Metamorphic Petrology Research Group
Metamorphic Petrology Research Group (MPRG) is composed of academic members of the Institute of Petrology and Strutural Geology and their post-graduate students. Our aim is to the study of textural and phase relations amongst minerals in metamorphic rocks. For this purpose, we use different modern approaches, mainly description of the distribution of elements in minerals and their behavior during metamorphosis, geospeedometry, thermodynamical modelling etc. The results of our research should be the understanding of processes of evolution and exhumation of UHP rocks and of geodynamics of the collision orogenic zones.
Main topics of our research:
- Exhumation of UHP rocks in collision orogeny
- Eclogites and ultrahigh-pressure rocks of the Bohemian Massif
- Petrological aspects related to partial melting of granitic rocks in (U)HP conditions
- Mass balance and major and trace elements zoning in atoll garnet from eclogite facies rocks
- Record of metamorphic and metasomatic processes at the contact of the felsic and mafic rocks in HT conditions
- The Jurassic Meliata Zone (Western Carpathians)
- Basement xenolites in metagranite from Panshir Valley, Western Hindu Kush
Shah Wali Faryad
MPRG Leader, professor
Professor of petrology
Phase and textural relations of metamorphic minerals, UHPM rocks
Professor of geophysics
Anisotropy of magnetic susceptibility in mafic and ultramafic rocks
Scanning electron microscopy and microanalysis
Distribution of major and trace elements in metamorphic rocks
Scanning electron microscopy and microanalysis
Thermodynamical modeling, HP and HT metamorphosis
mass balance of elements during metamorphic processes, high-pressure rocks
Metasomatic and metamorphic interaction between felsic and mafic lithologies
High grade rocks and Metamorphism in Western Hindu Kush
Members of our research team are leaders of the laboratories equipped with scanning electron microscope TESCAN Vega and electron microprobe FEG-EPMA JXA 8530F by JEOL. These machines allow us to obtain qualitative, but mainly quantitative analyses of major and trace elements from solid substances as well as compositional mapping and imaging by SE, BSE, CL, EBSD detectors.
Exhumation of UHP rocks in collision orogeny
Our research results from subduction and collision orogenies, particularly from the Bohemian Massif, showed that crustal rocks with fragments of the partially cooled mantle wedge (a) undergo recrystallization during their subduction to (U)HP conditions (path 1a and 1b, in b). Their exhumation (path 2 in b) is governed by eduction of buoyant crustal material and slab breakoff that subsequently result in mantle upwelling (c) and heating of partially exhumed (U)HP rocks (path 3 in b).
- Faryad, S.W., Baldwin, S.L. Jedlicka, R. and Ježek, J. 2019. Two-stage garnet growth in coesite eclogite from the southeastern Papua New Guinea (U)HP terrane and its geodynamic significance. Contributions to Mineralogy and Petrology. doi.10.1007/s00410-019-1612-4.
- Sizova, E., Hauzenberger, C., Fritz, H., Faryad, S.W. and Gerya, T. 2019. Late orogenic heating of (ultra)high pressure rocks: slab rollback vs. slab breakoff. Geosciences, 9(12), 499.
- Faryad, S. W., Jedlicka, R., Hauzenberger, C. Racek, M. 2018. High-pressure crystallization vs. recrystallization origin of garnet pyroxenite-eclogite within subduction related lithologies. Mineralogy and Petrology, 112, 603-616.
- Faryad, S.W, Kachlík, V ., Sláma J., Jedlicka, R. 2016. Coincidence of gabbro and granulite formation and their implication for Variscan HT metamorphism in the Moldanubian Zone (Bohemian Massif), example from the Kutná Hora Complex. Lithos 264, 56-69.
- Faryad, S.W., Žák, J. 2016. High-pressure granulites of the Podolsko complex, Bohemian Massif: An example of crustal rocks that were subducted to mantle depths and survived a pervasive mid-crustal high-temperature overprint. Lithos 246-247, 246-260.
