The Lovozero Alkaline Massif intruded through the Archean granite-gneiss and Devonian volcaniclastic rocks ca. 360 Ma ago and formed a large laccolith-type body. The lower part of the massif (the Layered complex) is composed of regularly repeating rhythms: melanocratic nepheline syenite (lujavrite, at the top), leucocratic nepheline syenite (foyaite), foidolite (urtite). The upper part of the massif (the Eudialyte complex) is indistinctly layered, and lujavrite enriched with eudialyte-group minerals (EGM) prevails there. In this article, we present the results of a study of the chemical composition and petrography of more than 400 samples of the EGM from the main types of rock of the Lovozero massif. In all types of rock, the EGM form at the late magmatic stage later than alkaline clinopyroxenes and amphiboles or simultaneously with it. When the crystallization of pyroxenes and EGM is simultaneous, the content of ferrous iron in the EGM composition increases. The Mn/Fe ratio in the EGM increases during fractional crystallization from lujavrite to foyaite and urtite. The same process leads to an increase in the modal content of EGM in the foyaite of the Layered complex and to the appearance of primary minerals of the lovozerite group in the foyaite of the Eudialyte complex.

中文翻译：

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Eudialyte Group来自俄罗斯Lovozero碱性地块的矿物：发生，垂直组合和岩石成因意义

Lovozero碱性地块穿过太古宙花岗岩-片麻岩和泥盆纪火山碎屑岩侵入。360 Ma以前，形成了大型的漆器型主体。地块的下部（层状复合体）由规律重复的节律组成：黑克拉通霞石正长岩（顶部为lujavrite），白垩系霞石正长岩（方沸石），泡沫岩（辉石）。地块的上半部分（尤迪亚岩复合体）不清楚地分层，富含富勒迪亚岩类矿物（EGM）的黄榴石在那里盛行。在本文中，我们介绍了对Lovozero地块主要岩石中的400多个EGM样品进行化学成分和岩石学研究的结果。在所有类型的岩石中，EGM在岩浆晚期形成的时间都晚于碱性斜ino和闪石或同时发生的时间。当辉石和EGM的结晶同时进行时，EGM组合物中亚铁的含量增加。EGM中的Mn / Fe比在从黄铁矿到foyaite和urtite的分步结晶过程中增加。相同的过程导致层状复合体的沸石中EGM的模态含量增加，以及Eudialyte复合体的沸石中的钙锌矿基矿物的出现。