@article{AbdallaAdamAharonianetal.2020,
  author    = {Abdalla, H. and Adam, R. and Aharonian, Felix A. and Benkhali, F. Ait and Ang{\"u}ner, Ekrem Oǧuzhan and Arcaro, C. and Armand, C. and Armstrong, T. and Ashkar, H. and Backes, M. and Baghmanyan, V. and Martins, V. Barbosa and Barnacka, A. and Barnard, M. and Becherini, Y. and Berge, D. and Bernlohr, K. and Bi, B. and Bottcher, M. and Boisson, C. and Bolmont, J. and de Lavergne, M. de Bony and Bordas, Pol and Breuhaus, M. and Brun, F. and Brun, P. and Bryan, M. and Buchele, M. and Bulik, T. and Bylund, T. and Caroff, S. and Carosi, A. and Casanova, Sabrina and Chand, T. and Chandra, S. and Chen, A. and Cotter, G. and Curylo, M. and Mbarubucyeye, J. Damascene and Davids, I. D. and Davies, J. and Deil, C. and Devin, J. and deWilt, P. and Dirson, L. and Djannati-Atai, A. and Dmytriiev, A. and Donath, A. and Doroshenko, V. and Duffy, C. and Dyks, J. and Egberts, Kathrin and Eichhorn, F. and Einecke, S. and Emery, G. and Ernenwein, J. -P. and Feijen, K. and Fegan, S. and Fiasson, A. and de Clairfontaine, G. Fichet and Fontaine, G. and Funk, S. and Fussling, Matthias and Gabici, S. and Gallant, Y. A. and Giavitto, G. and Giunti, L. and Glawion, D. and Glicenstein, J. F. and Gottschall, D. and Grondin, M. -H. and Hahn, J. and Haupt, M. and Hermann, G. and Hinton, J. A. and Hofmann, W. and Hoischen, Clemens and Holch, T. L. and Holler, M. and Horbe, M. and Horns, D. and Huber, D. and Jamrozy, M. and Jankowsky, D. and Jankowsky, F. and Jardin-Blicq, A. and Joshi, V. and Jung-Richardt, I. and Kasai, E. and Kastendieck, M. A. and Katarzynski, K. and Katz, U. and Khangulyan, D. and Khelifi, B. and Klepser, S. and Kluzniak, W. and Komin, Nu. and Konno, R. and Kosack, K. and Kostunin, D. and Kreter, M. and Lamanna, G. and Lemiere, A. and Lemoine-Goumard, M. and Lenain, J. -P. and Levy, C. and Lohse, T. and Lypova, I. and Mackey, J. and Majumdar, J. and Malyshev, D. and Malyshev, D. and Marandon, V. and Marchegiani, P. and Marcowith, Alexandre and Mares, A. and Marti-Devesa, G. and Marx, R. and Maurin, G. and Meintjes, P. J. and Meyer, M. and Mitchell, A. and Moderski, R. and Mohamed, M. and Mohrmann, L. and Montanari, A. and Moore, C. and Morris, P. and Moulin, Emmanuel and Muller, J. and Murach, T. and Nakashima, K. and Nayerhoda, A. and de Naurois, M. and Ndiyavala, H. and Niederwanger, F. and Niemiec, J. and Oakes, L. and O'Brien, Patrick and Odaka, H. and Ohm, S. and Olivera-Nieto, L. and Wilhelmi, E. de Ona and Ostrowski, M. and Oya, I. and Panter, M. and Panny, S. and Parsons, R. D. and Peron, G. and Peyaud, B. and Piel, Q. and Pita, S. and Poireau, V. and Noel, A. Priyana and Prokhorov, D. A. and Prokoph, H. and Puhlhofer, G. and Punch, M. and Quirrenbach, A. and Raab, S. and Rauth, R. and Reichherzer, P. and Reimer, A. and Reimer, O. and Remy, Q. and Renaud, M. and Rieger, F. and Rinchiuso, L. and Romoli, C. and Rowell, G. and Rudak, B. and Ruiz-Velasco, E. and Sahakian, V. and Sailer, S. and Sanchez, D. A. and Santangelo, A. and Sasaki, M. and Scalici, M. and Schussler, F. and Schutte, H. M. and Schwanke, U. and Schwemmer, S. and Seglar-Arroyo, M. and Senniappan, M. and Seyffert, A. S. and Shafi, N. and Shiningayamwe, K. and Simoni, R. and Sinha, A. and Sol, H. and Specovius, A. and Spencer, S. and Spir-Jacob, M. and Stawarz, L. and Sun, L. and Steenkamp, R. and Stegmann, C. and Steinmassl, S. and Steppa, C. and Takahashi, T. and Tavernier, T. and Taylor, A. M. and Terrier, R. and Tiziani, D. and Tluczykont, M. and Tomankova, L. and Trichard, C. and Tsirou, M. and Tuffs, R. and Uchiyama, Y. and van der Walt, D. J. and van Eldik, C. and van Rensburg, C. and van Soelen, B. and Vasileiadis, G. and Veh, J. and Venter, C. and Vincent, P. and Vink, J. and Volk, H. J. and Vuillaume, T. and Wadiasingh, Z. and Wagner, S. J. and Watson, J. and Werner, F. and White, R. and Wierzcholska, A. and Wong, Yu Wun and Yusafzai, A. and Zacharias, M. and Zanin, R. and Zargaryan, D. and Zdziarski, A. A. and Zech, Alraune and Zhu, S. J. and Ziegler, A. and Zorn, J. and Zouari, S. and Zywucka, N.},
  title     = {An extreme particle accelerator in the Galactic plane},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {644},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {HESS Collaboration},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361/202038851},
  pages     = {8},
  year      = {2020},
