The leucite basanites of the Visoke and Muhavura volcanoes from the province of Virunga (Western Branch of the East African Rift) were investigated in detail. The major and trace element contents and Sr, Nd and Pb isotopic composition in the whole rocks were determined. The isotope ratios (⁸⁷Sr/⁸⁶Sr: 0.70644–0.70793; ¹⁴³Nd/¹⁴⁴Nd: 0.51233–0.51243) show that these rocks are far from the bulk Earth on the “mantle trend” and enriched in radiogenic Sr. The major element compositions reveal that they are not primary mantle melts as they have Mg# = 0.50–0.59. Moreover the leucite basanites are enriched by LILE and LREE relative to PM which may indicate an enriched mantle source. Pb isotopes of the studied leucite basanites (²⁰⁶Pb/²⁰⁴Pb: 19.112–19.438, ²⁰⁷Pb/²⁰⁴Pb: 15.737–15.783, ²⁰⁸Pb/²⁰⁴Pb: 40.509–40.866) along with the data of Karisimbi volcano form trends on isotope diagrams towards the EM II or ancient continental crust. The position of leucite basanite data on the ⁸⁷Sr/⁸⁶Sr - ²⁰⁸Pb*/²⁰⁶Pb* correlation line suggests that they can be a result of melt enrichment/vein metasomatism within the mantle.

The phenocryst composition of leucite basanites varies in range: olivine- from Fo₅₅ to Fo₈₉ with NiO content 0.01–0.34% wt.; clinopyroxene - from 0.65 up to 0.86 Mg# with Cr₂O₃ from 0.02 to 1.5% wt., plagioclase corresponds to labradorite (50–70% An). The ore minerals present are titanomagnetite and ilmenite. The evaluation of T-fO₂ based on titanomagnetite and ilmenite composition shows that phenocryst crystallization took place under QFM buffer. The presence of quartz and rutile xenocrysts in one Visoke leucite basanite lava points to the contamination of this melt by crustal material. At the same time, nonequilibrium megacrysts of high-magnesian olivine (Fo₈₉) from another sample of Visoke leucite basanite resulted from leucite-basanite magma mixing with a more primitive melt.

We identify melts from two different sources at Visoke edifice: ugandite and its possible derivatives were formed from the mantle source, whereas the leucite basanites are enriched in radiogenic strontium and could be contaminated by deep metamorphic rocks. The origin of the studied leucite basanites is the result of a combination of various processes: melting of the metasomatized mantle, fractional crystallization, magma mixing and crustal contamination.

详细研究了维龙加省（东非大裂谷的西部分支）的维索克火山和穆哈武拉火山火山岩的白云岩。测定了整个岩石中的主要和微量元素含量以及Sr，Nd和Pb同位素组成。同位素比（⁸⁷ Sr / ⁸⁶ Sr：0.70644–0.70793；¹⁴³ Nd / ¹⁴⁴ Nd：0.51233–0.51243）表明，这些岩石在“地幔趋势”上远离大块地球，并富含放射成因的Sr。主要元素组成揭示它们不是主要的地幔熔体，因为它们的Mg＃= 0.50–0.59。此外，相对于PM，白云石玄武岩富含LILE和LREE，这可能表明地幔来源丰富。研究的白云母玄武岩的Pb同位素（²⁰⁶铅/ ²⁰⁴的Pb：19.112-19.438，²⁰⁷的Pb / ²⁰⁴的Pb：15.737-15.783，²⁰⁸的Pb / ²⁰⁴的Pb：40.509-40.866）同卡里辛比火山形式趋势对朝向EM II或古大陆地壳同位素图中的数据一起。在⁸⁷ Sr / ⁸⁶ Sr- ²⁰⁸ Pb * / ²⁰⁶ Pb *相关线上的白云母玄武岩数据位置表明，它们可能是地幔中熔体富集/静脉交代作用的结果。

白云母basanites的phenocryst组成范围变化：橄榄石-从Fo ₅₅到Fo ₈₉，NiO含量为0.01-0.34％wt .；斜辉石-从0.65到0.86 Mg＃，Cr ₂ O ₃从0.02到1.5％wt。，斜长石相当于拉长石（50-70％An）。存在的矿石矿物是钛磁铁矿和钛铁矿。基于钛磁铁矿和钛铁矿组成的T-fO ₂评估表明，在QFM缓冲液下发生了晶晶结晶。Visoke的白云母Basanite熔岩中存在石英和金红石异晶，这表明该熔体被地壳材料污染。同时，高镁橄榄石的非平衡巨晶（Fo ₈₉）来自另一个Visoke的白云母Basanite样品，其由白云母-玄武岩岩浆与更原始的熔体混合而成。

我们从Visoke大厦的两个不同来源识别出熔体：褐铁矿及其可能的衍生物是从地幔源形成的，而白云母玄武岩中富含放射性锶，并可能被深部变质岩污染。研究的白云母玄武岩的起源是多种过程结合的结果：交代地幔的融化，部分结晶，岩浆混合和地壳污染。