@article{OberhaensliBousquetGoffe2003,
  author    = {Oberh{\"a}nsli, Roland and Bousquet, Romain and Goffe, B.},
  title     = {Comment to "Chloritoid composition and formation in the eastern Central Alps : a comparison between Penninic and Helvetic occurrences" by M. Rahn, M. Steinmann and M. Frey},
  issn      = {0036-7699},
  year      = {2003},
  language  = {en}
}
@article{MoazzenOberhaensliHajialioghlietal.2009,
  author    = {Moazzen, Mohssen and Oberh{\"a}nsli, Roland and Hajialioghli, Robab and Moeller, Andreas and Bousquet, Romain and Droop, Giles and Jahangiri, Ahmad},
  title     = {Peak and post-peak P-T conditions and fluid composition for scapolite-clinopyroxene-garnet calc-silicate rocks from the Takab area, NW Iran},
  issn      = {0935-1221},
  doi       = {10.1127/0935-1221/2009/0021-1887},
  year      = {2009},
  abstract  = {The Takab calcareous rocks of northwest Iran crop out in association with a variety of metamorphic rocks including mafic granulites, amphibolites, granitic gneisses, pelitic schists and meta-ultramafic rocks. They can be divided into marbles and calc-silicate rocks on the basis of the dominance of calcite/dolomite and silicate minerals. Dominant peak metamorphic granulite facies assemblage of calc-silicate rocks is Scp + Grt(I) + Cpx + Cal + Qtz +/- Hbl(I). The decrease of temperature and pressure during exhumation produced post-peak metamorphic assemblages. Coronal garnet (Grt II) in the calc-silicate rocks was produced by retrograde reactions consuming plagioclase and clinopyroxene, while peak metamorphic garnet (Grt I) occurs as preserved xenoblastic grains in calcite and/or plagioclase (Pl II). Regional metamorphism took place at 740 degrees C and X-CO2 similar to 0.9. Garnet-clinopyroxene-plagioclase-quartz (GADS) barometry yields a pressure of 8-9 kbar, corresponding to a depth of ca. 24-27 km. This was followed by decompression and hydration during exhumation of the crustal rocks up to the surface. Secondary phases such as garnet (II) hornblende (II), plagioclase (II), zoisite and titanite (II) constrain the temperature and pressure of post-peak metamorphism as similar to 600 degrees C and similar to 6 kbar respectively and a fluid with XCO2 as low as 0.4. Halogens were near-absent during the peak metamorphic stage. The scapolite and hornblende crystallized underpeak metamorphic conditions contain very low fluorine and chlorine, whereas relatively high fluorine (similar to 0.8 wt\%) in the titanite (II) and hornblende (II) suggests a possible infiltration of F-rich fluids into the calc-silicate rocks during retrogression. It is interpreted to be related to external fluids released during crystallisation of granitoid magmas and/or leucosome patches in the adjacent migmatites.},
  language  = {en}
}
@article{OberhaensliKoralayCandanetal.2013,
  author    = {Oberh{\"a}nsli, Roland and Koralay, E. and Candan, Osman and Pourteau, Amaury and Bousquet, Romain},
  title     = {Late cretaceous eclogitic high-pressure relics in the Bitlis Massif},
  series = {Geodinamica acta : revue de g{\´e}ologie dynamique et de g{\´e}ographie physique},
  volume    = {26},
  journal   = {Geodinamica acta : revue de g{\´e}ologie dynamique et de g{\´e}ographie physique},
  number    = {3-4},
  publisher = {Routledge, Taylor \& Francis Group},
  address   = {Abingdon},
  issn      = {0985-3111},
  doi       = {10.1080/09853111.2013.858951},
  pages     = {175 -- 190},
  year      = {2013},