  abstract  = {The unidentified very-high-energy (VHE; E > 0.1 TeV) gamma -ray source, HESS J1826-130, was discovered with the High Energy Stereoscopic System (HESS) in the Galactic plane. The analysis of 215 h of HESS data has revealed a steady gamma -ray flux from HESS J1826-130, which appears extended with a half-width of 0.21 degrees +/- 0.02 <br /> (stat)degrees <br /> stat degrees +/- 0.05 <br /> (sys)degrees sys degrees . The source spectrum is best fit with either a power-law function with a spectral index Gamma = 1.78 +/- 0.10(stat) +/- 0.20(sys) and an exponential cut-off at 15.2 <br /> (+5.5)(-3.2) -3.2+5.5 TeV, or a broken power-law with Gamma (1) = 1.96 +/- 0.06(stat) +/- 0.20(sys), Gamma (2) = 3.59 +/- 0.69(stat) +/- 0.20(sys) for energies below and above E-br = 11.2 +/- 2.7 TeV, respectively. The VHE flux from HESS J1826-130 is contaminated by the extended emission of the bright, nearby pulsar wind nebula, HESS J1825-137, particularly at the low end of the energy spectrum. Leptonic scenarios for the origin of HESS J1826-130 VHE emission related to PSR J1826-1256 are confronted by our spectral and morphological analysis. In a hadronic framework, taking into account the properties of dense gas regions surrounding HESS J1826-130, the source spectrum would imply an astrophysical object capable of accelerating the parent particle population up to greater than or similar to 200 TeV. Our results are also discussed in a multiwavelength context, accounting for both the presence of nearby supernova remnants, molecular clouds, and counterparts detected in radio, X-rays, and TeV energies.},
  language  = {en}
}
@article{KronerWildeO'Brienetal.2005,
  author    = {Kroner, Alfred and Wilde, S. A. and O'Brien, Patrick J. and Li, J. H. and Passchier, C. W. and Walte, N. P. and Liu, Dun Yi},
  title     = {Field relationships, geochemistry, zircon ages and evolution of a late Archaean to Palaeoproterozoic lower crustal section in the Hengshan Terrain of northern China},
  issn      = {1000-9515},
  year      = {2005},
  abstract  = {The Hengshan complex forms part of the central zone of the North China Craton and consists predominantly of ductilely-deformed late Archaean to Palaeoproterozoic high-grade, partly migmatitic, granitoid orthogneisses, intruded by mafic dykes of gabbroic composition. Many highly strained rocks were previously misinterpreted as supracrustal sequences and represent mylonitized granitoids and sheared dykes. Our single zircon dating documents magmatic granitoid emplacement ages between 2.52 Ga and 2.48 Ga, with rare occurrences of 2.7 Ga gneisses, possibly reflecting an older basement. A few granitic gneisses have emplacement ages between 2.35 and 2.1 Ga and show the same structural features as the older rocks, indicating that the main deformation occurred after similar to 2.1 Ga. Intrusion of gabbroic dykes occurred at similar to 1920 Ma, and all Hengshan rocks underwent granulite-facies metamorphism at 1.88-1.85 Ga, followed by retrogression, shearing and uplift. We interpret the Hengshan and adjacent Fuping granitoid gneisses as the lower, plutonic, part of a late Archaean to early Palaeoproterozoic Japan-type magmatic arc, with the upper, volcanic part represented by the nearby Wutai complex. Components of this arc may have evolved at a continental margin as indicated by the 2.7 Ga zircons. Major deformation and HP metamorphism occurred in the late Palaeoproterozoic during the Luliang orogeny when the Eastern and Western blocks of the North China Craton collided to form the Trans-North China orogen. Shear zones in the Hengshan are interpreted as major lower crustal discontinuities post-dating the peak of HP metamorphism, and we suggest that they formed during orogenic collapse and uplift of the Hengshan complex in the late Palaeoproterozoic (< 1.85 Ga)},
  language  = {en}
}
@article{O'BrienWalteLi2005,
  author    = {O'Brien, Patrick J. and Walte, N. P and Li, J. H.},
  title     = {The petrology of two distinct granulite types in the Hengshan Mts, China, and tectonic implications},
  issn      = {1367-9120},
  year      = {2005},
