A study of radiogenic (Sr, Nd) and stable (C, O) isotopic data for rare earth carbonatites from the Petyayan-Vara field of the Devonian Vuoriyarvi alkaline-ultrabasic massif is presented. The cumulative evidence indicates that the primary igneous rocks of the Petyayan-Vara area are burbankite-bearing magnesiocarbonatites having isotopic signatures of the depleted mantle (εNd_365Ma = 5.0, ⁸⁷Sr/⁸⁶Sr_(i) = 0.7031, δ¹³C ca. –4‰, and δ¹⁸O ca. 11‰). Interaction of the primary carbonatite melt with the host silicate rocks produced high-Ti carbonatites with a mantle δ¹³C (ca. –4‰) and isotopically heavy δ¹⁸O (ca. 20‰). These rocks trapped K, Na, Mg, CO₂, and rare earth elements (REEs) (mainly heavy REEs) from the melt and Si, Al, Fe, Ti, and P from the host rocks. Early post-magmatic exposure of burbankite-bearing carbonatites to a mixture of fluids of crustal and orthomagmatic carbonatite origin caused redistribution of REEs, Ba, and Sr and formation of REE-rich carbonatites with abundant ancylite mineralization. This effect did not disturb the SmNd system but induced radiogenic Sr accumulation and a change in C and O isotopic composition towards heavier values. Later, but most likely before denudation, the Petyayan-Vara rocks underwent another metasomatic event involving crustal fluids infiltrating through fracture systems. This event triggered formation of bastnäsite-rich carbonatites with fewer REEs at the expense of ancylite-rich carbonatites, and changed all the isotopic systems in the affected rocks. This model successfully accounts for the evolution of all the carbonatite varieties discovered to date in the Petyayan-Vara field.

介绍了泥盆纪 Vuoriyarvi 碱性-超基性地块的 Petyayan-Vara 油田稀土碳酸盐岩的放射成因 (Sr, Nd) 和稳定 (C, O) 同位素数据研究。累积证据表明，Petyayan-Vara 地区的原生火成岩是含钾长石的镁碳酸盐岩，具有耗尽地幔的同位素特征 (εNd _365Ma  = 5.0, ⁸⁷ Sr/ ⁸⁶ Sr _(i)  = 0.7031, δ ¹³ C ca. – 4‰，和 δ ¹⁸ O 约 11‰)。原生碳酸岩熔体与主硅酸盐岩的相互作用产生了具有地幔 δ ¹³ C (ca. –4‰) 和同位素重 δ ^{18 的}高钛碳酸岩O（约 20‰）。这些岩石从熔体中捕获 K、Na、Mg、CO ₂和稀土元素 (REE)（主要是重 REE），从母岩中捕获Si、Al、Fe、Ti 和 P。含伯班克石的碳酸岩早期岩浆后暴露于地壳和正岩浆碳酸岩成因的流体混合物中，导致 REE、Ba 和 Sr 的重新分布，并形成富含 REE 的碳酸岩，并具有丰富的斜纹岩矿化。这个效果并没有打扰到 SmNd 系统但诱导放射性 Sr 积累和 C 和 O 同位素组成向更重值的变化。后来，但很可能在剥蚀之前，Petyayan-Vara 岩石经历了另一次交代事件，涉及地壳流体通过裂缝系统渗透。这一事件引发了富含氟碳铈矿的碳酸盐岩的形成，而 REE 较少，而牺牲了富含锡石的碳酸盐岩，并改变了受影响岩石中的所有同位素系统。该模型成功地解释了迄今为止在 Petyayan-Vara 油田发现的所有碳酸岩品种的演化。