Understanding magma storage and differentiation in the East African Rift underpins our understanding of volcanism in continental rift settings. Here, we present the geochemistry of melt inclusions erupted in Main Ethiopian Rift transitional basalts, trachytes, and peralkaline rhyolites, produced by fractional crystallization. Basalts stored on‐ and off‐axis are saturated in an exsolved volatile phase at up to 18 km in the upper crust. Much of the CO₂ outgassed from the magmas is likely lost through diffuse degassing. Observed CO₂ fluxes require the intrusion of up to 0.14 km³ of basalt beneath the rift each year. On‐axis peralkaline rhyolites are stored shallowly, at ~4–8 km depth. In the Daly Gap, magmas saturate in sulfide and an exsolved volatile phase, which promotes magma rise to shallower levels in the crust. Here, magmas undergo further protracted fractional crystallization and degassing, leading to the formation of a substantial exsolved volatile phase, which may accumulate in a gas‐rich cap. The exsolved volatile phase is rich in sulfur and halogens: their projected loadings into the atmosphere during explosive peralkaline eruptions in the MER are predicted to be substantially higher than their metaluminous counterparts in other settings. The high fraction of exsolved volatiles in the stored magmas enhances their compressibility and must be considered when interpreting ground displacements thought to be caused by magma intrusion at depth; otherwise, intruding volumes will be underestimated. Pockets of exsolved volatiles may be present at the roof zones of magma reservoirs, which may be resolvable using geophysical techniques.

中文翻译：

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通过埃塞俄比亚主要裂谷的上地壳分布的挥发性丰富的岩浆

了解东非大裂谷的岩浆储存和分化，加深了我们对大陆大裂谷环境中火山作用的理解。在这里，我们介绍了由分步结晶产生的主要埃塞俄比亚裂谷过渡玄武岩，速溶岩和高碱性流纹岩中喷出的熔体包裹体的地球化学。轴上和轴外储存的玄武岩在上地壳中长达18 km的已溶挥发相中饱和。从岩浆脱气的大部分CO ₂可能会通过弥散脱气而损失掉。观察到的CO ₂通量需要侵入达0.14 km ³每年在裂谷之下的玄武岩。同轴的碱性碱性流纹岩浅埋，深度约4-8 km。在Daly Gap中，岩浆在硫化物中饱和，并具有溶解的挥发相，这促使岩浆在地壳中上升到较浅的水平。在这里，岩浆进一步经历了长时间的分级结晶和脱气，导致形成大量溶解的挥发相，这些挥发相可能积聚在富气盖中。溶解的挥发性相富含硫和卤素：在MER中爆炸性碱性碱爆发期间，预计其进入大气的负荷将大大高于其他环境中的含金属的负荷。储存的岩浆中溶解的挥发物含量高，可增强其可压缩性，在解释被认为是由于岩浆侵入深层而引起的地面位移时必须加以考虑；否则，入侵量将被低估。岩浆储集层的顶部区域可能存在溶解的挥发物囊，可以使用地球物理技术将其溶解。