  abstract  = {A new occurrence of eclogites was found in the Kesandere valley in the eastern most part of the Bitlis complex, SE Anatolia. These high-pressure (HP) relics were preserved in calc-arenitic metasediments within the high-grade metamorphic basement of the Bitlis complex. The eclogitic parageneses were strongly overprinted during decompression and heating. These new eclogites locality complements the evidence of blueschist-facies metamorphism documented recently in the meta-sedimentary cover sequence of this part of the Bitlis complex. Thermodynamic calculations suggest peak conditions of ca. 480-540 degrees C/1.9-2.4GPa. New U/Pb dates of 84.4 +/-.9 and 82.4 +/-.9Ma were obtained on zircons from two Kesandere eclogite samples. On the basis of geochemical criteria, these dates are interpreted to represent zircon crystallization during the eclogitic peak stage. Kesandere eclogites differ from those previously described in the western Bitlis complex (Mt. Gablor locality) in terms of lithologic association, protolithic origin, and peak P-T conditions (600-650 degrees C/1.0-2.0GPa, respectively). On the other hand, eclogitic metamorphism of Kesandere metasediments occurred shortly before blueschist-facies metamorphism of the sedimentary cover (79-74Ma Ar-40/Ar-39 white mica). Therefore, the exhumation of Kesandere eclogites started between ca. 82 and 79Ma, while the meta-sedimentary cover was being buried. During this short time span, Kesandere eclogite were likely uplifted from similar to 65 to 35km depth, indicating a syn-subduction exhumation rate of similar to 4.3mm/a. Subsequently, eclogite- and blueschist-facies rocks were likely retrogressed contemporarily during collision-type metamorphism (around 72-69Ma). The Bitlis HP rocks thus sample a subduction zone that separated the Bitlis-Puturge (Bistun?) block from the South-Armenian block, further north. To the south, Eocene metasediments of the Urse formation are imbricated below the Bitlis complex. They contain (post Eocene) blueschists, testifying separation from the Arabian plate and southward migration of the subduction zone. The HT overprint of Kesandere eclogites can be related to the asthenospheric flow provoked by subducting slab retreat or break off.},
  language  = {en}
}
@misc{OmraniMoazzenOberhaenslietal.2013,
  author    = {Omrani, H. and Moazzen, Mohssen and Oberh{\"a}nsli, Roland and Tsujimori, T. and Bousquet, Romain and Moayyed, M.},
  title     = {Metamorphic history of glaucophane-paragonite-zoisite eclogites from the Shanderman area, northern Iran},
  series = {Journal of metamorphic geology},
  volume    = {31},
  journal   = {Journal of metamorphic geology},
  number    = {8},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0263-4929},
  doi       = {10.1111/jmg.12045},
  pages     = {791 -- 812},
  year      = {2013},
  abstract  = {The Shanderman eclogites and related metamorphosed oceanic rocks mark the site of closure of the Palaeotethys ocean in northern Iran. The protolith of the eclogites was an oceanic tholeiitic basalt with MORB composition. Eclogite occurs within a serpentinite matrix, accompanied by mafic rocks resembling a dismembered ophiolite. The eclogitic mafic rocks record different stages of metamorphism during subduction and exhumation. Minerals formed during the prograde stages are preserved as inclusions in peak metamorphic garnet and omphacite. The rocks experienced blueschist facies metamorphism on their prograde path and were metamorphosed in eclogite facies at the peak of metamorphism. The peak metamorphic mineral paragenesis of the rocks is omphacite, garnet (pyrope-rich), glaucophane, paragonite, zoisite and rutile. Based on textural relations, post-peak stages can be divided into amphibolite and greenschist facies. Pressure and temperature estimates for eclogite facies minerals (peak of metamorphism) indicate 15-20kbar at similar to 600 degrees C. The pre-peak blueschist facies assemblage yields <11kbar and 400-460 degrees C. The average pressure and temperature of the post-peak amphibolite stage was 5-6kbar, similar to 470 degrees C. The Shanderman eclogites were formed by subduction of Palaeotethys oceanic crust to a depth of no more than 75km. Subduction was followed by collision between the Central Iran and Turan blocks, and then exhumation of the high pressure rocks in northern Iran.},
  language  = {en}
}
@article{JolivetGoffeBousquetetal.1998,
  author    = {Jolivet, L. and Goffe, B. and Bousquet, Romain and Oberh{\"a}nsli, Roland and Michard, Andre},
  title     = {Detachments in high-pressure mountain belts, Tethyan examples},
  year      = {1998},
