Titanium-rich basaltic melts on the Moon modulated by reactive flow processes
Titanium-rich basaltic melts on the Moon modulated by reactive flow processes
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DOI：
10.1038/s41561-023-01362-5
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发表时间：
2024-01
影响因子：
18.3
通讯作者：
M. Klaver;S. Klemme;Xiao-Ning Liu;R. Hin;C. Coath;M. Anand;C. Lissenberg;J. Berndt;Tim Elliott
中科院分区：
文献类型：
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作者：
M. Klaver;S. Klemme;Xiao-Ning Liu;R. Hin;C. Coath;M. Anand;C. Lissenberg;J. Berndt;Tim Elliott
月球上富含钛的玄武岩浆的起源仍然是个谜。月球地幔中含有钛铁矿的堆积物通常被认为是来源，但它们的部分熔融物的成分不匹配，而且密度太大，无法喷发。在这里，我们使用岩石学的反应实验表明，部分熔体的钛铁矿轴承堆与橄榄石和斜方辉石在月球地幔反应，转移熔体组合物的高钛套件。新的高精度镁同位素数据证实，高钛玄武岩具有变量和同位素轻镁同位素组成，不符合平衡部分熔融。我们采用扩散模型来证明，动力学同位素分馏反应流的部分熔体来自含钛铁矿堆积可以解释这些令人不安的轻镁同位素组成，以及其他元素，如铁，钙和钛的同位素组成。虽然这个模型并不完全复制月球熔体-固体相互作用，我们认为，富钛岩浆爆发在月球表面上可以通过部分熔融的钛铁矿轴承累积，但熔体进行广泛的修改，其元素和同位素组成，通过反应流在月球地幔。因此，反应流可能是降低熔体密度并允许高钛熔体在月球表面喷发的关键过程。
The origin of titanium-rich basaltic magmatism on the Moon remains enigmatic. Ilmenite-bearing cumulates in the lunar mantle are often credited as the source, but their partial melts are not a compositional match and are too dense to enable eruption. Here we use petrological reaction experiments to show that partial melts of ilmenite-bearing cumulates react with olivine and orthopyroxene in the lunar mantle, shifting the melt composition to that of the high-Ti suite. New high-precision Mg isotope data confirm that high-Ti basalts have variable and isotopically light Mg isotope compositions that are inconsistent with equilibrium partial melting. We employ a diffusion model to demonstrate that kinetic isotope fractionation during reactive flow of partial melts derived from ilmenite-bearing cumulates can explain these anomalously light Mg isotope compositions, as well as the isotope composition of other elements such as Fe, Ca and Ti. Although this model does not fully replicate lunar melt–solid interaction, we suggest that titanium-rich magmas erupted on the surface of the Moon can be derived through partial melting of ilmenite-bearing cumulates, but melts undergo extensive modification of their elemental and isotopic composition through reactive flow in the lunar mantle. Reactive flow may therefore be the critical process that decreases melt density and allows high-Ti melts to erupt on the lunar surface.