@misc{BorghiniFerreroO'Brienetal.2019,
  author    = {Borghini, Alessia and Ferrero, Silvio and O'Brien, Patrick J. and Laurent, Oscar and G{\"u}nter, Christina and Ziemann, Martin Andreas},
  title     = {Cryptic metasomatic agent measured in situ in Variscan mantle rocks},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {976},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-47459},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-474592},
  pages     = {207 -- 234},
  year      = {2019},
  abstract  = {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 Klatschm{\"u}hle 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 (Star{\´e}, Česk{\´e} 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.},
  language  = {en}
}
@article{CarswellBruecknerCuthbertetal.2003,
  author    = {Carswell, D. A. and Brueckner, H. K. and Cuthbert, S. J. and Mehta, K. and O'Brien, Patrick J.},
  title     = {The timing of stabilisation and the exhumation rate for ultra-high pressure rocks in the Western Gneiss Region of Norway},
  year      = {2003},
  language  = {en}
}
@article{CarswellTuckerO'Brienetal.2003,
  author    = {Carswell, D. A. and Tucker, R. D. and O'Brien, Patrick J. and Krogh, T. E.},
  title     = {Coesite Micro-Inclusions and the U-Pb Age of Zircons from the Hareidland Eclogite in the Western Gneiss Region of Norway},
  year      = {2003},
  language  = {en}
}
@article{CookeO'Brien2001,
  author    = {Cooke, R. A. and O'Brien, Patrick J.},
  title     = {Resolving the relationship between high P-T rocks and gneisses in collisional terranes : an example from the Gf{\"o}hl gneiss-granulite association in the Moldanubian Zone, Austria},
  year      = {2001},
  language  = {en}
}
@article{CookeO'BrienCarswell2000,
  author    = {Cooke, R. A. and O'Brien, Patrick J. and Carswell, D. A.},
  title     = {Garnet zoning and the identification of equilibrium mineral compositions in high-pressure-temperature granulites from the Moldanubian Zone, Austria},
  year      = {2000},
  language  = {en}
}
@article{GuoO'BrienZhai2002,
  author    = {Guo, Jianbin H. and O'Brien, Patrick J. and Zhai, M. G.},
  title     = {High pressure granulites in the Sanggan area, North China craton : metamorphic evolution, P-T paths and geotectonic significance},
  year      = {2002},
  language  = {en}
}
@article{KonradSchmolkeHandyBabistetal.2005,
  author    = {Konrad-Schmolke, Matthias and Handy, Mark R. and Babist, Jochen and O'Brien, Patrick J.},
  title     = {Thermodynamic modelling of diffusion-controlled garnet growth},
  issn      = {0010-7999},
  year      = {2005},
  abstract  = {Numerical thermodynamic modelling of mineral composition and modes for specified pressure-temperature paths reveals the strong influence of fractional garnet crystallisation, as well as water fractionation, on garnet growth histories in high pressure rocks. Disequilibrium element incorporation in garnet due to the development of chemical inhomogeneities around porphyroblasts leads to pronounced episodic growth and may even cause growth interruptions. Discontinuous growth, together with pressure- and temperature-dependent changes in garnet chemistry, cause zonation patterns that are indicative of different degrees of disequilibrium element incorporation. Chemical inhomogeneities in the matrix surrounding garnet porphyroblasts strongly affect garnet growth and lead to compositional discontinuities and steep compositional gradients in the garnet zonation pattern. Further, intergranular diffusion-controlled calcium incorporation can lead to a characteristic rise in grossular and spessartine contents at lower metamorphic conditions. The observation that garnet zonation patterns diagnostic of large and small fractionation effects coexist within the same sample suggests that garnet growth is often controlled by small-scale variations in the bulk rock chemistry. Therefore, the spatial distribution of garnet grains and their zonation patterns, together with numerical growth models of garnet zonation patterns, yield information about the processes limiting garnet growth. These processes include intercrystalline element transport and dissolution of pre-existing grains. Discontinuities in garnet growth induced by limited element supply can mask traces of the thermobarometric history of the rock. Therefore, thermodynamic modelling that considers fractional disequilibrium crystallisation is required to interpret compositional garnet zonation in terms of a quantitative pressure and temperature path of the host rock},
  language  = {en}
}
@article{KonradSchmolkeO'BrienZack2011,
  author    = {Konrad-Schmolke, Matthias and O'Brien, Patrick J. and Zack, Thomas},