  language  = {en}
}
@article{BousquetOberhaensli1997,
  author    = {Bousquet, Romain and Oberh{\"a}nsli, Roland},
  title     = {Distribution of HP-LT metamorphism and extensional deformation in the "B{\"u}ndnerschiefer" of the Engadine window (eastern Central Alps) : Implication of regional evolution},
  year      = {1997},
  language  = {en}
}
@article{OberhaensliGoffeBousquet1995,
  author    = {Oberh{\"a}nsli, Roland and Goffe, B. and Bousquet, Romain},
  title     = {Record of a HP-LT metamorphic evolution in the Valais zone : Geodynamics implications},
  issn      = {0392 - 758X},
  year      = {1995},
  language  = {en}
}
@article{BousquetOberhaensli1998,
  author    = {Bousquet, Romain and Oberh{\"a}nsli, Roland},
  title     = {High-pressure-low-temperature metamorphism and deformation in the "B{\"u}ndnerschiefer" of the Engadine window : implications for the regional evolution of the eastern Central Alps},
  year      = {1998},
  language  = {en}
}
@article{PourteauBousquetVidaletal.2014,
  author    = {Pourteau, Amaury and Bousquet, Romain and Vidal, Olivier and Plunder, Alexis and Duesterhoeft, Erik and Candan, Osman and Oberh{\"a}nsli, Roland},
  title     = {Multistage growth of Fe-Mg-carpholite and Fe-Mg-chloritoid, from field evidence to thermodynamic modelling},
  series = {Contributions to mineralogy and petrology},
  volume    = {168},
  journal   = {Contributions to mineralogy and petrology},
  number    = {6},
  publisher = {Springer},
  address   = {New York},
  issn      = {0010-7999},
  doi       = {10.1007/s00410-014-1090-7},
  pages     = {25},
  year      = {2014},
  abstract  = {We provide new insights into the prograde evolution of HP/LT metasedimentary rocks on the basis of detailed petrologic examination, element-partitioning analysis, and thermodynamic modelling of well-preserved Fe-Mg-carpholite- and Fe-Mg-chloritoid-bearing rocks from the Afyon Zone (Anatolia). We document continuous and discontinuous compositional (ferromagnesian substitution) zoning of carpholite (overall X-Mg = 0.27-0.73) and chloritoid (overall X-Mg = 0.07-0.30), as well as clear equilibrium and disequilibrium (i.e., reaction-related) textures involving carpholite and chloritoid, which consistently account for the consistent enrichment in Mg of both minerals through time, and the progressive replacement of carpholite by chloritoid. Mg/Fe distribution coefficients calculated between carpholite and chloritoid vary widely within samples (2.2-20.0). Among this range, only values of 7-11 correlate with equilibrium textures, in agreement with data from the literature. Equilibrium phase diagrams for metapelitic compositions are calculated using a newly modified thermodynamic dataset, including most recent data for carpholite, chloritoid, chlorite, and white mica, as well as further refinements for Fe-carpholite, and both chloritoid end-members, as required to reproduce accurately petrologic observations (phase relations, experimental constraints, Mg/Fe partitioning). Modelling reveals that Mg/Fe partitioning between carpholite and chloritoid is greatly sensitive to temperature and calls for a future evaluation of possible use as a thermometer. In addition, calculations show significant effective bulk composition changes during prograde metamorphism due to the fractionation of chloritoid formed at the expense of carpholite. We retrieve P-T conditions for several carpholite and chloritoid growth stages (1) during prograde stages using unfractionated, bulk-rock XRF analyses, and (2) at peak conditions using compositions fractionated for chloritoid. The P-T paths reconstructed for the Kutahya and Afyon areas shed light on contrasting temperature conditions for these areas during prograde and peak stages.},
  language  = {en}
}
@article{DuesterhoeftBousquetWichuraetal.2012,
  author    = {D{\"u}sterh{\"o}ft, Erik and Bousquet, Romain and Wichura, Henry and Oberh{\"a}nsli, Roland},
  title     = {Anorogenic plateau formation The importance of density changes in the lithosphere},