  abstract  = {The Archean to Proterozoic Hengshan Complex (North China Craton), comprises tonalitic and granodioritic gneisses with subordinate mafic lenses, pegmatites and granites. Amphibolite facies assemblages predominate, although granulite-facies relics are widespread, and greenschist-facies retrogression occurs in km-wide shear zones. Mafic lenses, locally abundant, occur as strongly deformed amphibolite (hornblende + plagioclase) boudins or sheets. In contrast to previously published models we find two series of mafic rocks with distinctly different granulite-facies evolutions. In the north of the complex, relict high-pressure mafic granulites are garnet + clinopyroxene-bearing rocks with a secondary development of orthopyroxene around both garnet (kelyphites) and clinopyroxene (coronas). South of the newly defined central, E-W-trending, Zhujiafang shear zone, numerous mafic boudins and less-deformed dykes exhibit a macroscopically visible magmatic texture with coronitic growth of metamorphic garnet (full of quartz inclusions) between the magmatic plagioclase and pyroxene domains. Additional orthopyroxene (after magmatic augite) and sodic rims to magmatic plagioclase clearly indicate medium-pressure granulite-facies metamorphism. These findings suggest tectonic juxtaposition in this area of three different structural levels of the same Proterozoic-imprinted crust: high-pressure granulite grade in the northern Hengshan, medium-pressure granulite grade in the southern Hengshan and amphibolite- to greenschist-facies grade in the Wutaishan to the SE. (c) 2004 Elsevier Ltd. All rights reserved},
  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{TreloarO'BrienParrishetal.2003,
  author    = {Treloar, P. J. and O'Brien, Patrick J. and Parrish, R. R. and Khan, M. A.},
  title     = {Exhumation of early Tertiary, coesite-bearing eclogites from the Pakistan Himalaya},
  year      = {2003},
  language  = {en}
}
@article{LiKroenerQianetal.2000,
  author    = {Li, J. H. and Kr{\"o}ner, Alfred and Qian, X. L. and O'Brien, Patrick J.},
  title     = {Tectonic evolution of an early Precambrian high-pressure granulite belt in the North China Craton},
  year      = {2000},
  language  = {en}
}
@article{O'Brien2006,
  author    = {O'Brien, Patrick J.},
  title     = {The age of deep, steep continental subduction in the NW Himalaya : relating zircon growth to metamorphic history. Comment on: "The onset of India-Asia continental collision: Early, steep subduction required by the timing of UHP metamorphism in the western Himalaya" by Mary L. Leech, S. Singh, A.K. Jain, Simon L. Klemperer and R.M. Manickavasagam, Earth and Planetary Science Letters 234 (2005) 83-97},
  doi       = {10.1016/j.epsl.2006.03.033},
  year      = {2006},
  abstract  = {Leech et al. [Mary L. Leech, S. Singh, A.K. Jain, Simon L. Klemperer and R.M. Manickavasagam, Earth and Planetary Science Letters 234 (2005) 83-97], present 3 clusters of ages for growth stages in zircon from quartzo- feldspathic gneisses hosting coesite-bearing eclogite from the Tso Morari Complex, NW India. These age clusters, from oldest to youngest, are interpreted to represent the age of ultrahigh-pressure metamorphism, a subsequent eclogite facies overprint and a later amphibolite facies retrogression and require subduction of Indian crust to have started earlier than previously accepted. However, no petrographic evidence, such as inclusions in the zircons relating to particular metamorphic events, is presented to substantiate the proposed sequence of metamorphic stages. Previously published data from eclogites of the same area indicate that coesite-eclogite is not the first but at least the second eclogite facies stage. In addition, the newly proposed time interval between coesite-eclogite and the amphibolite facies overprint is longer than previously indicated by diffusion modelling of natural garnet-garnet couples in eclogite. Neither the age of ultrahigh-pressure metamorphism nor the timing of initiation of subduction is reliably constrained by the presented data},
  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{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{MoellerO'BrienKennedyetal.2003,
  author    = {M{\"o}ller, Andreas and O'Brien, Patrick J. and Kennedy, Allen and Kr{\"o}ner, Alfred},
  title     = {Linking growth episodes of zircon and metamorphic textures to zircon chemistry : an example from the ultra-high temperature granulites of Rogaland (SW 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{MassonneO'Brien2003,
  author    = {Massonne, Hans-Joachim and O'Brien, Patrick J.},
  title     = {The Bohemian Massif and the NW Himalayas},
  year      = {2003},
  language  = {en}
}
@article{MoellerO'BrienKennedyetal.2002,
  author    = {M{\"o}ller, Andreas and O'Brien, Patrick J. and Kennedy, Allen and Kr{\"o}ner, Alfred},
  title     = {Polyphase zircon in ultrahigh-temperature granulites (Rogaland, SW Norway) : constraints for Pb diffusion in zircon},
  year      = {2002},
