We constrained the solidus of a model Martian composition with low bulk Mg# (molar MgO/(MgO + FeO_T) × 100 ~75) and high total alkali (Na₂O + K₂O = 1.09 wt.%) concentration at 2 to 5 GPa by experiments. Based on the new solidus brackets, we provide a new parameterization of the solidus temperature as a function of pressure of Martian mantle: T_s(°C) = − 5P (GPa)² + 107P(GPa) + 1,068. The newly constrained solidus of the Lodders and Fegley (1997; https://doi.org/10.1006/icar.1996.5653) model Martian composition (LF composition) is 20 to 90 °C lower than the previous solidus of model Martian mantle with lower total alkali (~0.54 wt.%). The supersolidus experiments yield an average isobaric melt productivity, dF/dT, of 20 ± 6 wt.%/100 °C. We also bracketed the solidi of model Martian mantle compositions with low Mg# (~75) and low alkali (~0.54 wt.%), and with high Mg# (~80) and low alkali (~0.54 wt.%) at a constant pressure of 3 GPa. We find that bulk Mg# enhances the solidus temperature and bulk total alkalis suppress it. A parameterization that estimates the effect of bulk Mg# and total alkalis on peridotite solidus, including Mars and Earth, at 3 GPa can be described as: T_s(°C) = 4.23Mg # − 85(Na₂O(wt. %) + K₂O(wt. %)) + 1,120. Based on the new solidus parameterizations, 10–40 km more Martian crust would be produced by columnar decompression melting for LF model composition compared to the low Mg#‐low alkali model composition. The quantitative constraints on the solidus shift with Mg# and total alkalis from this study can be used to assess the Martian mantle solidus change through melting and melt extraction over time and the role of mantle heterogeneity in crustal production.

中文翻译：

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新的高压-高温实验限制了名义无水火星地幔的固相和熔体生产力-对地壳生产和地幔源演化的影响

我们限制了模型火星组成的固相线，其在2时的Mg＃低（摩尔MgO /（MgO + FeO _T）×100〜75）和高的总碱浓度（Na ₂ O + K ₂ O = 1.09 wt。％）通过实验达到5 GPa。基于新的固相线托架，我们提供了新的固相线温度参数化参数，该参数是火星地幔压力的函数：T _s（° C）= − 5 P  （GPa）²  + 107 P（GPa）+ 1,068。Lodders and Fegley（1997; https://doi.org/10.1006/icar.1996.5653）的新约束固相线比之前的模型火星地幔固相线低20至90°C总碱（〜0.54重量％）。超固相线实验得出平均等压熔体生产率d F / d T，为20±6 wt。％/ 100°C。我们也将Mg＃（〜75）和低碱（〜0.54 wt。％）以及Mg＃（〜80）和低碱（〜0.54 wt。％）的模型火星地幔组合物的固相线括起来恒定压力为3 GPa。我们发现，大量的Mg＃会提高固相线温度，而大量的总碱会抑制固相线温度。以3 GPa估算块状Mg＃和总碱对橄榄岩固相线（包括火星和地球）的影响的参数化可以描述为：T _s（°C）= 4.23Mg＃-85（Na ₂ O（wt。％） ）+ K ₂ O（wt。％））+ 1,120。根据新的固相线参数化，与低Mg＃-低碱模型组成相比，LF模型组成的柱状减压熔融将产生10-40 km以上的火星地壳。这项研究对Mg＃和总碱对固相线移动的定量限制可用于评估火星地幔固线随时间的融化和熔体提取变化以及地幔非均质性在地壳生产中的作用。