  title     = {Fluid Migration above a Subducted Slab-Constraints on Amount, Pathways and Major Element Mobility from Partially Overprinted Eclogite-facies Rocks (Sesia Zone, Western Alps)},
  series = {Journal of petrology},
  volume    = {52},
  journal   = {Journal of petrology},
  number    = {3},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0022-3530},
  doi       = {10.1093/petrology/egq087},
  pages     = {457 -- 486},
  year      = {2011},
  abstract  = {The Western Alpine Sesia-Lanzo Zone (SLZ) is a sliver of eclogite-facies continental crust exhumed from mantle depths in the hanging wall of a subducted oceanic slab. Eclogite-facies felsic and basic rocks sampled across the internal SLZ show different degrees of retrograde metamorphic overprint associated with fluid influx. The weakly deformed samples preserve relict eclogite-facies mineral assemblages that show partial fluid-induced compositional re-equilibration along grain boundaries, brittle fractures and other fluid pathways. Multiple fluid influx stages are indicated by replacement of primary omphacite by phengite, albitic plagioclase and epidote as well as partial re-equilibration and/or overgrowths in phengite and sodic amphibole, producing characteristic step-like compositional zoning patterns. The observed textures, together with the map-scale distribution of the samples, suggest open-system, pervasive and reactive fluid flux across large rock volumes above the subducted slab. Thermodynamic modelling indicates a minimum amount of fluid of 0 center dot 1-0 center dot 5 wt \% interacting with the wall-rocks. Phase relations and reaction textures indicate mobility of K, Ca, Fe and Mg, whereas Al is relatively immobile in these medium-temperature-high-pressure fluids. Furthermore, the thermodynamic models show that recycling of previously fractionated material, such as in the cores of garnet porphyroblasts, largely controls the compositional re-equilibration of the exhumed rock body.},
  language  = {en}
}
@article{KonradSchmolkeZackO'Brien2009,
  author    = {Konrad-Schmolke, Matthias and Zack, Thomas and O'Brien, Patrick J.},
  title     = {Combining thermodynamic and trace element modeling : a tool to quantify mineral reactions and trace element budgets during metamorphism},
  issn      = {0016-7037},
  doi       = {10.1016/j.gca.2009.05.009},
  year      = {2009},
  language  = {en}
}
@article{KonradSchmolkeZackO'Brienetal.2011,
  author    = {Konrad-Schmolke, Matthias and Zack, Thomas and O'Brien, Patrick J. and Barth, Matthias},
  title     = {Fluid migration above a subducted slab - Thermodynamic and trace element modelling of fluid-rock interaction in partially overprinted eclogite-facies rocks (Sesia Zone, Western Alps)},
  series = {Earth \& planetary science letters},
  volume    = {311},
  journal   = {Earth \& planetary science letters},
  number    = {3-4},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0012-821X},
  doi       = {10.1016/j.epsl.2011.09.025},
  pages     = {287 -- 298},
  year      = {2011},
  abstract  = {The amount and composition of subduction zone fluids and the effect of fluid-rock interaction at a slab-mantle interface have been constrained by thermodynamic and trace element modelling of partially overprinted blueschist-facies rocks from the Sesia Zone (Western Alps). Deformation-induced differences in fluid flux led to a partial preservation of pristine mineral cores in weakly deformed samples that were used to quantify Li, B, Stand Pb distribution during mineral growth, -breakdown and modification induced by fluid-rock interaction. Our results show that Li and 13 budgets are fluid-controlled, thus acting as tracers for fluid-rock interaction processes, whereas Stand Pb budgets are mainly controlled by the fluid-induced formation of epidote. Our calculations show that fluid-rock interaction caused significant Li and B depletion in the affected rocks due to leaching effects, which in turn can lead to a drastic enrichment of these elements in the percolating fluid. Depending on available fluid-mineral trace element distribution coefficients modelled fluid rock ratios were up to 0.06 in weakly deformed samples and at least 0.5 to 4 in shear zone mylonites. These amounts lead to time integrated fluid fluxes of up to 1.4-10(2) m(3) m(-2) in the weakly deformed rocks and 1-8-10(3) m(3) m(-2) in the mylonites. Combined thermodynamic and trace element models can be used to quantify metamorphic fluid fluxes and the associated element transfer in complex, reacting rock systems and help to better understand commonly observed fluid-induced trace element trends in rocks and minerals from different geodynamic environments.},
  language  = {en}
}