Composition of barian mica in multiphase solid inclusions from orogenic garnet peridotites as evidence of mantle metasomatism in a subduction zone setting

Čopjaková, Renata; Kotková, Jana

doi:10.1007/s00410-018-1534-6

Cited by 14 publications

(12 citation statements)

References 65 publications

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“…The Ba 2+ Al 3+ ↔K 1+ Si 4+ substitution has already been described in previous works (e.g. Čopjaková and Kotková, 2018;Grapes, 1993;Kogarko et al, 2005).…”

Section: Substitution Mechanisms and Compositional Correlations In Micassupporting

confidence: 55%

“…It is supposed that the MSI were formed by interaction of mafic lithologies with metasomatic fluid or melt of crustal origin, possibly during interaction with subducting crustal material. The fluid or melt, combined with Mg, Fe, Al, and Cr, was extracted from pyroxenite during metasomatism in a manner similar to the genetically related rocks from the Saxothuringian and Moldanubian Domains (Faryad et al 2013, Borghini et al 2018, 2020Čopjaková and Kotková 2018;Naemura et al 2018). The fact that the MSI form chains crosscutting garnet crystals and are not correlated with the compositional zoning of garnet indicates that the interaction of the rocks with fluid/melt postdates garnet growth.…”

Section: Formation Of Msi and The Origin Of Ba CL And Co 2 Rich Fluid...mentioning

confidence: 99%

“…In mantle lithologies, Ba(-Cl)-rich micas and other Ba(-Cl)-rich phases are rare, but they are known from the matrix of garnet peridotite (Tumiati et al 2007). These phases specifically occur within multiphase solid inclusions, henceforth referred to as MSI, in garnet or spinel from (U)HP garnet pyroxenites, eclogites, peridotites, and chromitites (Zaccarini et al 2004;Faryad et al 2010;Borghini et al 2018Borghini et al , 2020Čopjaková and Kotková 2018;Naemura et al 2018;Kotková et al 2021).…”

Section: Introduction Occurrence and Origin Of Ba-(cl-) Bearing Micasmentioning

confidence: 99%

“…http://www.minsocam.org/ LILE and Cl-rich, sometimes potassic carbonatitic fluids or melts derived from a subducting crustal slab (Faryad et al 2013, Naemura et al 2018. Furthermore, the metasomatizing agent may be enriched in Mg, Fe, Al, and Cr derived from rocks in the mantle wedge (Tumiati et al 2007;Naemura et al 2009Naemura et al , 2018Borghini et al 2018Borghini et al , 2020Čopjaková and Kotková 2018;Kotková et al 2021).…”

Section: Introduction Occurrence and Origin Of Ba-(cl-) Bearing Micasmentioning

confidence: 99%

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Compositional trends in Ba-, Ti-, and Cl-rich micas from metasomatized mantle rocks of the Gföhl Unit, Bohemian Massif, Austria

Zelinková,

Racek,

Abart

2023

American Mineralogist

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Ba-, Ti-, and Cl-rich micas associated with other Ba-and/or Cl-rich minerals in the rock matrix or in garnet and clinopyroxene hosted multiphase solid inclusions (MSI) are observed in mantle-derived garnet pyroxenites. The micas show extremely high variability in chemical composition ranging between Ba-rich phlogopite, chloroferrokinoshitalite, and oxykinoshitalite. Elemental covariation trends in mineral chemical data reveal the principal substitution mechanisms responsible for the observed chemical variability. The substitution Ba 2+ Al 3+ ↔K 1+ Si 4+ associated with either OH 1-↔Cl 1or Ti 4+ 2O 2-↔Mg 2+ 2OH 1 links phlogopite to chloroferrokinoshitalite and oxykinoshitalite, respectively, whereas the substitution2Cl 1links chloroferrokinoshitalite to oxykinoshitalite. The preferred incorporation of Cl in Fe-rich mica and of Ti+O in Mg-rich mica indicates that XFe (Fe tot /Fe tot +Mg) exerts an important control on mica composition. The positive correlation of XFe with Cl led to the formation of possibly the most Clrich mica so far described classified as chloroferrokinoshitalite(XFe 0.88 , Ba 0.95 K 0.03 Fe 2.68 Mg 0.37 Al 1.91 Si 2.01 Cl 1.98 ) with 10.98 wt% Cl. Substantial substitution of OHby Cland This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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“…The Ba 2+ Al 3+ ↔K 1+ Si 4+ substitution has already been described in previous works (e.g. Čopjaková and Kotková, 2018;Grapes, 1993;Kogarko et al, 2005).…”

Section: Substitution Mechanisms and Compositional Correlations In Micassupporting

confidence: 55%

Section: Formation Of Msi and The Origin Of Ba CL And Co 2 Rich Fluid...mentioning

confidence: 99%

Section: Introduction Occurrence and Origin Of Ba-(cl-) Bearing Micasmentioning

confidence: 99%

Section: Introduction Occurrence and Origin Of Ba-(cl-) Bearing Micasmentioning

confidence: 99%

See 2 more Smart Citations

Compositional trends in Ba-, Ti-, and Cl-rich micas from metasomatized mantle rocks of the Gföhl Unit, Bohemian Massif, Austria

Zelinková,

Racek,

Abart

2023

American Mineralogist

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“…Finally, some garnet peridotite from the T‐7 borehole, Saxothuringian Zone, contains negative crystal‐shaped MSIs in garnet annuli (Čopjaková & Kotková, ). The mineral assemblage of these MSIs is, however, very different from the one reported for RUB and KLA samples, insofar as they contain in variable proportions: barian mica, amphibole, magnesite, and dolomite±other accessory phases.…”

