Volcanic-related alteration and geochemistry of Iwodake volcano, Satsuma-Iwojima, Kyushu, SW Japan

Hamasaki, Satoshi

doi:10.1186/bf03353021

Cited by 18 publications

(19 citation statements)

References 17 publications

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“…The soluble B compounds likely form by sublimation of gaseous B compounds from the magma. Available information on the behavior of Mo and W in magmatogenic processes suggests that a fraction of the Mo and W in magmas is hosted in volatile compounds (Bykova et al, 1995;Hamasaki, 2002). If these compounds do not escape into the atmosphere from rapidly solidifying lavas, like B, they would sublime upon cooling of the lava and possibly form soluble compounds on the surfaces of mineral grains.…”

Section: Discussionmentioning

confidence: 97%

“…The correlation of Mo and W with K indicates that all three elements behave essentially in the same way during , 1985). It is known that both Mo and W are enriched in the residual liquid of magmas and they form volatile compounds at magmatic temperatures, as shown by their enrichment in minerals formed around fumaroles of active volcanoes (Bykova et al, 1995;Hamasaki, 2002). The correlation of Mo and W with K, however, indicates that insignificant fractions of Mo and W are lost from the magma through degassing during lava eruption and consolidation.…”

Section: Distributions Of Mo and W In Basaltic To Silicic Volcanicsmentioning

confidence: 96%

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Molybdenum and tungsten in volcanic rocks and in surface and <100°C ground waters in Iceland

Arnórsson

Öskarsson

2007

Geochimica et Cosmochimica Acta

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Section: Discussionmentioning

confidence: 97%

Section: Distributions Of Mo and W In Basaltic To Silicic Volcanicsmentioning

confidence: 96%

Molybdenum and tungsten in volcanic rocks and in surface and <100°C ground waters in Iceland

Arnórsson

Öskarsson

2007

Geochimica et Cosmochimica Acta

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“…Alunite is formed between 15 and 400 ºC by the action of sulphate, which is generated from pyrite or by action of fumaroles. Al and K of Alunite can be leached from the wall rock and transported by acid solutions, which permeate into the surface (Hamasaki, 2002). In the magmatic/hydrothermal environment, beginning at 400 ºC, and in the presence of water, SO 2 disproportionate as follow (Holland, 1965):…”

Section: Hydrated Sulphatesmentioning

confidence: 99%

Hydrothermal alteration, fumarolic deposits and fluids from Lastarria Volcanic Complex: A multidisciplinary study

Aguilera

Layana

Rodríguez-Díaz

et al. 2016

andgeo

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ABSTRACT.A multidisciplinary study that includes processing of Landsat ETM+ satellite images, chemistry of gas condensed, mineralogy and chemistry of fumarolic deposits, and fluid inclusion data from native sulphur deposits, has been carried out in the Lastarria Volcanic Complex (LVC) with the objective to determine the distribution and characteristics of hydrothermal alteration zones and to establish the relations between gas chemistry and fumarolic deposits. Satellite image processing shows the presence of four hydrothermal alteration zones, characterized by a mineral assemblage constituted mainly by clay minerals, alunite, iron oxides, and more subordinated ferrous minerals and goethite. Hydrothermal alteration zones present in the Lastarria sensu stricto volcano are directly related to the recent fumarolic activity. Geochemistry of fumarolic gas condensed, obtained from two fumaroles at temperatures between 328 and 320 °C, has allowed detecting 37 diverse elements corresponding to halogens, chalcophiles, siderophiles, alkali metals, alkali earth metals and Rare Earth Elements (REE), with concentrations that vary widely between 5,620 ppm (chlorine) and 0.01 ppm (Mo, Ag, Sn, Pb, Se, Mg and Cr). Logarithm of Enrichment Factor (log EF i ) for each element present values between 6.35 (iodine) and <1 (K, Na, Ca, Fe and Al). Those elements are originated primarily from a magmatic source, whereas at shallow level a hydrothermal source contributes typical rock-related elements, which are leached from the wall rock by a strong interaction with hyperacid fluids. Mostly of elements detected are transported to the surface in the fumarolic emissions as gaseous species, while very few elements (Mg, Ca and Al) are transported in silicate aerosols. A wide spectrum of minerals are present in the fumarolic deposits, which are constituted by sublimates and incrustations, and the main minerals phases are distributed in six mineral families, corresponding to sulphates, hydrated sulphates, sulphides, halides, carbonates, silicates and native element minerals. The sublimate/incrustation minerals are dominated by the presence of sulphate, sulphur, chlorine and diverse rock-related elements, which are formed by processes that include a. oxidation of gaseous phase; b. strong rock-fluid interaction; c. dissolution of silicate minerals and volcanic glass; d. gas-water interaction; e. deposition/precipitation of saline bearing minerals; f. oxidation of sublimates/incrustations to form secondary minerals and g. remobilization of sulphur deposits by meteoric water. Despite that sublimate/ incrustation minerals are dominated by rock-related elements, its chemistry shows high contents of high-volatile elements as As, Sb, Cd, among others. Fluid inclusions studies carried out in thin pseudobanded native sulphur from fumarolic deposits, by use of Raman and infrared spectroscopy combined with microthermometry analyses, provided evidence of H 2 O, CO 2 , H 2 S, SO 4 , COS bearing fluids, homogenization temperatures around 110 °C and salinities v...

