Shock compression of stishovite and melting of silica at planetary interior conditions
Shock compression of stishovite and melting of silica at planetary interior conditions
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DOI：
10.1126/science.1261507
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发表时间：
2015-01-23
期刊：
影响因子：
56.9
通讯作者：
Jeanloz, R.
中科院分区：
文献类型：
--
作者：
Millot, M.;Dubrovinskaia, N.;Jeanloz, R.
在行星内部深处，极高的密度、压力和温度极大地改变了组成物质的性质。特别是，固体在压力下熔化之前能够承受多少热量，对于确定行星的内部结构和演化至关重要。我们报道了在熔融石英、α - 石英和斯石英上进行的激光驱动冲击实验，这些实验在前所未有的条件下得出了状态方程和电子电导率数据，并表明在500吉帕的压力下，二氧化硅的熔化温度上升到8300开尔文，这与5倍地球质量的超级地球的核幔边界条件相当。我们发现，地幔硅酸盐和地核金属在500到700吉帕以上具有相当的熔化温度，这可能有利于大型类地行星存在长期存在的岩浆海洋，这对这类行星内部深处的硅酸盐岩浆层中行星磁场的产生具有重要意义。
Deep inside planets, extreme density, pressure, and temperature strongly modify the properties of the constituent materials. In particular, how much heat solids can sustain before melting under pressure is key to determining a planet's internal structure and evolution. We report laser-driven shock experiments on fused silica, alpha-quartz, and stishovite yielding equation-of-state and electronic conductivity data at unprecedented conditions and showing that the melting temperature of SiO2 rises to 8300 K at a pressure of 500 gigapascals, comparable to the core-mantle boundary conditions for a 5-Earth mass super-Earth. We show that mantle silicates and core metal have comparable melting temperatures above 500 to 700 gigapascals, which could favor long-lived magma oceans for large terrestrial planets with implications for planetary magnetic-field generation in silicate magma layers deep inside such planets.