Magma Evolution and Plumbing System OF Gede Salak Volcano, Banten, Indonesia
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Date
2023-07-14
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Abstract
The study of volcanoes in northwest Java has been largely overlooked. In this study,
an investigation of the magma evolution and plumbing system of the Gede Salak
volcano in the area was conducted. A geological survey determined the lava unit
and volcanism. Whole-rock geochemistry is utilized to determine magma type and
evolution. Mineral chemistry analysis revealed the magmatic process and
phenocrysts` origin. Geothermobarometry is employed to estimate temperature and
pressure. The volcanism comprised the eruption of lava flows, sector collapse, and
the eruption of lava domes. The magma evolution consists of type A (lava flow and
peripheral dome) and type B (summit dome). The processes identified are
amphibole fractionation, magma mixing, and crust assimilation. Phenocryst
textures and chemistry implied open-system processes in the plumbing system
involving three magma series: the felsic, intermediate, and mafic. Magma type A
resulted from multiple mafic recharges on the felsic series, while type B resulted
from the mixing of intermediate and mafic series. The felsic and intermediate
phenocryst crystallization occurred at 933–948°C and 1010–1011°C in the midcrust at 14 km to 17 km depth. Meanwhile, the mafic series reside in the lower crust
at 21 km depth and 1065–1087°C temperature.
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Keywords
Gede Salak volcano, Magma evolution, Magma plumbing