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“…The summit area of the main Iwodake lava dome is strongly silicified by volcanic gases (Hamasaki, 2002), indicating that degassing has continued for a long time. An old manuscript "Heike Monogatari," written about 800 years ago, indicates that intense volcanic gas emission and depo- Burnham, 1979), CO 2 in rhyolite at 1200 • C (Fogel and Rutherford, 1990) and CO 2 in basalt at 1200 • C (Stolper and Holloway, 1988).…”

Section: Volcanic Gasesmentioning

confidence: 99%

Degassing process of Satsuma-Iwojima volcano, Japan: Supply of volatile components from a deep magma chamber

2014

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Satsuma-Iwojima volcano continuously releases magmatic volatiles from the summit of Iwodake, a rhyolitic lava dome. The temperature of fumaroles is high, between 800• and 900• C, and the water-rich composition of volcanic gases has not changed essentially over the past 10 years. Sulfur dioxide flux measured by COSPEC is almost constant with an average of 550 t/d since 1975. The present volcanic gas is likely degassed from a rhyolitic magma whose composition is similar to that erupted in 1934, 2 km east of Satsuma-Iwojima. Comparison of silicate melt inclusions and volcanic gas compositions indicates that the magma degassing pressure is very low, implying magma-gas separation at a very shallow level. The mass rate of magma degassing is estimated at 10 m 3 /s using the volatile content of the magma and the fluxes of magmatic volatiles. The rhyolitic parental magma is volatile-undersaturated in the deep magma chamber, as suggested by melt inclusion studies. Magma convection in a conduit, driven by the density difference between higher density degassed and lower density non-degassed magmas, explains the high emission rate of magmatic volatiles released at shallow depth from such a magma chamber, that is gas-undersaturated at depth. Model calculations require the conduit diameter to be greater than 50 m as a necessary condition for convection of the rhyolitic magma. Long-term convective degassing has resulted in the rhyolitic magma in the deep chamber to become depleted in volatile components. The melt-inclusion studies indicate that the rhyolitic magma responsible for discharging the present volcanic gas has been degassed during the long degassing history of the volcano and is now supplied with CO 2 -rich volatile components from an underlying basaltic magma. The total volcanic gas flux over 800 years requires degassing of 80-120 km 3 of basaltic magma.

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Volcanic-related alteration and geochemistry of Iwodake volcano, Satsuma-Iwojima, Kyushu, SW Japan

Cited by 18 publications

References 17 publications

Molybdenum and tungsten in volcanic rocks and in surface and <100°C ground waters in Iceland

Molybdenum and tungsten in volcanic rocks and in surface and <100°C ground waters in Iceland

Hydrothermal alteration, fumarolic deposits and fluids from Lastarria Volcanic Complex: A multidisciplinary study

Degassing process of Satsuma-Iwojima volcano, Japan: Supply of volatile components from a deep magma chamber

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