The thermal structure and mechanical behavior of the martian lithosphere
The thermal structure and mechanical behavior of the martian lithosphere
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DOI：
10.1016/j.icarus.2020.113635
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发表时间：
2021
期刊：
影响因子：
3.2
通讯作者：
A. Jiménez‐Díaz;I. Egea-González;L. Parro;M. Tasaka;J. Ruiz
中科院分区：
文献类型：
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作者：
A. Jiménez‐Díaz;I. Egea-González;L. Parro;M. Tasaka;J. Ruiz
深入了解火星地壳和地幔的热和流变学性质是限制其岩石圈强度的基础，从而了解其地球动力学，构造和热演化。在这方面，关于火星地壳组成的有趣辩论正在进行中。在几个地方存在高度分化的岩石，以及它们对行星的热状态，结构和演化的影响还没有得到很好的理解。在这里，我们系统地探讨了地壳材料特性（特别是导热性和密度）对火星岩石圈的热和机械结构的影响。为此，我们分析了各种条件下岩石圈的热状态、强度和力学行为的不同关键指标。我们这样做，考虑适当的参数，名义上玄武岩火星地壳和端员玄武岩地壳，将包括一个显着的低密度和高导热性的组成部分。我们发现，地壳物质的性质有很强的控制整个岩石圈的热状态，从而在岩石圈地幔的强度。虽然地壳密度较低降低了脆性强度，但由于热导率较高，导致较冷的地温导致较强的地壳和岩石圈地幔，从而导致较厚的岩石圈。由于地壳和地幔的贡献较大，这也导致了岩石圈作为一个整体在总强度和有效弹性厚度方面的增强。另一方面，我们还研究了火星上地幔流变性对岩石圈总强度的影响。含水量对上地幔流变性有很大的影响。湿流变学意味着地幔对岩石圈总强度和有效弹性厚度的贡献大大减少，导致岩石圈整体明显变弱。我们的研究结果将有助于提高我们对InSight和ExoMars任务地球物理观测的理解，并进一步限制理论建模工作。
In depth knowledge of the thermal and rheological properties of the crust and mantle of Mars is fundamental for constraining the strength of its lithosphere, and thereby for the understanding its geodynamics, tectonics, and thermal evolution. In this context, an interesting debate on Martian crustal composition is ongoing. The presence of highly differentiated rocks at several locations, and their implications for the thermal state, structure, and evolution of the planet are not well understood. Here we systematically explore the effects of crust material properties (specifically thermal conductivity and density) on the thermal and mechanical structure of the Martian lithosphere. For this purpose, we analyze different key indicators of the thermal state, the strength and mechanical behavior of the lithosphere under a wide range of conditions. We do so by considering suitable parameters for both a nominally basaltic Martian crust and an end-member basaltic crust that would include a significant low density and high thermal conductivity component. We find that crust material properties have a strong control over the thermal state of the entire lithosphere, and thereby over the strength of the lithospheric mantle. Although a lower crustal density reduces the brittle strength, the colder geotherm due to a higher thermal conductivity leads to a stronger crust and lithospheric mantle, and therefore to a thicker lithosphere. It also leads to a stronger lithosphere as a whole in terms of total strength and effective elastic thickness, as a consequence of higher crust and mantle contributions. On the other hand, we also investigate the influence of the rheology of Mars' upper mantle on the total strength of its lithosphere. Water content has a large effect on the rheology of the upper mantle. A wet rheology implies a substantial reduction of the mantle contribution to the total strength and effective elastic thickness of the lithosphere, resulting in a significantly weaker lithosphere as a whole. Our results will serve both to improve our understanding of geophysical observations from the InSight and ExoMars missions, and to further constrain theoretical modeling efforts.