Berlo, K. | DOOR - DOuglas Open Repository

Berlo, K.

Person Preferred Name

K. Berlo

Related Works

Sulfide breakdown controls metal signature in volcanic gas at Kawah Ijen volcano, Indonesia

Digital Document

Immiscible sulfide liquid is thought to be an important intermediary in volcanic degassing of sulfur and chalcophile elements by concentrating and transferring metals from magma to hydrous fluid. Here, we track the interaction of sulfide liquid with a fluid exsolving from basalt at Kawah Ijen volcano in Indonesia. As in many other volcanic systems, neither sulfide nor fluid is preserved. Instead, the reaction is recorded in changes in metal and sulfur concentrations in the melt during magma ascent, and shows a two-stage evolution; deep-seated progressive breakdown of sulfide during which metal concentrations in the melt are largely controlled by the sulfide, followed by fluid–melt partitioning controlling metal concentrations at shallow depth once this sulfide has been exhausted. Present-day fumarole gases have similar Zn/Cu, Pb/Cu and Mo/Cu ratios to the reconstructed sulfide, but are enriched in Tl, As and Sb. These enrichments are also observed in melt inclusions in the most recent dacitic deposits at Kawah Ijen. This suggests that the fumarole gases are sourced from a deep, degassing sulfide-saturated basalt, preserved in Zn/Cu, Pb/Cu and Mo/Cu ratios, which subsequently interact with a shallow dacitic melt that enhances Tl, As and Sb emissions.

Integrated geochemical modeling of magmatic degassing and hydrothermal interaction at Kaway Ijen volcano, Indonesia

Digital Document

Poster presentation at the <a href="http://www.iugg.org/">International Union of Geodesy and Geophysics (IUGG)</a> conference, Montreal, Canada (July 8-18, 2019). <p>Monitoring active volcanoes requires an understanding of magmatic degassing in relation to magma depth, temperature, composition, style of degassing (open vs closed) and interactions with hydrothermal systems. This conference presentation combines results of subsurface degassing (interpreted from melt inclusions) with measurements of fumarole gases and acid spring waters from Kawah Ijen volcano, Indonesia. Kawah Ijen is a stratovolcano with a growing rhyolite dome on the shore of a hyperacidic crater lake. The dome is emitting sulfur-rich gases from high temperature fumaroles (350-450°C). Matrix glass and melt inclusion compositions (including H2O, CO2, S, Cl and F) were measured for basaltic, dacitic and rhyolitic magmas. The behavior of the volatile species (Dvap-melt) during ascent, degassing and crystallization were modeled for an open system (including vapor fluxing) assuming Rayleigh fractionation, and for closed system processes assuming batch degassing and crystallization. The variable H2O-CO2 contents of the melt inclusions suggest that open system vapor fluxing (XH2Ovapor = 0.25-0.95 for basalt; 0.9-0.95 for dacite) is the dominant degassing style. The modeled S Dvap-melt values for basalt remain low (2-10) as the melt ascends (P= 400 to 100 MPa), then increase sharply to 200 at pressures.</p>

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