缺陷或样品组件压缩变形而可能带来的系统误差。少