Thermochemical evolution of Mercury's interior
Thermochemical evolution of Mercury's interior
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水星内部的热化学演化
DOI：
10.1002/jgre.20168
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
D. Breuer
中科院分区：
文献类型：
--
作者：
Tosi N;M. Grott;A.-C. Plesa;D. Breuer
现在可以利用信使号航天器进行的大量观测来更好地了解水星内部的演化。利用最近对内部结构、表面成分、火山和构造历史的限制，我们模拟了地球的热和岩浆演化。我们基于一维参数化模型运行了大量蒙特卡罗模拟，涵盖了广泛的参数。我们通过 2D 圆柱和 3D 球面几何中的选定计算来补充这些模拟，这证实了参数化方法的有效性，并使我们能够进一步了解地幔对流的时空演化。已经考虑了 1940 km、2040 km 和 2140 km 的核心半径，虽然在前两种情况下，几个模型满足观测约束，但没有找到半径 2140 km 的可接受模型。典型的热演化情景包括地幔加热的初始阶段，伴随着行星膨胀和大量部分熔化的产生。 2 Gyr 之后的演化特征是长期冷却，其大致以恒定速率进行，这意味着行星收缩今天应该持续进行。大多数模型预测地幔对流将在 3-4 Gyr 后停止，表明水星可能不再动态活跃。最后，假设观测到的放射性元素的表面丰度能够代表整个地壳，我们确定了 35-62 ppb Th、20-36 ppb U 和 290-515 ppm K 的大量硅酸盐浓度，与其他类地行星的浓度类似。
A number of observations performed by the MESSENGER spacecraft can now be employed to better understand the evolution of Mercury's interior. Using recent constraints on interior structure, surface composition, volcanic and tectonic histories, we modeled the thermal and magmatic evolution of the planet. We ran a large set of Monte Carlo simulations based on one‐dimensional parametrized models, spanning a wide range of parameters. We complemented these simulations with selected calculations in 2‐D cylindrical and 3‐D spherical geometry, which confirmed the validity of the parametrized approach and allowed us to gain additional insight into the spatiotemporal evolution of mantle convection. Core radii of 1940 km, 2040 km, and 2140 km have been considered, and while in the first two cases several models satisfy the observational constraints, no admissible models were found for a radius of 2140 km. A typical thermal evolution scenario consists of an initial phase of mantle heating accompanied by planetary expansion and the production of a substantial amount of partial melt. The evolution subsequent to 2 Gyr is characterized by secular cooling that proceeds approximately at a constant rate and implies that planetary contraction should be ongoing today. Most of the models predict mantle convection to cease after 3–4 Gyr, indicating that Mercury may be no longer dynamically active. Finally, assuming the observed surface abundance of radiogenic elements to be representative for the entire crust, we determined bulk silicate concentrations of 35–62 ppb Th, 20–36 ppb U, and 290–515 ppm K, similar to those of other terrestrial planets.