Eclogites and ultrahigh-pressure rocks of the Bohemian Massif
Most eclogites and UHPM rocks, exposed in collision orogenies, reveal reequilibration in granulite or amphibolite facies conditions and their peak pressure or prograde minerals and textures are usually obliterated by low-pressure assemblages. Recent progress in micro- and nanoscale techniques allow to investigate solid- or fluid phase inclusions and reaction textures and to reconstruct the pre-amphibolite/granulite facies history of the rocks subjected to subduction or simply exhumed from the mantle depth. The Bohemian Massif is one of the best studied part of the Variscan Collision Orogeny, where lenses and boudins of eclogites and mantle peridotites are distributed in various lithotectonic units. UHP conditions were confirmed by index minerals only for some rocks, but mineral textures and thermobarometric calculations indicate that most of these rocks experienced subduction history. Our research group focuses on solid phase inclusions and their equilibrium products to trace the evidence of peak pressure history.
- Faryad, S. W., Jedlicka, R., Perraki, M., 2019. Apatite with lamellae of sulfide and other phases in UHP eclogites from Nové Dvory, Moldanubian Zone, Czech Republic; are they formed in open system? Mineralogical Magazine, 83-1, 95-105; 1-22. doi:10.1180/mgm.2018.146; IF = 1.744
- Faryad, S. W., Jedlicka, R., Hauzenberger, C., Racek, M., 2018. High-pressure crystallization vs. recrystallization origin of garnet pyroxenite-eclogite within subduction related lithologies. Mineralogy and Petrology, 112, 603-613; https://doi.org/10.1007/s00710-018-0557-z. IF = 1.236
- Jedlicka, R., Faryad, S. W., 2017. Felsic granulite with layers of eclogite facies rocks in the Bohemian Massif; did they share a common metamorphic history? Lithos, 286-287, 408-425. DOI: 10.1016/j.lithos.2017.06.027; IF = 3.677
- Faryad, S. W., Kachlík, V., Sláma, J., Jedlicka, R., 2016. Coincidence of gabbro and granulite formation and their implication for Variscan HT metamorphism in the Moldanubian Zone (Bohemian Massif), example from the Kutná Hora Complex, Lithos, 264, 56-69. DOI: 10.1016/j.lithos.2016.08.005; IF = 3.723
- Jedlicka, R., Faryad, S. W., Hauzenberger, C., 2015. Prograde metamorphic history of UHP granulites from the Moldanubian Zone (Bohemian Massif) revealed by major and Y+REEs zoning in garnets. Journal of Petrology, 56, 2069-2088. DOI: 10.1093/petrology/egv066; IF = 3.768
- Faryad, S.W. 2012. High-pressure polymetamorphic garnet growth in eclogites from the Mariánské Lázně Complex (Bohemian Massif). European Journal of Mineralogy, 24, 483–497.
- Faryad, S.W., 2011. Distribution and geological position of high-/ultrahigh-pressure units within the European Variscan Belt: a review, in: Dobrzhinetskaya, L., Faryad, S.W., Wallis, S., Cuthbert, S. (Eds.), Ultrahigh Pressure Metamorphism: 25 Years After the Discovery of Coesite and Diamond, Elsevier, p. 361–397.
- Faryad, S. W., Jedlička, R., Ettinger, K., 2013. Subduction of lithospheric upper mantle recorded by solid phase inclusions and compositional zoning in garnet: example from the Bohemian Massif. Gondwana Research, 23, 3, 944-955.