  series = {Journal of geophysical research : Solid earth},
  volume    = {117},
  journal   = {Journal of geophysical research : Solid earth},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {2169-9313},
  doi       = {10.1029/2011JB009007},
  pages     = {13},
  year      = {2012},
  abstract  = {Away from active plate boundaries the relationships between spatiotemporal variations in density and geothermal gradient are important for understanding the evolution of topography in continental interiors. In this context the classic concept of the continental lithosphere as comprising three static layers of different densities (upper crust, lower crust, and upper mantle) is not adequate to assess long-term changes in topography and relief in regions associated with pronounced thermal anomalies in the mantle. We have therefore developed a one-dimensional model, which is based on thermodynamic equilibrium assemblage computations and deliberately excludes the effects of melting processes like intrusion or extrusions. Our model calculates the "metamorphic density" of rocks as a function of pressure, temperature, and chemical composition. It not only provides a useful tool for quantifying the influence of petrologic characteristics on density, but also allows the modeled "metamorphic" density to be adjusted to variable geothermal gradients and applied to different geodynamic environments. We have used this model to simulate a scenario in which the lithosphere-asthenosphere boundary is subjected to continuous heating over a long period of time (130 Ma), and demonstrate how an anorogenic plateau with an elevation of 1400 m can be formed solely as a result of heat transfer within the continental lithosphere. Our results show that, beside dynamic topography (of asthenospheric origin), density changes within the lithosphere have an important impact on the evolution of anorogenic plateaus.},
  language  = {en}
}
@article{DuesterhoeftQuinterosOberhaenslietal.2014,
  author    = {Duesterhoeft, Erik and Quinteros, Javier and Oberh{\"a}nsli, Roland and Bousquet, Romain and de Capitani, Christian},
  title     = {Relative impact of mantle densification and eclogitization of slabs on subduction dynamics: A numerical thermodynamic/thermokinematic investigation of metamorphic density evolution},
  series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth},
  volume    = {637},
  journal   = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0040-1951},
  doi       = {10.1016/j.tecto.2014.09.009},
  pages     = {20 -- 29},
  year      = {2014},
  abstract  = {Understanding the relationships between density and spatio-thermal variations at convergent plate boundaries is important for deciphering the present-day dynamics and evolution of subduction zones. In particular, the interaction between densification due to mineralogical phase transitions and slab pull forces is subject to ongoing investigations. We have developed a two-dimensional subduction zone model that is based on thermodynamic equilibrium assemblage calculations and includes the effects of melting processes on the density distribution in the lithosphere. Our model calculates the "metamorphic density" of rocks as a function of pressure, temperature and chemical composition in a subduction zone down to 250 km. We have used this model to show how the hydration, dehydration, partial melting and fractionation processes of rocks all influence the metamorphic density and greatly depend on the temperature field within the subduction system. These processes are largely neglected by other approaches that reproduce the density distribution within this complex tectonic setting. Our model demonstrates that the initiation of edogitization (i.e., when crustal rocks reach higher densities than the ambient mantle) of the slab is not the only significant process that makes the descending slab denser and generates the slab pull force. Instead, the densification of the lithospheric mantle of the sinking slab starts earlier than eclogitization and contributes significantly to slab pull in the early stages of subduction. Accordingly, the complex metamorphic structure of the slab and the mantle wedge has an important impact on the development of subduction zones. (C) 2014 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{OberhaensliBousquetCandanetal.2012,
