Dissolution of orthopyroxene in basanitic magma between 0.4 and 2 GPa: further implications for the origin of Si-rich alkaline glass inclusions in mantle xenoliths

Shaw, Cliff S. J.

doi:10.1007/s004100050501

Cited by 101 publications

(55 citation statements)

References 30 publications

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“…Many mantle xenolith-hosted glasses display far more 'extreme' compositions than glasses from our study (e.g. Shaw 1999). In part this reflects a combination of factors like differences in melting regimes and the presence of plume or subduction-related components (e.g.…”

Section: Comparison With Natural Quenched Liquidsmentioning

confidence: 47%

Melt variability in percolated peridotite: an experimental study applied to reactive migration of tholeiitic basalt in the upper mantle

Bleeken

Müntener

Ulmer³

2010

Contrib Mineral Petrol

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Melt-rock reaction in the upper mantle is recorded in a variety of ultramafic rocks and is an important process in modifying melt composition on its way from the source region towards the surface. This experimental study evaluates the compositional variability of tholeiitic basalts upon reaction with depleted peridotite at uppermost-mantle conditions. Infiltration-reaction processes are simulated by employing a three-layered set-up: primitive basaltic powder ('melt layer') is overlain by a 'peridotite layer' and a layer of vitreous carbon spheres ('melt trap'). Melt from the melt layer is forced to move through the peridotite layer into the melt trap. Experiments were conducted at 0.65 and 0.8 GPa in the temperature range 1,170-1,290°C. In this P-T range, representing conditions encountered in the transition zone (thermal boundary layer) between the asthenosphere and the lithosphere underneath oceanic spreading centres, the melt is subjected to fractionation, and the peridotite is partially melting (T s * 1,260°C). The effect of reaction between melt and peridotite on the melt composition was investigated across each experimental charge. Quenched melts in the peridotite layers display larger compositional variations than melt layer glasses. A difference between glasses in the melt and peridotite layer becomes more important at decreasing temperature through a combination of enrichment in incompatible elements in the melt layer and less efficient diffusive equilibration in the melt phase. At 1,290°C, preferential dissolution of pyroxenes enriches the melt in silica and dilutes it in incompatible elements. Moreover, liquids become increasingly enriched in Cr 2 O 3 at higher temperatures due to the dissolution of spinel. Silica contents of liquids decrease at 1,260°C, whereas incompatible elements start to concentrate in the melt due to increasing levels of crystallization. At the lowest temperatures investigated, increasing alkali contents cause silica to increase as a consequence of reactive fractionation. Pervasive percolation of tholeiitic basalt through an upper-mantle thermal boundary layer can thus impose a high-Si 'low-pressure' signature on MORB. This could explain opx ? plag enrichment in shallow plagioclase peridotites and prolonged formation of olivine gabbros.

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Section: Comparison With Natural Quenched Liquidsmentioning

confidence: 47%

Melt variability in percolated peridotite: an experimental study applied to reactive migration of tholeiitic basalt in the upper mantle

Bleeken

Müntener

Ulmer³

2010

Contrib Mineral Petrol

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“…Orthopyroxene III is extremely scarce (xenolith 3334 only) and forms cores of clinopyroxene III. Its chemical composition is identical to that of orthopyroxene I and we suggest it represents fragments of orthopyroxene I not fully reacted with an alkaline melt (Shaw 1999). Spinel III has partly highly chromian compositions.…”

Section: Phases Forming the Fine-grained Aggregates And Clinopyroxenementioning

confidence: 66%

“…Significant increase in Ca content in Steinberg xenoliths may however point to reaction under high pressure conditions . Orthopyroxene is dissolved during reaction with alkaline silicate melt and secondary clinopyroxene is formed (Shaw 1999) as vermicular rims of clinopyroxene III on orthopyroxene I. Therefore, we suggest that the fine-grained aggregates result from reaction between peridotite and alkaline silicate melt at high pressures.…”

