Pyroxene-carbonate reactions in the upper mantle

Brey, Gerhard P.; Brice, William R.; Ellis, David J.; Green, David H.; Harris, K.L.; Ryabchikov, I. D.

doi:10.1016/0012-821x(83)90071-7

Cited by 207 publications

(69 citation statements)

References 26 publications

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“…These fluids may then metasomatically enrich the shallower levels of the mantle «70 km) by amphibolitization, producing an appropriate source for alkaline magmatism. Figure 12.6 shows the Olafsson & Eggler solidus in relation to the positions of the major carbonation reactions of Brey et al (1983). Magnesite is the stable carbonate phase present at depths greater than about 140 km, whereas dolomite is stable Figure 12.6 The peridotite solidus in the presence of small amounts of H20 and CO2 (Olafsson & Eggler 1983) in relation to tlie major mantle carbonation reactions (Brey et al 1983).…”

Section: Simplified Petrogenetic Modelmentioning

confidence: 96%

“…Unfortunately, there is some conflict concerning phase relationships in the system peridotite-HzO-COz (Brey et al 1983, Olafsson & Eggler 1983, Wyllie 1987) and the compositions of the partial melts have been inadequately characterized. However, there is a general consensus that partial melts of phologopite peridotite will be K20-and MgO-rich, while those of carbonated peridotite will be carbonate-rich.…”

Section: Simplified Petrogenetic Modelmentioning

confidence: 99%

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Igneous Petrogenesis

Wilson

2000

328

383

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Section: Simplified Petrogenetic Modelmentioning

confidence: 96%

Section: Simplified Petrogenetic Modelmentioning

confidence: 99%

Igneous Petrogenesis

Wilson

2000

328

383

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“…Eggler (1989) points out that near-solidus melts formed from phlogopite-carbonate peridotite are predicted from work on simple systems to be carbonatitic. Thus the work of Brey et al (1983) and Olafsson and Eggler (1983) show that with increasing pressure phlogopite-carbonate peridotite produces liquids of more magnesian compositions and that the carbonate mineralogy changes at about 32 kbar from dolomite to magnesite. Partial melting of a phlogopite-carbonate peridotite at pressures > 32 kbar is, therefore, capable of producing a carbonatitic melt from which magnesite would crystallize as a primary phase.…”

Section: Discussionmentioning

confidence: 99%

Carbonates of the magnesite–siderite series from four carbonatite complexes

Buckley

Woolley

1990

Mineral. mag.

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Carbonates of the magnesite-siderite series have been found and analysed in carbonatites from the Lueshe, Newania, Kangankunde, and Chipman Lake complexes. This series has been represented until now only by a few X-ray identifications of magnesite and three published analyses of siderite and breunnerite (magnesian siderite). Most of the siderite identified in carbonatites in the past has proved to be ankerite, but the new data define the complete solid-solution series from magnesite to siderite. They occur together with dolomite and ankerite and in one rock with calcite. The magnesites, ferroan magnesites and some magnesian siderites may be metasomatic/hydrothermal in origin but magnesian siderite from Chipman Lake appears to have crystallized in the two-phase calcite + siderite field in the subsolidus CaCO3-MgCO3-FeCO3 system. Textural evidence in Newania carbonatites indicates that ferroan magnesite, which co-exists with ankerite, is a primary liquidus phase and it is proposed that the Newania carbonatite evolved directly from a Ca-poor, Mg-rich carbonatitic liquid generated by partial melting of phlogopite-carbonate peridotite in the mantle at pressures >32 kbar.K EYWO R D S: carbonate, carbonatite complexes, magnesite, siderite, breunnerite.

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“…The result of this metasomatism is the oxidation of local zones in the mid-to lowermost lithosphere beneath the LDG kimberlite field to levels conducive to the stabilization of carbonate. The expected stable carbonate phase is Mg-rich in any four-phase peridotite assemblage, i.e., dolomite (e.g., Wyllie and Huang 1975;Dalton and Presnall 1998a) or magnesite at higher pressure (Brey et al 1983), and the melt produced from such carbonated peridotites is always dolomitic in composition (e.g., Irving and Wyllie 1975;Brey et al 2008). However, LDG kimberlites, and kimberlites globally, are mostly dominated by calcite (e.g., Skinner and Clement 1979;Armstrong et al 2004), as are the early kimberlite melts trapped as polymineralic inclusions in LDG megacrysts.…”

Section: General Role Of Decarbonation Reactions In Producing Calcitementioning

confidence: 99%

The evolution of calcite-bearing kimberlites by melt-rock reaction: evidence from polymineralic inclusions within clinopyroxene and garnet megacrysts from Lac de Gras kimberlites, Canada

Bussweiler

Stone

Pearson

et al. 2016

Contrib Mineral Petrol

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inclusion trails surround the inclusions. In Cr-pyropes, the inclusions additionally contain Al-spinel, clinopyroxene, and dolomite. The major and trace element compositions of the inclusion phases are generally consistent with the early stages of kimberlite differentiation trends. Extensive chemical exchange between the host phases and the inclusions is indicated by enrichment of the inclusions in major components of the host crystals, such as Cr 2 O 3 and Al 2 O 3 . This chemical evidence, along with phase equilibria constraints, supports the proposal that the inclusions within Cr-diopside record the decarbonation reaction: dolomitic melt + diopside → forsterite + calcite + CO 2 , yielding the observed inclusion mineralogy and producing associated (CO 2 -rich) fluid inclusions. Our study of polymineralic inclusions in megacrysts provides clear mineralogical and chemical evidence for an origin of kimberlite that involves the reaction of high-pressure dolomitic melt with diopside-bearing mantle assemblages producing a lower-pressure melt that crystallizes a calcite-dominated assemblage in the crust.

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Pyroxene-carbonate reactions in the upper mantle

Cited by 207 publications

References 26 publications

Igneous Petrogenesis

Igneous Petrogenesis

Carbonates of the magnesite–siderite series from four carbonatite complexes

The evolution of calcite-bearing kimberlites by melt-rock reaction: evidence from polymineralic inclusions within clinopyroxene and garnet megacrysts from Lac de Gras kimberlites, Canada

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