Petrological aspects related to partial melting of granitic rocks in (U)HP conditions
Study of high-grade metagranites of the Eger crystalline complex (border of the Saxothuringian and Teplá-Barrandian zones of the Bohemian Massif) revealed a record of prograde metamorphic conditions from middle crust to UHP conditions related to progressive partial melting and it has shown some important relations of recorded pressure with garnet minor elements content. The metamorphic fabric of the present lithologies is characterized by a presence of monomineralic banding of alternating Qtz, Ksp, Plg and Bt+Ms+Grt-rich bands, which gradually passes to fine grained homogeneous granofelse and felsic granulite characterized by phase mixing. The granofelses contain increased amount of white mica compared to the banded orthogness, while biotite content decreases. Granulites are composed of a "dry" mineral assemblage consisting of Ksp-Plg-Qtz-Grt-Ky. Petrological study shows record of an obvious increase in metamorphic grade indicated by: 1) increase of Si content in Ms connected with decrease of Bt content, 2) occurrence of Grt with high content of Na and P (up to 0.05 a.p.f.u.), 3) presence of coesite inclusions in high Na-P Grt. These changes are consistent with increase of P-T conditions from c. 680 °C and 10 kbar to c. 1000 °C and 30 kbar. Additionally, the observations confirm that the Na-P substitution may indicate (U)HP conditions.
- Závada P, Schulmann K, Racek M, Hasalová P, Jeřábek P, Weinberg RF, Štípská P, Roberts A (2018): Role of strain localization and melt flow on exhumation of deeply subducted continental crust. Lithosphere, 10 (2): 217-238, DOI: 10.1130/L666.1
Mass balance and major and trace element zoning in atoll garnet from eclogite facies rocks
Studied garnets come from samples of eclogite facies metamorphosed rocks from the central part of the Krušné hory Mountains (Saxothuringian Zone, Bohemian Massif). By using compositional mapping and profiles of garnets we distinguished two, older (I) and younger garnets (II), respectively. Garnet I, occurring in the core and at the mantle parts of grains, has higher contents of Ca and Mn and lower amounts of Mg and Fe than garnet II, which grows on the most rims of garnet or replaces garnet I in the central part. Grains with replaced core garnet I by other minerals form atoll texture. According to Faryad et al. (2010) the atoll garnets formed during fluid infiltration and element exchange between older garnets and matrix during prograde stage of eclogite facies metamorphism. To verify this idea, trace elements (especially Y and HREE), which have very low diffusion coefficients and they are highly compatible in garnet (Spear and Kohn, 1996; Carlson, et al. 2014) were analysed. Mass balance of Y+REE in garnet I and II was calculated for single garnet grains and for larger field of thin section containing high number of garnet grains to get representative contents related to percentual volume of garnet I and II. Calculated amount of released Y+REE (mainly Y+HREE) from dissolved garnet I corresponds with number of these elements in younger garnet II.
Record of metamorphic and metasomati processes at the contact of felsic and mafic rocks in HT conditions
Contact of felsic granulites with garnet pyroxenites is sometimes accompanied by occurence of mafic and intermediate granulites. The similarity of mafic granulites with garnet pyroxenites and felsic granulites with intermediate granulites in chemical composition, mineral assemblages and P-T evolution can signify, that mafic and intermediate granulites were derived from garnet pyroxenites and felsic granulites as a result of metasomatic processes at high tempereture conditions at the contact of chemically contrasting lithologies. Fluids incoming from felsic granulites can penetrate into garnet pyroxenites which is characterised by formation of K-rich net mostly along grain boundaries, specific symplectic texture formed of orthopyroxene and plagioclase coexisting with clinopyroxene and ingrowth of plagioclase into garnet mostly along garnet rims. In the second case fluids incoming from garnet pyroxenites could modify felsic granulites into intermediate granulites which is characterised by occurrence of orthopyroxene in matrix and kyanite breakdown to mixture of corundum and clinozoisite surrounded by garnet corona. Thermodynamical modelling shows that pyroxenites were isothermally decompressed from 25 kbars and 900 °C to 10 kbars. Felsic granulites were decompressed with temperature increase from 13–16 kbars and 800 °C to 10 kbars and 900–1000 °C.
