Fractionation of families of major, minor, and trace metals across the melt-vapor interface in volcanic exhalations

doi:10.1016/0016-7037(94)90053-1

Geochimica et Cosmochimica Acta

Volume 58, Issue 15, August 1994, Pages 3255-3263

https://doi.org/10.1016/0016-7037(94)90053-1 Get rights and content

Abstract

Chemical families of metals fractionate systematically as they pass from a silicate melt across the interface with the vapor phase and on into a cooled volcanic plume. We measured three groups of metals in a small suite of samples collected on filters from the plumes of Kilauea (Hawaii, USA), Etna (Sicily), and Merapi (Java) volcanoes. These were the major, minor, and trace metals of the alkali and alkaline earth families (K, Rb, Cs, Ca, Sr, Ba), a group of ordinarily rare metals (Cd, Cu, In, Pb, Tl) that are related by their chalcophile affinities, and the radon daughter nuclides ²¹⁰Po, ²¹⁰Bi, and ²¹⁰Pb. The measurements show the range and some details of systematic melt-vapor fractionation within and between these groups of metals. In the plumes of all three volcanoes, the alkali metals are much more abundant than the alkaline earth metals. In the Kilauea plume, the alkali metals are at least six times more abundant than the alkaline earth metals, relative to abundances in the melt; at Etna, the factor is at least 300. Fractionations within each family are, commonly, also distinctive; in the Kilauea plume, in addition to the whole alkaline earth family being depleted, the heaviest metals of the family (Sr, Ba) are progressively more depleted than the light metal Ca. In plumes of fumaroles at Merapi, K/Cs ratios were approximately three orders of magnitude smaller than found in other earth materials. This may represent the largest observed enrichment of the “light ion lithophile” (LIL) metals. Changes in metal ratios were seen through the time of eruption in the plumes of Kilauea and Etna. This may reflect degree of degassing of volatiles, with which metals complex, from the magma bodies. At Kilauea, the changes in fractionation were seen over about three years; fractionation within the alkaline earth family increased, and that between the two families decreased, over that time.

All of the ordinarily rare chalcophile metals measured are extremely abundant in volcanic plumes, and Cd and Tl are enriched relative to the others. Indium is much more abundant in the plume of the hotspot volcano Kilauea than in the Etna plume (probably non-hotspot in character). It may be a useful indicator of the tapping of deep mantle zones, or could aid in the interpretation of reports of Pt group metals in exhalations from hot spot volcanoes. Indium in old glacial ice strata could help assess magnitude and variability of exhalations from hotspot volcanoes in past time. Strong melt-vapor fractionation of the alkali and alkaline earth metals may only be observed in plumes during quiescent degassing of volcanoes; when large amounts of ash or spatter (undifferentiated lava) enter the plume, its alkali and alkaline earth metal composition may approach that of the melt. Ratios among the chalcophile metals may not be much changed by addition of ash, because their concentrations in melt are so small, and masses of them in any plume may remain dominated by transfer across the melt-vapor interface.

Radon daughter nuclides give information about state of volcanic activity at time of sampling. The precisely known origins, ultratrace detectability, decay systematics, and wide variations in volatility of these species provide information about residence times, degassing and travel histories, and identities of melt bodies in volcanic systems.

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^☆: Paper presented at the symposium “Topics in Global Geochemistry” in honor of Clair C. Patterson on 3–4 December 1993 in Pasadena, California, USA.

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Fractionation of families of major, minor, and trace metals across the melt-vapor interface in volcanic exhalations☆

Abstract

Appl. Geochem.

Trace Constituents Emitted to the Atmosphere by Hawaiian Volcanoes Chemosphere

Geochim. Cosmochim. Acta

J. Volcan. Geotherm. Res.

Earth Planet Sci. Lett.

Earth Planet Sci. Lett.

Geochim. Cosmochim. Acta

J. Volc. Geotherm. Res.

J. Volcanol Geotherm. Res.

J. Volcanol. Geotherm. Res.

Earth Planet. Sci. Lett.

Geochim. Cosmochim. Acta

Earth Planet. Sci. Lett.

J. Volc. Geotherm. Res.

J. Volcanol. Geotherm. Res.

Geochim. Cosmochim Acta

Geochim. Cosmochim. Acta

J. Volc. Geotherm. Res.

Cesium-bearing volcanic glass of the Vershino-Darasun region (eastern Transbaikalia)

Volcanol Seis.

Metal composition of volcanic gas sublimates: Mauna Loa eruption of 1984

A mesoscale study of the elemental aerosol composition emitted from Mt. Etna volcano

Bull. Volcanol.

Comparison of Particles in the Fume from Eruptions of Kilauea, Mayon, and Arenal volcanoes

J. Geophys. Res.

Fluxes, sizes, morphology and compositions of particles in the Mt. Erebus volcanic plume, December 1983

J. Atmos. Chem.

Use of 7LiOH-impregnated filters for the collection of acidic gases and analysis by instrumental neutron activation analysis

Bull. Volcanol.

Vapor transport and deposition of trace elements in the 1984 Mauna Loa eruption

Trans. Amer. Geophys. Union

Interaction of volcanogenic fluids with host rocks and meteoric waters, and their relationship to mineralization

Bull. 131, New Mexico Bur. Mines Min. Res.

Alkali and alkaline earth metals: distribution and loss in a high Sierra Nevada watershed

GSA Bull.

Pathways and mass balance of natural cesium compared to some related metals in a rock-soil-water system

Concentrations of metals in very small volumes of soil solution

Nature

Metals and isotopes in plumes of subaerial volcanoes and oceanic spreading ridges, Hawaii

Distribution of metals between particle and gaseous forms in a volcanic plume

Bull. Volcanol.

Use of ⁷LiOH-impregnated filters for the collection of acidic gases and analysis by instrumental neutron activation analysis