  abstract  = {SHRIMP U-Pb ages have been obtained for zircon in granitic gneisses from the aureole of the Rogaland anorthosite-norite intrusive complex, both from the ultrahigh temperature (UHT; >900 °C pigeonite-in) zone and from outside the hypersthene-in isograd. Magmatic and metamorphic segments of composite zircon were characterised on the basis of electron backscattered electron and cathodoluminescence images plus trace element analysis. A sample from outside the UHT zone has magmatic cores with an age of 1034 ± 7 Ma (2{sigma}, n = 8) and 1052 ± 5 Ma (1{sigma}, n = 1) overgrown by M1 metamorphic rims giving ages between 1020 ± 7 and 1007 ± 5 Ma.In contrast, samples from the UHT zone exhibit four major age groups:(1) magmatic cores yielding ages over 1500 Ma(2) magmatic cores giving ages of 1034 ± 13 Ma (2{sigma}, n = 4) and 1056 ± 10 Ma (1{sigma}, n = 1)(3) metamorphic overgrowths ranging in age between 1017 ± 6 Ma and 992 ± 7 Ma (1{sigma}) corresponding to the regional M1 Sveconorwegian granulite facies metamorphism, and(4) overgrowths corresponding to M2 UHT contact metamorphism giving values of 922 ± 14 Ma (2{sigma}, n = 6). Recrystallized areas in zircon from both areas define a further age group at 974 ± 13 Ma (2{sigma}, n = 4).This study presents the first evidence from Rogaland for new growth of zircon resulting from UHT contact metamorphism. More importantly, it shows the survival of magmatic and regional metamorphic zircon relics in rocks that experienced a thermal overprint of c. 950 °C for at least 1 Myr. Magmatic and different metamorphic zones in the same zircon are sharply bounded and preserve original crystallization age information, a result inconsistent with some experimental data on Pb diffusion in zircon which predict measurable Pb diffusion under such conditions. The implication is that resetting of zircon ages by diffusion during M2 was negligible in these dry granulite facies rocks. Imaging and Th/U-Y systematics indicate that the main processes affecting zircon were dissolution-reprecipitation in a closed system and solid-state recrystallization during and soon after M1.},
  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{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{O'BrienZotovLawetal.2001,
  author    = {O'Brien, Patrick J. and Zotov, Nikolay and Law, Robin and Khan, M. Azam and Jan, M. Q.},
  title     = {Coesite in Himalayan eclogite and implications for models of India-Asia collision},
  issn      = {0091-7613},
  year      = {2001},
  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{O'Brien2000,
  author    = {O'Brien, Patrick J.},
  title     = {The fundamental Variscan problem : high-temperature metamorphism at different depths and high-pressure metamorphism at different temperatures},
  year      = {2000},
  language  = {en}
}
@article{KroenerWildeZhaoetal.2006,
  author    = {Kr{\"o}ner, Alfred and Wilde, Simon A. and Zhao, Guochun and O'Brien, Patrick J. and Sun, Min and Liu, Dun Yi and Wan, Yusheng and Liu, S. W. and Guo, Jianbin H.},
  title     = {Zircon geochronology and metamorphic evolution of mafic dykes in the Hengshan Complex of northern China: Evidence for late Palaeoproterozoic extension and subsequent high-pressure metamorphism in the North China Craton},
  issn      = {0301-9268},
  doi       = {10.1016/j.precamres.2006.01.008},
  year      = {2006},
  abstract  = {Magmatic and metamorphic zircons have been dated from ductilely deformed gabbroic dykes defining a dyke swarm and signifying crustal extension in the northern part of the Hengshan Complex of the North China Craton, These dykes now occur as boudins and deformed sheets within migmatitic tonalitic, trondhjemitic, granodioritic and granitic gneisses and are conspicuous due to relics of high-pressure granulite or even former eclogite facies garnet + pyroxene-bearing assemblages. SHRIMP ages for magmatic zircons from two dykes reflect the time of dyke emplacement at similar to 1915 Ma, whereas metamorphic zircons dated by both SHRIMP and evaporation techniques are consistently in the range 1848-1888 Ma. The Youngest granitoid gneiss yet dated in the Hengshan has an emplacement age of 18 2 17 Ma. These results complement recent geochronological studies from the neighbouring Wutai and Fuping Complexes, to the SE of the Hengshan, showing that a crustal extension event Occurred in the late Palaeoproterozoic. This preceded a major high-pressure collision- type metamorphic event in the central part of the North China Craton that occurred in the Palaeoproterozoic and not in the late Archaean as previously thought. Our data support recent suggestions that the North China Craton experienced a major, craton-wide orogenic event in the late Palaeoproterozoic after which it became cratonized and acted as a stable block.},
