Eclogite facies rocks of the Monotonous unit, clue to Variscan suture in the Moldanubian Zone (Bohemian Massif)

Faryad, Shah Wali; Jedlička, Radim; Collett, Stephen

doi:10.1016/j.lithos.2013.07.015

Cited by 44 publications

(27 citation statements)

References 68 publications

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“…12C and D). Faryad et al (2013) concludes the subduction in the "Moldanubian" zone to be younger than the "Saxothuringian" suture, which matches our predictions since the closure of the backarc is younger than the main subduction. Another important statement of this interpretation (Faryad et al, 2013) is that double subduction is inferred from eclogites/ granulites analysis, formation of which is reflected in our models (belts 2 and 3 on Fig.12D).…”

Section: Accepted Manuscriptsupporting

confidence: 87%

“…From the geodynamical point of view these two models Faryad et al, 2013) do not contradict with each other, the only feature to be verified is how much of subduction / underthrusting of the back arc is needed to produce a good match with the natural observations. Despite some discrepancies, our models mirror the most important orogenic stages identified in the Bohemian Massif.…”

Section: Accepted Manuscriptmentioning

confidence: 94%

“…Constant plate convergence is indeed a limitation of the numerical models, which neglected the influence of continental crust buoyancy on the subducting plate velocity. Another conceptual geodynamical model, developed by Faryad et al (2013), mentions the second subduction in the "Moldanubian" zone, where the backarc basin subducts beneath the magmatic arc in an opposite direction compared to the main oceanic "Saxothuringian" plate. This feature, which might be underestimated in the model of Schulmann et al (2014), is partially reflected in our models, where the dip of the backarc basin suture is very clearly pronounced ( Fig.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Geological studies (e.g. Windley, 1995;Brown et al, 2011;Wu and Zheng, 2013;Faryad et al, 2013;Schulmann et al, 2014;Gibson et al, 2011) and various analogue and numerical models (e.g. Vogt and Gerya, 2014;Sizova et al, 2014;Maierova et al, 2012Maierova et al, , 2014van Hunen and Allen, 2011;Gerya, 2014, and references therein) demonstrated that there is a large degree of complexity reflecting many factors such as subduction convergence rate and direction with respect to the plate boundaries, age and size of the tectonic units, lithological structure of the arc(s) and colliding continental margin(s).…”

Section: Introductionmentioning

confidence: 99%

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2D thermomechanical modelling of continent–arc–continent collision

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Section: Accepted Manuscriptsupporting

confidence: 87%

Section: Accepted Manuscriptmentioning

confidence: 94%

Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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2D thermomechanical modelling of continent–arc–continent collision

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“…The size of bodies ranges from several metres to almost 4 km in length. The estimated pressure conditions of eclogite, based on maximum jadeite content in omphacite, are 1.3–1.5 GPa at 657 ± 26 °C (Medaris et al ., ) and ~2.3 GPa at 630 °C based on the equilibrium reaction between omphacite–garnet–kyanite–quartz and intersecting isopleths of X Ca = Ca/(Ca + Mg + Fe + Mn) and X Fe = Fe/(Fe + Mg) from garnet (Faryad et al ., ). Higher temperatures of ~800 °C and pressures of 1.6–2.0 GPa, that are comparable with eclogite in the Gföhl Unit, were calculated for eclogites associated with pyroxenites near to the southern end of this 200 km long belt (O'Brien & Vrána, ; Faryad et al ., ).…”

Section: Geological Settingmentioning

confidence: 97%

Olivine‐bearing symplectites in fractured garnet from eclogite, Moldanubian Zone (Bohemian Massif) – a short‐lived, granulite facies event