The Jurassic Meliata Zone (Western Carpathians)
The Meliata unit with ophiolites and blueschist facies rocks occurs along southwards dipping tectonic zone between the Pannonian basin and the Western Carpathians. It was formed by closure of the Triassic Meliata-Hallstatt oceanic basin that related to the European Tethys. The blueschists form isolated slices overthrusting the basement units to the north and occur as tectonic blocks within very low-grade sedimentary sequences. The HP/LT rocks are represented by marbles with lenses and layers of metabasites and by phyllites. Tectonic slices of former amphibolite facies basement rocks, overprinted by blueschist facies metamorphism, are also present. The blueschist facies minerals in metabasites are glaucophane, epidote, albite, phengite and rarely paragonite, garnet and Na pyroxene with maximum 70 % jadeite component. Pelitic rocks may additionally contain chloritoid. Geochronological data indicates Middle Jurassic age for blueschit facies and Upper Jurassic for the very low-grade mélange matrix.
- Faryad, S.W. and Frank, W. 2011. Textural and age relations of polymetamorphic rocks in the HP Meliata Unit (Western Carpathians). Journal of Asian Earth Sciences, 42, 111-122
- Faryad, S.W. and Henjes-Kunst, F. (1997): K-Ar and Ar-Ar age constraints of the Meliata blueschist facies rocks, the Western Carpathians (Slovakia). Tectonophysics, 280, 141-156.
- Faryad, S.W (1995b): Phase petrology of mafic blueschists of the Meliata Unit (West Carpathians)-Slovakia. J. metamorphic Geol, 13, .432-448.
- Faryad, S.W. (1995a): Low-grade high-pressure metapelites and metapsammites of the Meliata Unit (West Carpathians) - Slovakia. Eur.J. Mineralogy, 7, 57-74.
Basement xenolites in metagranite from Panshir Valley (Western Hindu Kush)
The Western Hindu Kush refers to a ca 220 km long segment of nearly east–west trending high mountains which continue eastward through the Central and Eastern Hindu Kush to the Karakoram. It is bounded by Panjshir fault in the east and the Bamiyan–Shibar fault in the west. The rocks exposed on the surface are dominated by medium-grade Proterozoic and low-grade Early Paleozoic rocks that are intruded by granite–granodiorite plutons. Four different metamorphic events have been distinguished in the southern part of Western Hindu Kush. Based on an unconformity between basement units and Carboniferous cover sequences, the first two amphibolite and greenschist facies metamorphic events are Proterozoic and Pre-Carboniferous in age respectively. Third metamorphism was recognized in Triassic and Cretaceous granitic rocks in Panshir Valley near to contact with the Kabul Block. It is of Eocene age and reached medium pressure amphibolite facies conditions. The Fourth Metamorphism is of Eocene age and reached medium pressure amphibolite facies conditions. It is aimed to clear the origin of the xenolites and the effect of granite magma on their mineral formation. Preliminary textural relations indicate that the amphibolite facies metamorphism had minimum effect on mineral-textural changes.
- Faryad, S.W., Collett, S., Finger, F. Sergeev, S.Čopjaková, R., Siman, P. 2016. The Kabul Block (Afghanistan), a segment of the Columbia Supercontinent, with a Neoproterozoic metamorphic overprint. Gondwana Research, 34, 221-240.
- Collett, S. and Faryad, S.W. 2015. Pressure–temperature evolution of Neoproterozoic metamorphism in the Welayati Formation (Kabul Block), Afghanistan. Journal of Asian Earth Sciences, 111, 698-710.
- Collett, S., Faryad, S.W. Mosazai, A.M. 2015. Polymetamorphic evolution of the granulite-facies Paleoproterozoic basement of the Kabul Block, Afghanistan. Mineralogy and Petrology, 109, 463-484.
- Faryad, S.W., Collett, S. Petterson, M., Sergeev, S.V. 2013. Magmatism and metamorphism linked to the accretion of continental blocks south of the Hindu Kush, Afghanistan. Lithos, 175–176, 302–314.