Journal ArticleDOI
Diamond and coesite discovered in Saxony-type granulite: Solution to the Variscan garnet peridotite enigma
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TLDR
Diamond and coesite were discovered in-situ as inclusions in garnet, kyanite and zircon in high-pressure granulites from the northern Bohemian Massif.Abstract:
Diamond and coesite were discovered in-situ as inclusions in
garnet, kyanite and zircon in high-pressure granulites from
northern Bohemian Massif. These continental crustal rocks were
therefore subducted to depths of c. 140 km, which also explains
their common association with mantle garnet-bearing
peridotites. Models involving crustal thickening for these
high-pressure granulites need to be significantly modified.
Whole Variscan belt with numerous HP granulite occurrences can
represent a large ultrahigh-pressure terrain.read more
Citations
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Journal ArticleDOI
Metamorphic chemical geodynamics in continental subduction zones
TL;DR: In this paper, a review of the geochemical properties of UHP terranes is presented, focusing on the following issues in continental subduction zones: the time and duration of uHP metamorphism, the origin and action of metamorphic fluid/melt inside UHP slices, the element and isotope mobilities under HP to UHP conditions during continental collision, the origins of premetamorphic protoliths and its bearing on continental collision types, and the crustal detachment and crust mantle interaction in subduction channels.
Book ChapterDOI
Orogenic, ophiolitic and abyssal peridotites
TL;DR: Orogenic, ophiolitic, and abyssal peridotites represent subcontinental, suboceanic, and subarc mantle rocks that were exhumed to the surface in various tectonic settings as mentioned in this paper.
Journal ArticleDOI
Two plates — Many subduction zones: The Variscan orogeny reconsidered
Uwe Kroner,Rolf L. Romer +1 more
TL;DR: In this paper, the authors explain the Variscan orogen in a two-plate scenario, reasoning that the complexity of the orogen (multitude of high-grade metamorphic belts, compositional diversity of coeval magmatism, and arrangement of foreland basins) is the result of the distribution of crustal domains of contrasting rheological properties.
Journal ArticleDOI
Pre-Mesozoic Alpine basements - Their place in the European Paleozoic framework
TL;DR: The Alpine orogenic structures shared a complex evolution, starting with Neoproterozoic sediments that are thought to have received detrital input from both West and East Gondwanan cratonic sources.
Journal ArticleDOI
Collision vs. subduction-related magmatism: two contrasting ways of granite formation and implications for crustal growth
Jean-François Moyen,Oscar Laurent,Oscar Laurent,Cyril Chelle-Michou,Simon Couzinié,Olivier Vanderhaeghe,Armin Zeh,Arnaud Villaros,Véronique Gardien +8 more
TL;DR: In this paper, the authors examined the granitic suites in a late-collision environment, the Variscan French Massif Central (FMC), and compared them with the suites found in an oceanic arc.
References
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Journal ArticleDOI
The equilibrium boundary between graphite and diamond
TL;DR: The equilibrium boundary between diamond and graphite has been determined over the temperature interval 1100°C-1625°C by using a piston-cylinder apparatus and a zero-friction cell as discussed by the authors.
Journal ArticleDOI
Raman Spectrum of Diamond
Stuart A. Solin,A. K. Ramdas +1 more
TL;DR: In this paper, the first and second-order Raman spectra of diamond were studied using the 4880 and 5145 lines of an Ar ion laser and the 6328 \AA{} line of a He-Ne laser.
Journal ArticleDOI
High‐pressure granulites: formation, recovery of peak conditions and implications for tectonics
Abstract: High-pressure granulites are characterised by the key associations garnet-clinopyroxene-plagioclase-quartz (in basic rocks) and kyanite-K-feldspar (metapelites and felsic rocks) and are typically orthopyroxene-free in both basic and felsic bulk compositions. In regional metamorphic areas, two essential varieties exist: a high- to ultrahigh-temperature group and a group representing overprinted eclogites. The high- to ultrahigh-temperature type formerly contained high-temperature ternary feldspar (now mesoperthite) coexisting with kyanite, is associated with garnet peridotites, and formed at conditions above 900 °C and 1.5 GPa. Clinopyroxene in subordinate basic rocks is Al-rich and textural evidence points to a high-pressure–high-temperature melting history. The second variety contains symplectite-like or poikilitic clinopyroxene-plagioclase intergrowths indicating former plagioclase-free, i.e. eclogite facies assemblages. This type of rock formed at conditions straddling the high-pressure amphibolite/high-pressure granulite field at around 700–850 °C, 1.0–1.4 GPa. Importantly, in the majority of high-pressure granulites, orthopyroxene is secondary and is a product of reactions at pressures lower than the peak recorded pressure. In contrast to low- and medium-pressure granulites, which form at conditions attainable in the mid to lower levels of normal continental crust, high-pressure granulites (of nonxenolith origin) mostly represent rocks formed as a result of short-lived tectonic events that led to crustal thickening or subduction of the crust into the mantle. Short times at high-temperature conditions are reflected in the preservation of prograde zoning in garnet and pyroxene. High-pressure granulites of both regional types, although rare, are known from both old and young metamorphic terranes (e.g. c. 45 Ma, Namche Barwa, E Himalaya; 400–340 Ma, European Variscides; 1.8 Ga Hengshan, China; 1.9 Ga, Snowbird, Saskatchewan and 2.5 Ga Jianping, China). This spread of ages supports proposals suggesting that thermal and tectonic processes in the lithosphere have not changed significantly since at least the end of the Archean.
Journal ArticleDOI
Ultrahigh-pressure minerals and metamorphic terranes – The view from China
TL;DR: For example, the very rare occurrence of microdiamond inclusions in zircons from Dabie-Sulu UHP rocks may reflect high f O 2 attending recrystallization inasmuch as epidote is rather common as mentioned in this paper.
Journal ArticleDOI
In-situ Raman spectroscopy of quartz: A pressure sensor for hydrothermal diamond-anvil cell experiments at elevated temperatures
TL;DR: In this article, changes in frequency and linewidth of the A1 Raman modes of quartz were determined over temperatures from 23 to 800 °C and simultaneously at pressures ranging between 0.1 MPa and 2.1 GPa using a hydrothermal diamond-anvil cell.