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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The relationship between Martian gravity and topography
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The relationship between Martian gravity and topography

机译：火星重力与地形之间的关系

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The relationship between gravity and topography of various regions of Mars is used to estimate their effective elastic thicknesses T_e using direct measurements of line of sight velocity, rather than spherical harmonic coefficients. Estimates of T_e vary from 70 km for Tharsis, 29 km for Elysium, to 14.5 km for the southern hemisphere, and show that the thickness of the Martian lithosphere increases with age as the radioactive isotopes of K, Th, and U decay. A simple parameterised model of the convective thermal history is used to estimate the temperature structure of the lithosphere, and shows that the base of the elastic layer has a temperature of 300 ± 50 ℃, or similar to the value for terrestrial continents. In both cases the rheology is probably affected by the presence of water. The short wavelength behaviour of the gravity field allows the density of the rocks that form the topography to be estimated, and gives values of about 3.0 Mg/m~3 for Tharsis and Elysium. This value is substantially greater than that of 2.7 Mg/m~3 obtained for Earth, and is in agreement with estimates from SNC (Shergottites-Nahklites-Chassigny) meteorites of 3.3 Mg/m~3. The density of the topography of Valles Marineris is only 2.35 Mg/m~3, and suggests that ice may be present below the surface. In the heavily bombarded southern hemisphere, isostatic compensation occurs at wavelengths as short as 700 km, which requires the effective compensation depth to be no more than 10 km. The gravity field with wavelengths greater than 1500 km may be supported dynamically, by a plume rising beneath the Tharsis region. The difference in temperature between the solidus and the present areotherm is less than 250 ℃, so melt generation can occur in rising plumes.
机译：火星各个区域的重力和地形之间的关系用于通过视线速度而不是球谐系数的直接测量来估算其有效弹性厚度T_e。 T_e的估计值从塔尔西斯（Tharsis）的70 km，极乐世界（Elysium）的29 km到南半球的14.5 km不等，并且表明随着K，Th和U放射性同位素的衰变，火星岩石圈的厚度随年龄增加。利用对流热历史的简单参数化模型估算岩石圈的温度结构，结果表明弹性层的底部温度为300±50℃，与陆地温度相似。在这两种情况下，流变性都可能受水的影响。重力场的短波长行为使得可以估计形成地形的岩石的密度，并且对于Tharsis和Elysium给出大约3.0 Mg / m〜3的值。该值大大高于从地球获得的2.7 Mg / m〜3的值，并且与SNC（Shergottites-Nahklites-Chassigny）陨石的3.3 Mg / m〜3的估计值一致。 Valles Marineris的地形密度仅为2.35 Mg / m〜3，表明表面下可能存在冰。在遭受严重轰炸的南半球，等静波补偿发生在短至700 km的波长处，这要求有效的补偿深度不超过10 km。波长大于1500 km的重力场可以由塔里西斯地区下方上升的羽流动态地支撑。固相线与当前等温线之间的温度差小于250℃，因此在上升的羽流中会产生熔体。

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