  language  = {en}
}
@article{O'Brien2006,
  author    = {O'Brien, Patrick J.},
  title     = {Type-locality granulites: high-pressure rocks formed at eclogite-facies conditions},
  doi       = {10.1007/s00710-005-0108-2},
  year      = {2006},
  abstract  = {The type-locality granulites from the Granulitgebirge of Saxony, Germany, are rocks of broadly granitic composition containing minor garnet and kyanite within a commonly mylonitised matrix of feldspars and quartz. Petrographic evidence indicates a primary assemblage of ternary feldspar + quartz + garnet + kyanite + rutile, most likely resulting from partial melting of a granitic protolith, for which equilibrium temperature and pressure conditions of > 1000 degrees C and > 1.5 GPa have been deduced. These extreme (for crustal rocks) conditions, and the inferred peak assemblage, are supported by the newly-developed Zr-in-rutile geothermometer and experimental studies on the same bulk composition, respectively. As these conditions lie above those required for plagioclase stability in quartz tholeiites, they are thus in the eclogite facies. Widespread modification of the peak assemblage, for example mesoperthite formation after ternary feldspar, deformation-induced recrystallisation of perthites to two-feldspar + quartz aggregates, biotite replacing garnet, Ca-loss at garnet rims, sillimanite replacing kyanite or secondary garnet growth, makes reliable interpretation of equilibrium assemblages and compositions very difficult and explains the spread of published pressure- temperature values and consequent confusion about formation depths and the validity of tectonometamorphic models. Such extreme metamorphic conditions in rock compositions typical for the upper continental crust, reflecting a hot subduction environment, has important consequences for understanding some collisional orogens},
  language  = {en}
}
@article{KroenerO'BrienNemchinetal.2000,
  author    = {Kr{\"o}ner, Alfred and O'Brien, Patrick J. and Nemchin, A. A. and Pidgeon, R. T.},
  title     = {Zircon ages for high pressure granulites from South Bohemia, Czech Republic, and their connection to Carboniferous high temperature processes},
  year      = {2000},
  language  = {en}
}
@article{O'Brien2001,
  author    = {O'Brien, Patrick J.},
  title     = {Subduction followed by Collision : Alpine and Himalayan examples},
  year      = {2001},
  language  = {en}
}
@article{O'BrienKryza2001,
  author    = {O'Brien, Patrick J. and Kryza, R.},
  title     = {The Variscan basement of the Polish Sudetes},
  year      = {2001},
  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'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}
}
@article{SchmidtMezgerO'Brien2011,
  author    = {Schmidt, Alexander and Mezger, Klaus and O'Brien, Patrick J.},
  title     = {The time of eclogite formation in the ultrahigh pressure rocks of the Sulu terrane Constraints from Lu-Hf garnet geochronology},
  series = {Lithos : an international journal of mineralogy, petrology, and geochemistry},
  volume    = {125},
  journal   = {Lithos : an international journal of mineralogy, petrology, and geochemistry},
  number    = {1-2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0024-4937},
  doi       = {10.1016/j.lithos.2011.04.004},
  pages     = {743 -- 756},
  year      = {2011},
  abstract  = {Eclogites from the main borehole of the Chinese Continental Scientific Drilling project yield highly precise Lu-Hf garnet-clinopyroxene ages of 216.9 +/- 1.2 Ma (four samples) and 220.5 +/- 2.7 Ma (one sample). The spatial distribution of the rare earth elements in garnet is consistent with the preservation of primary growth zoning, unmodified by diffusion, which supports the interpretation that the Lu-Hf ages date the time of formation of garnet, the major rock forming mineral in the eclogites. The preservation of primary REE-zoning, despite peak metamorphic temperatures around 800-850 degrees C. indicates that the Lu-Hf chronometer is perfectly suitable to date garnet-forming reactions in high grade rocks. The range of Lu-Hf ages for eclogites in the Dabie-Sulu UHP terrane point to episodic rather than continuous growth of garnets and thus punctuated metamorphism during the collision of the North China Block and the Yangtze Block. The U-Pb ages and Hf-isotope systematics of zircon grains from one eclogite sample imply a protracted geologic history of the eclogite precursors that started around 2 Ga and culminated in the UHP metamorphism around 220 Ma.},
  language  = {en}
}
@article{KotkovaO'BrienZiemann2011,
