Abstract Metamorphic petrology observations on rubies found in-situ in their host-rock are combined with geochemical measurements and optical microscopy observations on the same rubies, with the aim of connecting the ruby-forming metamorphic reaction to a unique fingerprint for these minerals. The Fiskenaesset complex in Greenland is used as an area of this case study. Isochemical pressure-temperature sections were calculated based on electron microprobe and whole-rock geochemistry analyses, and compared to field observations. Rubies formed from reaction between olivine/serpentine and anorthite, triggered by the intrusion of a 2.71 Ga pegmatite. Al is sourced from the anorthite reacting to calcic amphibole, silica from the pegmatite reacts with olivine/serpentine to anthophyllite, Cr3+ is mobile in the pegmatitic fluid, giving colour to the rubies. The ruby-forming reaction occurs at about 640 °C and 7 kbar. In order to establish the unique fingerprint for this ruby-bearing ultramafic complex, laser-ablation inductively-coupled-plasma mass-spectrometry trace-element measurements, oxygen isotope compositions, optical microscopy and scanning electron microscopy were applied. Due to the setting in an ultramafic rock-anorthosite-leucogabbro complex, the fingerprint of the rubies from the Fiskenaesset complex is rather unique. Compared to rubies from other localities, Fiskenaesset complex rubies contain high Cr, intermediate Fe, and low V, Ga, and Ti concentrations, low oxygen isotope values (1.6–4.2‰) and a rarely-observed combination of optical growth features and mineral inclusions like anthophyllite+biotite. Results for other Greenland localities are presented and discussed as well. Even though these are derived from ultramafic rock settings too, they record different trace-element ratios and oxygen isotope values, resulting from variations in the Archaean ruby-forming reaction.

中文翻译：

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格陵兰 Fiskenæsset 复合体的刚玉（红宝石和粉红蓝宝石）的形成、起源和地理分类

摘要 将原位红宝石的变质岩石学观察与相同红宝石的地球化学测量和光学显微镜观察相结合，目的是将形成红宝石的变质反应与这些矿物的独特指纹联系起来。格陵兰的 Fiskenaesset 综合体被用作本案例研究的一个领域。基于电子微探针和全岩地球化学分析计算等化学压力-温度剖面，并与现场观测进行比较。红宝石由橄榄石/蛇纹石和钙长石之间的反应形成，由 2.71 Ga 伟晶岩的侵入引发。铝来自钙长石与钙闪石反应，伟晶岩中的二氧化硅与橄榄石/蛇纹石反应为直闪石，Cr3+ 在伟晶岩流体中移动，使红宝石有颜色。红宝石形成反应在约 640 °C 和 7 kbar 下发生。为了为这种含红宝石的超镁铁质复合物建立独特的指纹，应用了激光烧蚀电感耦合等离子体质谱微量元素测量、氧同位素组成、光学显微镜和扫描电子显微镜。由于位于超镁铁质岩石-斜长岩-白光长岩复合体中，来自 Fiskenaesset 复合体的红宝石的指纹相当独特。与其他产地的红宝石相比，Fiskenaesset 复合红宝石含有高 Cr、中等 Fe 和低 V、Ga 和 Ti 浓度、低氧同位素值 (1.6–4.2‰) 以及很少观察到的光学生长特征和矿物包裹体的组合像直闪石+黑云母。还介绍和讨论了其他格陵兰地区的结果。