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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 >Origin of lunar high-titanium ultramafic glasses: A hybridized source?
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Origin of lunar high-titanium ultramafic glasses: A hybridized source?

机译：月球高钛超镁铁玻璃的起源：杂种？

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Two new hypotheses for the origin of the lunar high-Ti ultramafic glasses are considered in this study. These new models are motivated by experimental results on a model hybridized lunar magma ocean cumulate composition and by the failure of current models to adequately account for the processes that lead to the origin of these unique lunar ultramafic magmas. In the first model we propose that the observed compositional variability at the high-Ti end of the glass spectrum is created by melting of compositionally heterogeneous source materials produced during the late stages of magma ocean crystallization. The lunar hybridized source composition that we have investigated can broadly reproduce the major element compositional characteristics of the Apollo 17 orange glass and is saturated with olivine and orthopyroxene as residual phases in the source. Models of higb-Ti glass generation that include fractional crystallization and/or melting involving olivine and orthopyroxene are attractive because all lunar ultramafic melts show evidence of high-pressure multiple saturation with these phases. Crystallization of olivine and orthopyroxene in the proportions indicated from high-pressure experimental results however, will not produce the entire spectrum of high-Ti glasses. Perhaps the compositional variability is caused by heterogeneity in the proportions of phases stored as late stage cumulate residues. In the second model, low-degree partial melts of the hybridized magma ocean source are segregated during partial melting and sink into and interact with underlying hotter olivine+orthopyroxene cumulates by reactive porous flow, giving rise to the compositional spectrum observed in the high-Ti ultramafic glasses. In this model, the Apollo 17 high-Ti orange glass is produced by the highest degree of melting of the hybridized source. Higher-Ti ultramafic glasses (e.g. Apollo 15 red and Apollo 14 black glasses) are produced by smaller degrees of melting of the hybridized source when olivine+orthopyroxene+clinopyroxene are still present as saturating phases. In this model, the depth of segregation of the high-Ti ultramafic magma is determined by the change in buoyancy brought about by the reactive dissolution of olivine+orthopyroxene cumulates. As the high-Ti melt dissolved these phases, its density decreases, until it becomes neutrally or positively buoyant. (C) 2008 Elsevier B.V. All rights reserved.
机译：在这项研究中考虑了两个有关月球高钛超镁铁玻璃起源的新假设。这些新模型的动力来自混合月球岩浆海洋累积成分模型的实验结果，以及当前模型未能充分考虑导致这些独特的月球超镁铁质岩浆起源的过程。在第一个模型中，我们建议在玻璃光谱的高Ti端观察到的成分变异性是由岩浆海洋结晶后期产生的成分异质原料融化产生的。我们研究的月球杂化源组成可以广泛再现Apollo 17橙色玻璃的主要元素组成特征，并且在源中被橄榄石和邻二甲苯饱和作为残余相。由于所有月球超镁铁质熔体均显示出在这些相中出现高压多重饱和的证据，因此包括梯度结晶和/或涉及橄榄石和邻二甲苯的熔融的higb-Ti玻璃生成模型具有吸引力。然而，按照高压实验结果表明的比例，橄榄石和邻苯二酚的结晶不会产生高钛玻璃的整个光谱。可能是由于后期累积的残基存储的相的比例异质性造成了组成变异性。在第二个模型中，杂交岩浆海洋源的低度部分熔融在部分熔融期间被隔离，并通过反应性多孔流沉入下面的较热的橄榄石+邻二甲苯并与之相互作用，从而产生了在高钛中观察到的组成光谱超镁铁眼镜。在此模型中，Apollo 17高钛橙色玻璃是由混合源的最高熔融度制成的。当仍然存在橄榄石+邻苯二甲酚+ Clinopyroxene作为饱和相时，杂化源的熔化程度较小，可以生产出高Ti超镁铁玻璃（例如Apollo 15红色和Apollo 14黑色玻璃）。在该模型中，高钛超镁铁质岩浆的偏析深度由橄榄石+邻二甲苯累积物的反应性溶解所引起的浮力变化决定。当高钛熔体溶解这些相时，其密度降低，直到变为中性或正浮力。 （C）2008 Elsevier B.V.保留所有权利。

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