Pyroxenite and nepheline-pyroxene rocks coexist with dolomite-bearing calcite marbles in Tazheran Massif in the area of Lake Baikal, Siberia, Russia. Pyroxenites occur in a continuous elongate zone between marbles and beerbachites (metamorphosed gabbro dolerites) and in 5 cm to 20 m fragments among the marbles. Pyroxene in pyroxenite is rich in calcium and alumina (5–12 wt% Al₂O₃) and has a fassaite composition. The Tazheran pyroxenite may originate from a mafic subvolcanic source indicated by the presence of remnant dolerite found in one pyroxenite body. This origin can be explained in terms of interaction between mafic and crust-derived carbonatitic melts, judging by the mineralogy of pyroxenite bodies and their geological relations with marbles. According to this model, the intrusion of mantle mafic melts into thick lower crust saturated with fluids caused partial melting of silicate-carbonate material and produced carbonate and carbonate-silicate melts. The fassaite-bearing pyroxenite crystallized from a silicate-carbonate melt mixture which was produced by roughly synchronous injections of mafic, pyroxenitic, and carbonate melt batches. The ascending hydrous carbonate melts entrained fragments of pyroxenite that crystallized previously at a temperature exceeding the crystallization point of carbonates. Subsequently, while the whole magmatic system was cooling down, pyroxenite became metasomatized by circulating fluids, which led to the formation of assemblages with garnet, melilite, and scapolite.

中文翻译：

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辉石作为镁铁质-碳酸盐熔体相互作用的产物（俄罗斯西贝加尔湖地区的 Tazheran 地块）

在俄罗斯西伯利亚贝加尔湖地区的 Tazheran 地块，辉石岩和霞石辉石岩与含白云石的方解石大理岩共存。辉石岩出现在大理石和贝尔巴赫石（变质辉长岩）之间的连续细长带中，并且出现在大理石之间 5 cm 至 20 m 的碎片中。辉石中的辉石富含钙和氧化铝（5–12 wt% Al ₂ O ₃) 并具有法赛组成。Tazheran辉石岩可能起源于一个镁铁质亚火山源，这表明在一个辉石岩体中发现了残余辉绿岩。根据辉石岩体的矿物学及其与大理石的地质关系，可以根据镁铁质和地壳衍生的碳酸岩熔体之间的相互作用来解释这一起源。根据该模型，地幔基性熔体侵入充满流体的厚下地壳，导致硅酸盐-碳酸盐物质部分熔融，产生碳酸盐和碳酸盐-硅酸盐熔体。含钙镁辉石的辉石是从硅酸盐-碳酸盐熔体混合物中结晶出来的，该熔体混合物是通过大致同步注入镁铁质、辉石岩和碳酸盐熔体批次生产的。上升的含水碳酸盐熔化夹带的辉石岩碎片，这些碎片先前在超过碳酸盐结晶点的温度下结晶。随后，在整个岩浆系统冷却的同时，辉石岩被循环流体交代，形成了石榴石、黄长石和方长石的组合。