  author    = {Kotkova, Jana and O'Brien, Patrick J. and Ziemann, Martin Andreas},
  title     = {Diamond and coesite discovered in Saxony-type granulite solution to the Variscan garnet peridotite enigma},
  series = {Geology},
  volume    = {39},
  journal   = {Geology},
  number    = {7},
  publisher = {American Institute of Physics},
  address   = {Boulder},
  issn      = {0091-7613},
  doi       = {10.1130/G31971.1},
  pages     = {667 -- 670},
  year      = {2011},
  abstract  = {The pressures required for diamond and coesite formation far exceed conditions reached by even the deepest present-day orogenic crustal roots. Therefore the occurrence of metamorphosed continental crust containing these minerals requires processes other than crustal thickening to have operated in the past. Here we report the first in situ finding of diamond and coesite, characterized by micro-Raman spectroscopy, in high-pressure granulites otherwise indistinguishable from granulites found associated with garnet peridotite throughout the European Variscides. Our discovery confirms the provenance of Europe's first reliable diamond, the "Bohemian diamond," found in A.D. 1870, and also represents the first robust evidence for ultrahigh-pressure conditions in a major Variscan crustal rock type. A process of deep continental subduction is required to explain the metamorphic pressures and the granulite-garnet peridotite association, and thus tectonometamorphic models for these rocks involving a deep orogenic crustal root need to be significantly modified.},
  language  = {en}
}
@article{KonradSchmolkeBabistHandyetal.2006,
  author    = {Konrad-Schmolke, Matthias and Babist, Jochen and Handy, Mark R. and O'brien, Patrick J.},
  title     = {The physico-chemical properties of a subducted slab from garnet zonation patterns (Sesia Zone, Western Alps)},
  series = {Journal of petrology},
  volume    = {47},
  journal   = {Journal of petrology},
  number    = {11},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0022-3530},
  doi       = {10.1093/petrology/egl039},
  pages     = {2123 -- 2148},
  year      = {2006},
  abstract  = {Garnets in continentally derived high-pressure (HP) rocks of the Sesia Zone (Western Alps) exhibit three different chemical zonation patterns, depending on sample locality. Comparison of observed garnet zonation patterns with thermodynamically modelled patterns shows that the different patterns are caused by differences in the water content of the subducted protoliths during prograde metamorphism. Zonation patterns of garnets in water-saturated host rocks show typical prograde chemical zonations with steadily increasing pyrope content and increasing XMg, together with bell-shaped spessartine patterns. In contrast, garnets in water-undersaturated rocks have more complex zonation patterns with a characteristic decrease in pyrope and XMg between core and inner rim. In some cases, garnets show an abrupt compositional change in core-to-rim profiles, possibly due to water-undersaturation prior to HP metamorphism. Garnets from both water-saturated and water-undersaturated rocks show signs of intervening growth interruptions and core resorption. This growth interruption results from bulk-rock depletion caused by fractional garnet crystallization. The water content during burial influences significantly the physical properties of the subducted rocks. Due to enhanced garnet crystallization, water-undersaturated rocks, i.e. those lacking a free fluid phase, become denser than their water-saturated equivalents, facilitating the subduction of continental material. Although water-bearing phases such as phengite and epidote are stable up to eclogite-facies conditions in these rocks, dehydration reactions during subduction are lacking in water-undersaturated rocks up to the transition to the eclogite facies, due to the thermodynamic stability of such hydrous phases at high P-T conditions. Our calculations show that garnet zonation patterns strongly depend on the mineral parageneses stable during garnet growth and that certain co-genetic mineral assemblages cause distinct garnet zonation patterns. This observation enables interpretation of complex garnet growth zonation patterns in terms of garnet-forming reactions and water content during HP metamorphism, as well determination of detailed P-T paths.},
  language  = {en}
}
@article{WilkeO'BrienAltenbergeretal.2010,
  author    = {Wilke, Franziska Daniela Helena and O'Brien, Patrick J. and Altenberger, Uwe and Konrad-Schmolke, Matthias and Khan, M. Ahmed},