  author    = {Oberh{\"a}nsli, Roland and Bousquet, Romain and Candan, Osman and Okay, Aral I.},
  title     = {Dating subduction events in East Anatolia, Turkey},
  series = {Turkish journal of earth sciences = T{\"u}rk yerbilimleri dergisi},
  volume    = {21},
  journal   = {Turkish journal of earth sciences = T{\"u}rk yerbilimleri dergisi},
  number    = {1},
  publisher = {T{\"u}bitak},
  address   = {Ankara},
  issn      = {1300-0985},
  doi       = {10.3906/yer-1006-26},
  pages     = {1 -- 17},
  year      = {2012},
  abstract  = {Metamorphic studies in the cover sequences of the Bitlis complex allow the thermal evolution of the massif to be constrained using metamorphic index minerals. Regionally distributed metamorphic index minerals such as glaucophane, carpholite, relics of carpholite in chloritoid-bearing schists and pseudomorphs after aragonite in marbles record a LT-HP evolution:This demonstrates that the Bitlis complex was subducted and stacked to form a nappe complex during the closure of the Neo-Tethys. During late Cretaceous to Cenozoic evolution the Bitlis complex experienced peak metamorphism of 1.0-1.1 GPa at 350-400 degrees C. During the retrograde evolution temperatures remained below 460 degrees C. Ar-39/Ar-40 dating of white mica in different parageneses from the Bitlis complex reveals a 74-79 Ma (Campanian) date of peak metamorphism and rapid exhumation to an almost isothermal greenschist stage at 67-70 Ma (Maastrichtian). The HP Eocene flysch escaped the greenschist facies stage and were exhumed under very cold conditions. These single stage evolutions contrast with the multistage evolution reported further north from the Amassia-Stepanavan Suture in Armenia. Petrological investigations and isotopic dating show that the collision of Arabia with Eurasia resulted in an assemblage of different blocks derived from the northern as well as from the southern plate and a set of subduction zones producing HP rocks with diverse exhumation histories.},
  language  = {en}
}
@article{WichuraBousquetOberhaenslietal.2010,
  author    = {Wichura, Henry and Bousquet, Romain and Oberh{\"a}nsli, Roland and Strecker, Manfred and Trauth, Martin H.},
  title     = {Evidence for middleUocene uplift of the East African Plateau},
  issn      = {0091-7613},
  doi       = {10.1130/G31022.1},
  year      = {2010},
  abstract  = {Cenozoic uplift of the East African Plateau has been associated with fundamental climatic and environmental changes in East Africa and adjacent regions. While this influence is widely accepted, the timing and the magnitude of plateau uplift have remained unclear. This uncertainty stems from the lack of datable, geomorphically meaningful reference horizons that could record surface uplift. Here, we document the existence of significant relief along the East African Plateau prior to rifting, as inferred from modeling the emplacement history of one of the longest terrestrial lava flows, the similar to 300-km-long Yatta phonolite flow in Kenya. This 13.5 Ma lava flow originated on the present-day eastern Kenya Rift flank, and utilized a riverbed that once routed runoff from the eastern rim of the plateau. Combining an empirical viscosity model with subsequent cooling and using the Yatta lava flow geometry and underlying paleotopography (slope angle), we found that the prerift slope was at least 0.2 degrees, suggesting that the lava flow originated at a minimum elevation of 1400 m. Hence, high paleotopography in the Kenya Rift region must have existed by at least 13.5 Ma. We infer from this that middle Miocene uplift occurred, which coincides with the two-step expansion of grasslands, as well as important radiation and speciation events in tropical Africa.},
  language  = {en}
}