Faryad

Fišera²

2015

Journal Metamorphic Geology

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Recent petrological studies on high-pressure (HP)-ultrahigh-pressure (UHP) metamorphic rocks in the Moldanubian Zone, mainly utilizing compositional zoning and solid phase inclusions in garnet from a variety of lithologies, have established a prograde history involving subduction and subsequent granulite facies metamorphism during the Variscan Orogeny. Two temporally separate metamorphic events are developed rather than a single P-T loop for the HP-UHP metamorphism and amphibolite-granulite facies overprint in the Moldanubian Zone. Here further evidence is presented that the granulite facies metamorphism occurred after the HP-UHP rocks had been exhumed to different levels of the middle or upper crust. A medium-temperature eclogite that is part of a series of tectonic blocks and lenses within migmatites contains a well-preserved eclogite facies assemblage with omphacite and prograde zoned garnet. Omphacite is partly replaced by a symplectite of diopside + plagioclase + amphibole. Garnet and omphacite equilibria and pseudosection calculations indicate that the HP metamorphism occurred at relatively low temperature conditions of~600°C at 2.0-2.2 GPa. The striking feature of the rocks is the presence of garnet porphyroblasts with veins filled by a granulite facies assemblage of olivine, spinel and Ca-rich plagioclase. These minerals occur as a symplectite forming symmetric zones, a central zone rich in olivine that is separated from the host garnet by two marginal zones consisting of plagioclase with small amounts of spinel. Mineral textures in the veins show that they were first filled mostly by calcic amphibole, which was later transformed into granulite facies assemblages. The olivine-spinel equilibria and pseudosection calculations indicate temperatures of~850-900°C at pressure below 0.7 GPa. The preservation of eclogite facies assemblages implies that the granulite facies overprint was a short-lived process. The new results point to a geodynamic model where HP-UHP rocks are exhumed to amphibolite facies conditions with subsequent granulite facies heating by mantle-derived magma in the middle and upper crust.

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Re-equilibration history and P–T path of eclogites from Variscan Sardinia, Italy: a case study from the medium-grade metamorphic complex

Cruciani

Franceschelli

Groppo

et al. 2014

Int J Earth Sci (Geol Rundsch)

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Retrogressed eclogites are hosted within the Variscan Low-to Medium-Grade Metamorphic Complex near Giuncana, north-central Sardinia. These rocks are medium-to finegrained with garnet and amphibole as the most abundant mineral phases along with clinopyroxene, plagioclase, quartz, biotite, chlorite, epidote, ilmenite, rutile and titanite. Four stages of mineralogical re-equilibration have been distinguished. The stage I is characterized by the occurrence of omphacite, epidote, quartz, amphibole, rutile and ilmenite in garnet poikiloblasts. The stage II is characterized by two types of symplectitic microstructures: (i) amphibole + quartz symplectite, and (ii) clinopyroxene + plagioclase ± amphibole symplectite. The first symplectite type replaces omphacite included in garnet, whereas the second one is widespread in the matrix.Biotite droplets and/or lamellae intimately growing with fine-grained plagioclase resemble biotite + plagioclase symplectite after phengite. The stage III is characterized by the widespread formation of amphibole: (i) as zoned porphyroblasts in the matrix, (ii) as corona-type microstructure replacing garnet. Subordinate plagioclase (oligoclase) is also present in the amphibole corona. The stage IV is characterized by the local formation of biotite replacing garnet, actinolite, chlorite, albite and titanite. P-T pseudosections calculated with Perple_X give P-T conditions 580

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Eclogite facies rocks of the Monotonous unit, clue to Variscan suture in the Moldanubian Zone (Bohemian Massif)

Cited by 44 publications

References 68 publications

2D thermomechanical modelling of continent–arc–continent collision

2D thermomechanical modelling of continent–arc–continent collision

Olivine‐bearing symplectites in fractured garnet from eclogite, Moldanubian Zone (Bohemian Massif) – a short‐lived, granulite facies event

Re-equilibration history and P–T path of eclogites from Variscan Sardinia, Italy: a case study from the medium-grade metamorphic complex

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