Section: Discussionmentioning

confidence: 99%

Cryptic metasomatic agent measured in situ in Variscan mantle rocks: Melt inclusions in garnet of eclogite, Granulitgebirge, Germany

Borghini

Ferrero

O’Brien

et al. 2020

Journal Metamorphic Geology

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Garnet of eclogite (formerly termed garnet clinopyroxenite) hosted in lenses of orogenic garnet peridotite from the Granulitgebirge, NW Bohemian Massif, contains unique inclusions of granitic melt, now either glassy or crystallized. Analysed glasses and re‐homogenized inclusions are hydrous, peraluminous, and enriched in highly incompatible elements characteristic of the continental crust such as Cs, Li, B, Pb, Rb, Th, and U. The original melt thus represents a pristine, chemically evolved metasomatic agent, which infiltrated the mantle via deep continental subduction during the Variscan orogeny. The bulk chemical composition of the studied eclogites is similar to that of Fe‐rich basalt and the enrichment in LILE and U suggest a subduction‐related component. All these geochemical features confirm metasomatism. In comparison with many other garnet+clinopyroxene‐bearing lenses in peridotites of the Bohemian Massif, the studied samples from Rubinberg and Klatschmühle are more akin to eclogite than pyroxenites, as reflected in high jadeite content in clinopyroxene, relatively low Mg, Cr, and Ni but relatively high Ti. However, trace elements of both bulk rock and individual mineral phases show also important differences making these samples rather unique. Metasomatism involving a melt requiring a trace element pattern very similar to the composition reported here has been suggested for the source region of rocks of the so‐called durbachite suite, that is, ultrapotassic melanosyenites, which are found throughout the high‐grade Variscan basement. Moreover, the Th, U, Pb, Nb, Ta, and Ti patterns of these newly studied melt inclusions (MI) strongly resemble those observed for peridotite and its enclosed pyroxenite from the T‐7 borehole (Staré, České Středhoři Mountains) in N Bohemia. This suggests that a similar kind of crustal‐derived melt also occurred here. This study of granitic MI in eclogites from peridotites has provided the first direct characterization of a preserved metasomatic melt, possibly responsible for the metasomatism of several parts of the mantle in the Variscides.

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Crystallisation of trapped carbonate–silicate melts terminating at the carbonated solidus ledge: a record of carbon immobilisation mechanism in the lithospheric mantle

Haifler,

Kotková,

Čopjaková

2024

Contrib Mineral Petrol

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Orogenic peridotites in the crystalline basement of the northwestern Bohemian Massif contain multiphase solid inclusions (MSI), which are interpreted to be crystallisation products of trapped former carbonate–silicate melts metasomatizing their host rocks. We applied conventional thermobarometry and forward thermodynamic modelling to constrain the P–T evolution ranging from the peak metamorphic conditions of the investigated harzburgite and lherzolite, through entrapment of the melts in the outer parts of garnets, to the (re)-equilibration of the MSI assemblages. The peak conditions of c. 1100 °C/4.5–5.5 GPa are recorded by garnet cores and large pyroxene porphyroclasts. The melt entrapment, during which garnet outer parts grew, was associated with influx of the metasomatizing liquids and probably took place during the early stage of the exhumation. Thermodynamic model of amphibole-free MSI assemblage comprising kinoshitalite/Ba-rich phlogopite (approximated by phlogopite in the model), dolomite, magnesite, clinopyroxene, orthopyroxene, garnet and chromite provided robust estimate of P and T of its (re)-equilibration, c. 900–1000 °C, 1.8–2.2 GPa. Furthermore, the lack of olivine reflects co-existence of COH fluid with high X(CO2) = CO2/(CO2 + H2O) ≥ 0.6. Models employing identical P–T–X(CO2) parameters successfully reproduced the other two amphibole-bearing assemblages observed. The modelled stability fields show perfect alignment with a characteristic isobaric segment of the solidus curve of carbonated peridotite. This co-incidence implies that the (re)-equilibration corresponds to the termination of the melt crystallisation once the near-isothermal exhumation path intersected the solidus. Decreased solubility of silicates at the carbonated peridotite “solidus ledge”, inferred from the published experimental data, as well as concentric textures of some MSI indicates sequential crystallisation from the early silicates to late dolomite. The carbonated “solidus ledge” is a relatively narrow boundary in the lithospheric mantle capable of an abrupt immobilisation of fluxing or transported carbonated melts. The investigated rocks are estimated to store approximately 0.02 kg C/m3 (or 6 ppm C) occurring as carbonates in the MSI.

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Composition of barian mica in multiphase solid inclusions from orogenic garnet peridotites as evidence of mantle metasomatism in a subduction zone setting

Cited by 14 publications

References 65 publications

Compositional trends in Ba-, Ti-, and Cl-rich micas from metasomatized mantle rocks of the Gföhl Unit, Bohemian Massif, Austria

Compositional trends in Ba-, Ti-, and Cl-rich micas from metasomatized mantle rocks of the Gföhl Unit, Bohemian Massif, Austria

Cryptic metasomatic agent measured in situ in Variscan mantle rocks: Melt inclusions in garnet of eclogite, Granulitgebirge, Germany

Crystallisation of trapped carbonate–silicate melts terminating at the carbonated solidus ledge: a record of carbon immobilisation mechanism in the lithospheric mantle

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