Pre- and syn-eruptive degassing and crystallisation processes of the 2010 and 2006 eruptions of Merapi volcano, Indonesia

• DOI: 10.1007/s00410-014-1061-z
• Publication Date: 2014-09-30T05:29:49Z
• Authors: Katie Preece; Ralf Gertisser; Jenni Barclay; Kim Berlo; Richard A. Herd
• Keywords: Mineral resource classification

The 2010 eruption of Merapi (VEI 4) was the volcano's largest since 1872. In contrast to prolonged and effusive dome-forming eruptions typical Merapi's recent activity, began explosively, before a new dome rapidly emplaced. This subsequently destroyed by explosions, generating pyroclastic density currents (PDCs), predominantly consisting dark coloured, dense blocks basaltic andesite lava. A shift towards open-vent conditions in later stages culminated multiple explosions generation PDCs with conspicuous grey scoria white pumice clasts resulting from sub-plinian convective column collapse. paper presents geochemical data for melt inclusions their clinopyroxene hosts extracted lava, generated during peak eruption. These are compared clinopyroxene-hosted scoriaceous fragments 2006 eruption, elucidate any relationship between pre-eruptive degassing crystallisation processes eruptive style. Secondary ion mass spectrometry analysis volatiles (H2O, CO2) light lithophile elements (Li, B, Be) is augmented electron microprobe major (Cl, S, F) groundmass glass. Geobarometric shows that phenocrysts crystallised at depths up 20 km, greatest calculated associated pumice. Based on volatile contents, have re-equilibrated shallower storage and/or ascent, ~0.6–9.7 where magma system interpreted be highly interconnected not formed discrete reservoirs. Melt enriched Li show uniform "buffered" Cl concentrations, indicating presence an exsolved brine phase. Boron-enriched also support phase, which helped stabilise B melt. Calculations based S concentrations glass require volume 0.36 km3 order produce SO2 emitted approximately magnitude higher than erupted (DRE) volume. transition contrasting styles linked changes magmatic flux style, explosive activity driven influx deep magma, overwhelmed ascended rapidly, accompanied closed-system degassing.