  title     = {Multi-stage reaction history in different eclogite types from the Pakistan Himalaya and implications for exhumation processes},
  issn      = {0024-4937},
  doi       = {10.1016/j.lithos.2009.07.015},
  year      = {2010},
  abstract  = {Metabasites were sampled from rock series of the subducted margin of the Indian Plate, the so-called Higher Himalayan Crystalline, in the Upper Kaghan Valley, Pakistan. These vary from corona dolerites, cropping out around Saif- ul-Muluk in the south, to coesite-eclogite close to the suture zone against rocks of the Kohistan arc in the north. Bulk rock major- and trace-element chemistry reveals essentially a single protolith as the source for five different eclogite types, which differ in fabric, modal mineralogy as well as in mineral chemistry. The study of newly-collected samples reveals coesite (confirmed by in situ Raman spectroscopy) in both garnet and omphacite. All eclogites show growth of amphiboles during exhumation. Within some coesite-bearing eclogites the presence of glaucophane cores to barroisite is noted whereas in most samples porphyroblastic sodic-calcic amphiboles are rimmed by more aluminous calcic amphibole (pargasite, tschermakite, and edenite). Eclogite facies rutile is replaced by ilmenite which itself is commonly surrounded by titanite. In addition, some eclogite bodies show leucocratic segregations containing phengite, quartz, zoisite and/or kyanite. The important implication is that the complex exhumation path shows stages of initial cooling during decompression (formation of glaucophane) followed by reheating: a very similar situation to that reported for the coesite-bearing eclogite series of the Tso Morari massif, India, 450 km to the south-east.},
  language  = {en}
}
@article{O'BrienRoetzler2003,
  author    = {O'Brien, Patrick J. and R{\"o}tzler, Jochen},
  title     = {High-Pressure Granulites : Formation, Recovery of Peak Conditions, and Implications for Tectonics},
  year      = {2003},
  language  = {en}
}
@article{ScottKonradSchmolkeO'Brienetal.2013,
  author    = {Scott, James M. and Konrad-Schmolke, Matthias and O'Brien, Patrick J. and G{\"u}nter, Christina},
  title     = {High-T, low-P formation of rare olivine-bearing symplectites in variscan eclogite},
  series = {Journal of petrology},
  volume    = {54},
  journal   = {Journal of petrology},
  number    = {7},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0022-3530},
  doi       = {10.1093/petrology/egt015},
  pages     = {1375 -- 1398},
  year      = {2013},
  abstract  = {Extremely rare veinlets and reaction textures composed of symplectites of olivine (similar to Fo(43-55)) + plagioclase +/- spinel +/- ilmenite, associated with more common pyroxene + plagioclase and amphibole + plagioclase varieties, are preserved within eclogites and garnet pyroxenites in the Moldanubian Zone of the Bohemian Massif. Thermodynamic modelling integrated with conventional geothermometry conducted on an eclogite reveals that the symplectite-forming stage occurred at high T (similar to 850 degrees C) and low P (< 6 and > 2 center dot 5 kbar). The development of the different symplectite types reflects reactions that took place in micro-scale domains. The breakdown of high-P garnet controlled the formation of olivine-bearing and amphibole + plagioclase symplectites, whereas breakdown of high-P omphacite led to formation of pyroxene + plagioclase symplectites. In addition, post-eclogite facies but pre-symplectite stage porphyroblastic amphibole and phlogopite were also replaced by olivine-bearing symplectites. Material transfer calculations and thermodynamic modelling indicate that the formation of different symplectite types was linked despite their different bulk compositions. For example, the olivine-bearing symplectites gained Fe +/- Mg, whereas adjacent amphibole + plagioclase and pyroxene + plagioclase symplectites show losses in Fe and Mg; Al, Si and Ca were also variably exchanged. The olivine-bearing symplectites were particularly sensitive to Na despite the small concentration of this element. In eclogites where Na was readily available, the plagioclase composition in the olivine-bearing symplectites shifted from pure anorthite to bytownite, with the less calcic feldspar partitioning Si and inhibiting the formation of orthopyroxene. This regional high-T, low-P granulite-facies symplectite overprint may have been caused by advective heat loss from rapidly exhumed high-T, high-P granulitic bodies (Gfohl Unit) that were emplaced into and over the middle crust (Monotonous and Varied Series) during Carboniferous continent-continent collision.},
