Jurnal Internasional Pencampuran dan pembersihan kristal dalam Rift Ethiopian Utama yang diungkap oleh sistematika elemen dalam feldspars dan kacamata – Iddon – Geokimia, Geofisika, Geosystems
For many magmatic systems, the composition of the crystals preserves complex and protracted history which may be largely separated from the melting of their carriers. The crystalline cargo may have clues to the physical distribution of melts and crystals in the magma reservoir and how the magma was assembled before the eruption. Here we present a geochemical study of a series of samples from three peralkaline volcanoes in the Ethiopian Rift Main. While whole-rock data shows signs of strong fractional crystallization, systematics of trace elements feldspar, and their relationship to their host's glasses, reveal complexity. Alkaline feldspars, especially those that erupt during episodes of caldera formation, have varying Ba concentrations, extending to high values that are not balanced with the carrier fluid. Some feldspars are antecrysts, what we recommend is scavenging from crystal-rich pulp. Antecrysts crystallize from Ba-more enriched (more primitive) liquefaction, before then entrainment becomes the residual liquid of Ba-out. Segregation melt crystals can occur on a fast time scale in this magma reservoir, due to the low viscosity properties of peralkalin fluids. Sufficient residual melting separation to feed the rhyolitic eruption of crystalline-poor post-caldera may take only a few months to decades (much shorter than the typical resting period of 300-400 years). Our observations are consistent with this magmatic system which consumes significant parts of their life cycle which are dominated by crystalline matter containing ephemeral, small (3) melt segregation. This interpretation helps to reconcile the observations of high scale electrical resistivity below Aluto, although seismicity and soil deformation are consistent with the body of the magma.