Compositional variability of San Carlos olivine
Compositional variability of San Carlos olivine
复制标题
圣卡洛斯橄榄石的成分变化
DOI：
10.1016/j.chemgeo.2022.120968
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发表时间：
2022
期刊：
影响因子：
3.9
通讯作者：
Lang, Otto I.
中科院分区：
文献类型：
--
作者：
Lambart, Sarah;Hamilton, Sarah;Lang, Otto I.
来自San Carlos （Arizona, SW USA）的富磷橄榄石组成物通常被用作实验岩石学的起始材料。与圣卡洛斯参考物质USNM 111312/444相比，表明非USNM圣卡洛斯橄榄石的主要元素变异是显著的。我们用新数据补充了非usnm圣卡洛斯橄榄石的成分变异性特征，包括微量元素和微量元素分析。高精度分析表明，微量元素（NiO ~6%, MnO ~10%, CaO ~16%，相对含量）和微量元素（Cr ~75%, Cu ~120%, P ~160%， Ti相对含量）在颗粒间存在显著差异。然而，在单个颗粒的尺度上，富含圣卡洛斯福的橄榄石似乎是均匀的，没有系统的核心-边缘变化。本文还讨论了与橄榄岩包体相关的橄榄石辉石岩的成因，认为它们是由橄榄岩宿主的橄榄石溶蚀和辉石沉淀引起的熔岩反应产生的。杂化残熔体进一步偏析和原位结晶可生成富铁贫橄榄石辉石岩。最后，我们讨论了圣卡洛斯地幔橄榄石中P变化的来源，并提出交代富集P意味着一个快速溶解-再沉淀固相的高度反应过程。
Forsterite (Fo)-rich olivine compositions from San Carlos (Arizona, SW USA) are commonly used as starting material in experimental petrology. In comparison to the San Carlos reference material USNM 111312/444, it has been shown that the major element variability of non-USNM San Carlos olivine is significant. We complement the characterization of the compositional variability of the non-USNM San Carlos olivine with new data, including minor and trace element analyses. High precision analyses reveal that selected minor elements (e.g., ~6% NiO, ~10% MnO, ~16% CaO, relative) and trace elements (e.g., ~75% Cr, ~120% Cu, ~160% P and Ti, relative) present significant concentration variations between grains. At the scale of the individual grain, however, San Carlos Fo-rich olivines appear homogeneous with no systematic core-rim variations. We also discuss the origin of olivine pyroxenites associated with the peridotite xenoliths and argue that they are derived by melt-rock reaction resulting in olivine dissolution and pyroxene precipitation from the peridotite host. Further segregation and in situ crystallization of the hybrid residual melt can produce Fe-rich olivine-poor pyroxenites. Finally, we discuss the origin of the P variability in San Carlos mantle olivine and suggest that P enrichment by metasomatism implies a highly reactive process with fast dissolution-reprecipitation of solid phases.