Geochemical analysis of magmas erupted in continental rifts are a valuable tool for understanding the compositional, physical, and thermal controls on rift related magmatism. Bulk rock geochemistry and geochronology of lavas from volcanic fields in the Western Rift of the East African Rift System provide insight into the sources and processes of petrogenesis of magmas in the region, as well as insight into the spatial variability of metasomatic history of the lithospheric mantle. Lava compositions from three primitive volcanic fields in southwestern Uganda (Bufumbira, Virunga Volcanic Province; Katwe-Kikorongo and Bunyaruguru, Toro Ankole Volcanic Province) are potassic (K₂O/Na₂O = 0.3–2.7) and enriched in incompatible trace elements (e.g., (La/Yb)_n = 12–132); the Toro Ankole samples are also silica-undersaturated. The compositions of these lavas require significant input from metasomatized sub-continental lithospheric mantle (SCLM), likely consisting of a pyroxenite containing variable amounts of garnet, amphibole, phlogopite, and accessory minerals including titanite, apatite, and zircon, produced through infiltration by spatially varying carbonatitic and silicate metasomatic agents. A subset of lavas record ⁴⁰Ar/³⁹Ar ages = 21–662 ka, with minor geographic and compositional trends apparent in the temporal development of the volcanic fields.

大陆裂谷喷出的岩浆的地球化学分析是了解裂谷相关岩浆作用的成分，物理和热控制的有价值的工具。东非大裂谷西裂谷火山岩的块状岩石地球化学和年代学提供了对该地区岩浆岩石成因的来源和过程的认识，以及对岩石圈地幔交代史空间变异的认识。 。乌干达西南部三个原始火山场（维丰加火山省的Bufumbira；托罗安科莱火山省的Katwe-Kikorongo和Bunyaruguru）的熔岩成分是钾质的（K ₂ O / Na ₂ O = 0.3-2.7）（富含不相容的痕量元素（例如，（La / Yb）_n = 12–132）; Toro Ankole样品也是二氧化硅不饱和的。这些熔岩的成分需要经过交代的次大陆岩石圈地幔（SCLM）的大量投入，其中可能包括含有不同数量的石榴石，闪石，金云母和辅助矿物（包括钛矿，磷灰石和锆石）的辉石矿，这些矿物质是通过空间渗透作用而产生的。各种碳酸盐和硅酸盐交代剂。一部分熔岩记录了⁴⁰ Ar / ³⁹ Ar年龄= 21–662 ka，在火山场的时空发展中有较小的地理和成分趋势。