MANTLE CONVECTION, PLATE TECTONICS, AND VOLCANISM ON HOT EXO-EARTHS
MANTLE CONVECTION, PLATE TECTONICS, AND VOLCANISM ON HOT EXO-EARTHS
复制标题
热地外地球上的地幔对流、板块构造和火山活动
DOI：
10.1088/2041-8205/736/1/l15
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
E. Gaidos
中科院分区：
文献类型：
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作者：
Joost van Summeren;C. Conrad;E. Gaidos
最近发现的靠近轨道的系外行星的表面温度应该在几百到几千开尔文之间。它们可能被潮汐锁定，并围绕其母星同步旋转，如果没有大气层，则在永久的昼夜之间有数百至数千开尔文的表面温度差异。我们研究了地球质量的行星的表面温度升高和强烈的表面温度对比的影响（1）地幔对流的模式，（2）构造体制，（3）部分熔融的速率和分布，使用数值模拟地幔对流与复合粘性/假塑性流变学。我们的模拟表明，如果一个接近的岩石系外行星缺乏大气层来重新分配热量，1000 K的表面温度对比可以保持一个不对称的程度1模式的地幔对流，其中行星的表面移动优先向俯冲带在寒冷的夜晚一侧。行星表面的特点是半球的二分法，在夜晚一侧有板块状的构造，在白天一侧有一个不断演变的移动的盖子，表面变形弥漫，火山活动活跃。如果火山释气建立了大气层并重新分配热量，板块构造在全球范围内被弥漫的表面变形所取代，火山活动加速并在行星表面分布得更加均匀。
Recently discovered exoplanets on close-in orbits should have surface temperatures of hundreds to thousands of Kelvin. They are likely tidally locked and synchronously rotating around their parent stars and, if an atmosphere is absent, have surface temperature contrasts of many hundreds to thousands of Kelvin between permanent day and night sides. We investigated the effect of elevated surface temperature and strong surface temperature contrasts for Earth-mass planets on the (1) pattern of mantle convection, (2) tectonic regime, and (3) rate and distribution of partial melting, using numerical simulations of mantle convection with a composite viscous/pseudo-plastic rheology. Our simulations indicate that if a close-in rocky exoplanet lacks an atmosphere to redistribute heat, a ≳400 K surface temperature contrast can maintain an asymmetric degree 1 pattern of mantle convection in which the surface of the planet moves preferentially toward subduction zones on the cold night side. The planetary surface features a hemispheric dichotomy, with plate-like tectonics on the night side and a continuously evolving mobile lid on the day side with diffuse surface deformation and vigorous volcanism. If volcanic outgassing establishes an atmosphere and redistributes heat, plate tectonics is globally replaced by diffuse surface deformation and volcanism accelerates and becomes distributed more uniformly across the planetary surface.