  language  = {en}
}
@article{WilkeO'BrienGerdesetal.2010,
  author    = {Wilke, Franziska Daniela Helena and O'Brien, Patrick J. and Gerdes, Axel and Timmerman, Martin Jan and Sudo, Masafumi and Khan, M. Ahmed},
  title     = {The multistage exhumation history of the Kaghan Valley UHP series, NW Himalaya, Pakistan from U-Pb and Ar-40/Ar- 39 ages},
  issn      = {0935-1221},
  doi       = {10.1127/0935-1221/2010/0022-2051},
  year      = {2010},
  abstract  = {Amphibole and mica Ar-40/Ar-39 ages as well as zircon, rutile and titanite U-Pb geochronology of eclogites and associated host rocks from the Higher Himalayan Crystalline Nappes (Indian Plate) in the Upper Kaghan Valley, Pakistan allow distinction of a multistage exhumation history. An Eocene age for peak-pressure metamorphism has been obtained by phengite Ar-40/Ar-39 (47.3 +/- 0.3 Ma) and zircon U-Pb (47.3 +/- 0.4 and 47.4 +/- 0.3 Ma) ages from cover and basement gneisses. A very short-lived metamorphic peak and rapid cooling is documented by an amphibole Ar-40/Ar-39 age of 46.6 +/- 0.5 Ma and a rutile U-Pb age of 44.1 +/- 1.3 Ma from eclogites. Phengite and biotite ages from cover and basement sequences metamorphosed during the Himalayan orogeny are 34.5 +/- 0.2 to 28.1 +/- 0.2 Ma whereas youngest biotites, yielding 23.6 +/- 0.1 and 21.7 +/- 0.2 Ma, probably reflect argon partial resetting. The amphibole age, together with those derived from phengite and zircon demonstrate a rate of initial exhumation of 86-143 mm/a i.e. an extremely rapid transport of the Indian Plate continental crust from ultra-high pressure (UHP) conditions back to crustal levels (47-46 Ma for transport from 140 to 40 km depth). Subsequent exhumation (46-41 Ma, 40-35 km) slowed to about 1 mm/a at the base of the continental crust but increased again later towards slightly higher exhumation rates of ca. 2 mm/a (41-34 Ma, 35- 20 km). This indicates a change from buoyancy-driven exhumation at mantle depths to compression forces related to continent-continent collision and accompanied crustal folding, thrusting and stacking that finally exposed the former deeply-buried rocks.},
  language  = {en}
}
@article{WilkeSobelO'Brienetal.2012,
  author    = {Wilke, Franziska Daniela Helena and Sobel, Edward and O'Brien, Patrick J. and Stockli, Daniel F.},
  title     = {Apatite fission track and (U-Th)/He ages from the Higher Himalayan Crystallines, Kaghan Valley, Pakistan: Implications for an Eocene Plateau and Oligocene to Pliocene exhumation},
  series = {Journal of Asian earth sciences},
  volume    = {59},
  journal   = {Journal of Asian earth sciences},
  number    = {3},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {1367-9120},
  doi       = {10.1016/j.jseaes.2012.06.014},
  pages     = {14 -- 23},
  year      = {2012},
  abstract  = {Apatite fission track and apatite and zircon (U-Th)/He ages were obtained from high- and ultra high-pressure rocks from the Kaghan Valley, Pakistan. Four samples from the high altitude northern parts of the valley yielded apatite fission track ages between 24.5 +/- 3.7 and 15.6 +/- 2.1 Ma and apatite (U-Th)/He ages between 21.0 +/- 0.6 and 5.3 +/- 0.2 Ma. These data record cooling of the formerly deeply-subducted high-grade metamorphic rocks induced by denudation and exhumation consistent with extension and back sliding along the reactivated, normal-acting Main Mantle Thrust. Overlap at around 10 Ma between fission track and (U-Th)/He ages is recognised at one location (Besal) showing that fast cooling occurred due to brittle reactivation of a former thrust fault. Widespread Miocene cooling is also evident in adjacent areas to the west (Deosai Plateau, Tso Moran), most likely related to uplift and unroofing linked to continued underplating of the Indian lower crust beneath Ladakh and Kohistan in the Late Eocene to Oligocene. In the southernmost part of the study area, near Naran, two significantly younger Late Miocene to Pliocene apatite fission track ages of 7.6 +/- 2.1 to 4.0 +/- 0.5 Ma suggest a spatial and temporal separation of exhumation processes. These younger ages are best explained by enhanced Late Miocene uplift and erosion driven by thrusting along the Main Boundary Thrust.},
  language  = {en}
}
@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{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},
  volume    = {38},
  publisher = {Wiley-Blackwell},
  address   = {Oxford [u.a.]},
  issn      = {1525-1314},
  doi       = {10.1111/jmg.12519},
  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}
}