The partitioning of trace elements between clinopyroxene and trachybasaltic melt during rapid cooling and crystal growth

Mollo, Silvio; Blundy, Jon; Iezzi, Gianluca; Scarlato, Piergiorgio; Langone, Antonio

doi:10.1007/s00410-013-0946-6

Cited by 93 publications

(86 citation statements)

References 79 publications

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“…Type 1 crystals form along the entire magmatic column, from 790 to 250 MPa. An alternative interpretation comes from Mollo et al (2013), which have demonstrated that, during the rapid growth of Etnean cpx, the crystal composition is progressively enriched in tetrahedral Al, Ti, and Na and depleted in Fe 2+ , Ca, and Mg. The cpx chemistry is controlled by the substitution of M2 (Mg, Fe 2+ ) with M1 (Al, Fe 3+ ) coupled with the substitution of Si with Al in the tetrahedral site to form the Tschermak components.…”

Section: Magma Feeding Systemmentioning

confidence: 94%

Mt. Etna plumbing system revealed by combined textural, compositional, and thermobarometric studies in clinopyroxenes

Giacomoni

Coltorti

Bryce

et al. 2016

Contrib Mineral Petrol

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International audienceCoupled textural and in situ geochemical studies of clinopyroxene (cpx) phenocrysts, from both historical and recent eruptions of Mt. Etna volcano, provide a means to investigate the processes occurring in the deepest portion of the feeding system (>10 km depth). Five distinct textures were recognized: (1) normal oscillatory zoning, (2) normal zoning with Fe-rich rim, (3) sieve-textured core, (4) reverse oscillatory zoning, and (5) dusty rim. Electron microprobe analyses indicate an almost constant diopside–augite composition, with a slight enrichment in the enstatite for more recent erupted cpx. Core-to-rim compositional profiles, performed along the cpx, reveal distinct compositional characteristics. Normal oscillatory zoning is often characterized by a sharp increase in FeO (Δ ~ 2 wt%) accompanied by a drop in Al2O3 on the outermost 30 μm. Reverse oscillatory zoning, by contrast, exhibits a drop in FeO, Al2O3 (Δ ~ 2 wt%), and a remarkable crystal rim increase in MgO (up to 5 wt%). Similar compositional changes are evident in dusty-textured rims, which are characterized by dissolution edges and overgrowth containing glass pockets and channels. No significant compositional variations have been observed across crystals with sieve-textured cores. Trace element concentrations show enrichments in Sr, La, Zr, and REE, together with a decreasing La/Yb ratio (from ~7 to ~4) in rims of normally zoned crystals. Cpx with reverse zoning and dusty rims has low Sr, La, Zr, and REE contents toward crystal rims. Thermometers and barometers, based on equilibrium cpx-melt pairs, suggest that cpx cores start nucleating at 720 MPa, with the majority of them forming between 600 and 400 MPa but continuing to crystallize until very shallow depths (<100 MPa). Normal oscillatory-zoned phenocrysts surrounded by rims form at pressures shallower than 400 MPa, while reverse zoning and dusty rims occur between 400 and 500 MPa. Coupled petrologic and thermobarometric studies on both clinopyroxenes and plagioclases, associated with detailed textural and in situ geochemical analyses, are promising tools to reconstruct the entire magma ascent path beneath open-system volcanoes. At Mt. Etna, two distinct processes could account for the observed textures: Fe-rich rims in normal oscillatory-zoned crystals can be related to decompression-induced crystallization, while reverse zoning and dusty rims can be produced by mixing with a more basic magma at 400–500 MPa (i.e., ~10 km). Textural features are not restricted to a particular evolutionary phase of the volcano, which suggest that the deep feeding system has not changed significantly since the first alkaline volcanic phase

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Section: Magma Feeding Systemmentioning

confidence: 94%

Mt. Etna plumbing system revealed by combined textural, compositional, and thermobarometric studies in clinopyroxenes

Giacomoni

Coltorti

Bryce

et al. 2016

Contrib Mineral Petrol

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“…According to a number of studies, under kinetically-controlled crystallization conditions, Al 3+ substitutes for Si 4+ in clinopyroxene tetrahedral site (see Fig. 2c) causing charge imbalances that are compensated by increasing concentrations of highly charged cations, such as Ti (Smith and Lindsley, 1971;Grove and Bence, 1977;Grove and Raudsepp, 1978;Coish and Taylor, 1979;Gamble and Taylor, 1980;Blundy et al, 1998;Hill et al, 2000;Wood and Blundy, 2001;Lofgren et al, 2006;Mollo et al, 2013d;Scarlato et al, 2014). In our compositions, the partitioning of Ti between clinopyroxene and melt compositions (i.e., cpx-melt K Ti ) increases by a factor of four from lava fountains to pahoehoe to aa lavas (Fig.…”

Section: The Thermal Path Of Eruptionsmentioning

confidence: 97%

“…5b), showing values out of the equilibrium range experimentally-derived for Etnean compositions (cf. Mollo et al, 2013d). Additionally, taking into account the close textural relationship between clinopyroxene and titanomagnetite, it is interesting to note that as long as Ti is preferentially incorporated in clinopyroxene (Fig.…”

Section: The Thermal Path Of Eruptionsmentioning

confidence: 97%

Clinopyroxene and titanomagnetite cation redistributions at Mt. Etna volcano (Sicily, Italy): Footprints of the final solidification history of lava fountains and lava flows

et al. 2015

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“…Water-saturated experiments were conducted by Metrich and Rutherford (1998) between 1009 and 1135 °C, for P H2O = P total varying from 27 to 120 MPa under G-CH, QFM and NNO buffering conditions. Anhydrous and water-undersaturated phase equilibrium data were obtained at 1000-1130 °C, 0.1-500 MPa, 0-2.8 wt.% H 2 O, and NNO-NNO+1.5 buffer by Dolfi and Trigila (1983) and Mollo et al (2010Mollo et al ( , 2011bMollo et al ( , 2013bMollo et al ( , 2013c, also comprising new data from this study.…”

Section: Experimental Datasetmentioning

confidence: 99%

Reconstruction of magmatic variables governing recent Etnean eruptions: Constraints from mineral chemistry and P–T–fO2–H2O modeling

Mollo

Giacomoni

Coltorti

et al. 2015

Lithos

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The partitioning of trace elements between clinopyroxene and trachybasaltic melt during rapid cooling and crystal growth

Cited by 93 publications

References 79 publications

Mt. Etna plumbing system revealed by combined textural, compositional, and thermobarometric studies in clinopyroxenes

Mt. Etna plumbing system revealed by combined textural, compositional, and thermobarometric studies in clinopyroxenes

Clinopyroxene and titanomagnetite cation redistributions at Mt. Etna volcano (Sicily, Italy): Footprints of the final solidification history of lava fountains and lava flows

Reconstruction of magmatic variables governing recent Etnean eruptions: Constraints from mineral chemistry and P–T–fO2–H2O modeling

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