@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{OhuchiNishiharaKawazoeetal.2012,
  author    = {Ohuchi, Tomohiro and Nishihara, Yu and Kawazoe, Takaaki and Spengler, Dirk and Shiraishi, Rei and Suzuki, Akio and Kikegawa, Takumi and Ohtani, Eiji},
  title     = {Superplasticity in hydrous melt-bearing dunite Implications for shear localization in Earth's upper mantle},
  series = {Earth \& planetary science letters},
  volume    = {335},
  journal   = {Earth \& planetary science letters},
  number    = {12},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0012-821X},
  doi       = {10.1016/j.epsl.2012.04.032},
  pages     = {59 -- 71},
  year      = {2012},
  abstract  = {Deformation experiments on hydrous melt-bearing dunite (olivine+4 vol\% orthopyroxene+4 vol\% clinopyroxene with less than 2.5 vol\% of the melt phase) were conducted at pressures of 1.3-5.7 GPa and temperatures of 1270-1490 K in order to explore the effect of intergranular fluids on the plastic flow of olivine in Earth's upper mantle. The strain rate was proportional to steady-state creep strength to the 2.1 power, and the creep strength markedly increased with increase in grain size. Developments of the crystallographic preferred orientation of olivine and flattening of olivine grains were hardly observed even after 33-55\% shortening of the samples. These observations show that grain boundary sliding (GBS) dominated the deformation of olivine (i.e., superplasticity). The creep strength of hydrous melt-bearing dunite was 2-5 times lower than that of melt-free dunite. The dependence of creep rate on melt fraction is known to be expressed empirically as (epsilon) over dot(phi) = (epsilon) over dot(0) exp(alpha phi), where alpha is a constant and phi is the melt fraction. The experimentally obtained value of alpha was in the range of 150-230, corresponding to 5-7 times the reported values for the olivine-basalt system at 0.3 GPa (i.e., creep strength of dunite was efficiently reduced by the hydrous melt). Superplasticity is the dominant creep mechanism of olivine in fluid-bearing fine-grained peridotites under low-temperature and high-stress conditions (i.e., peridotite shear zones in the upper mantle). Superplasticity induced by geological fluids would play an important role in the shear localization (and thus initiation of subduction) in the upper mantle.},
  language  = {en}
}
@article{NishiharaOhuchiKawazoeetal.2014,
  author    = {Nishihara, Yu and Ohuchi, Tomohiro and Kawazoe, Takaaki and Spengler, Dirk and Tasaka, Miki and Kikegawa, Takumi and Suzuki, Akio and Ohtani, Eiji},
  title     = {Rheology of fine-grained forsterite aggregate at deep upper mantle conditions},
  series = {Journal of geophysical research : Solid earth},
  volume    = {119},
  journal   = {Journal of geophysical research : Solid earth},
  number    = {1},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {2169-9313},
  doi       = {10.1002/2013JB010473},
  pages     = {253 -- 273},
  year      = {2014},
  language  = {en}
}