Section: Phases Forming the Fine-grained Aggregates And Clinopyroxenementioning

confidence: 94%

“…3f) are characteristic for this xenolith and occur commonly in mantle xenoliths from SW Poland (e.g., Matusiak-Małek et al 2010;2014). Shaw (1999) attributed their formation to dissolution of orthopyroxene I by Upton et al (2011) reaction with silica-poor alkaline melt. In most Steinberg xenoliths the rims are rather narrow, but in dunite 3327 they reach up to 100 μm, suggesting longer reaction time and/or better supply of alkaline melt to the reaction site.…”

Section: Peridotite-melt Reactions: Origin Of Bb^dunitementioning

confidence: 99%

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Depleted subcontinental lithospheric mantle and its tholeiitic melt metasomatism beneath NE termination of the Eger Rift (Europe): the case study of the Steinberg (Upper Lusatia, SE Germany) xenoliths

et al. 2015

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The ca. 30 Ma Steinberg basanite occurs at the NE termination of the Eger (Ohře) Rift in the NW Bohemian Massif, Central Europe, and belongs to the Cenozoic alkaline Central European Volcanic Province. The basanite hosts a suite of mantle xenoliths, most of which are harzburgites containing relatively magnesian olivine (Fo 90.5-91.6) and Alpoor (0.04-0.13 a pfu) orthopyroxene (mg# 0.90-0.92). Some of these harzburgites also contain volumetrically minor clinopyroxene (mg# 0.92-0.95, Al 0.03-0.13 a pfu) and have U-shaped LREE-enriched REE patterns. The Steinberg harzburgites are typical for the Lower Silesian -Upper Lusatian domain of the European subcontinental lithospheric mantle. They represent residual mantle that has undergone extensive partial melting and was subsequently affected by mantle metasomatism by mixed carbonatite-silicate melts. The Steinberg xenolith suite comprises also dunitic xenoliths affected by metasomatism by melt similar to the host basanite, which lowered the Fo content in olivine to 87.6 %. This metasomatism happened shortly before xenolith entrainment in the erupting lava. One of the xenoliths is a wehrlite (olivine Fo 73 %, clinopyroxene mg# 0.83-0.85, subordinate orthopyroxene mg# 0.76-0.77). Its clinopyroxene REE pattern is flat and slightly LREE-depleted. This wehrlite is considered to be a tholeiitic cumulate. One of the studied harzburgites contains clinopyroxene with similar trace element contents to those in wehrlite. This type of clinopyroxene records percolation of tholeiitic melt through harzburgite. The tholeiitic melt might be similar to Cenozoic continental tholeiites occurring in the Central European Volcanic Province (e.g., Vogelsberg, Germany).

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“…( Neumann and Wulff Pedersen 1997;Wulff Pedersen et al, 1996, 1999 (Sen et al, 1996) (Ionov et al, 1993;Schiano et al, 1992) ( Kogarko et al, 2001) 2.…”

mentioning

confidence: 99%

Silicic glasses trapped in peridotite xenoliths: an insight into melting and metasomatism processes in mantle peridotite

Ishimaru¹,

Arai²

2005

Japanese Magazine of Mineralogical and Petrological Sciences

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Dissolution of orthopyroxene in basanitic magma between 0.4 and 2 GPa: further implications for the origin of Si-rich alkaline glass inclusions in mantle xenoliths

Cited by 101 publications

References 30 publications

Melt variability in percolated peridotite: an experimental study applied to reactive migration of tholeiitic basalt in the upper mantle

Melt variability in percolated peridotite: an experimental study applied to reactive migration of tholeiitic basalt in the upper mantle

Depleted subcontinental lithospheric mantle and its tholeiitic melt metasomatism beneath NE termination of the Eger Rift (Europe): the case study of the Steinberg (Upper Lusatia, SE Germany) xenoliths

Silicic glasses trapped in peridotite xenoliths: an insight into melting and metasomatism processes in mantle peridotite

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