Recycling of crustal materials through study of ultrahigh-pressure minerals in collisional orogens, ophiolites, and mantle xenoliths: A review

Liou, J. G.; Tsujimori, Tatsuki; Yang, Jingsui; Zhang, R.Y.; Ernst, W. G.

doi:10.1016/j.jseaes.2014.09.011

Cited by 75 publications

(35 citation statements)

References 297 publications

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“…Such diamond, first identified in crustal rocks from the Kokchetav Massif in northern Kazakhstan (Sobolev & Shatsky, 1990) and later at several localities worldwide (e.g. Gilotti, 2013;Liou et al, 2014), provides evidence for ultrahigh-pressure (UHP) metamorphism, together with other mineral indicators like coesite (Chopin, 1984;Smith, 1984). Crystallization from a supercritical C-O-H fluid or melt is generally accepted as a viable mechanism of metamorphic diamond formation (e.g.…”

Section: Introductionmentioning

confidence: 99%

Diamond in metasedimentary crustal rocks from Pohorje, Eastern Alps: a window to deep continental subduction

Janák

Froitzheim

Yoshida

et al. 2015

Journal Metamorphic Geology

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We report the first finding of diamond and moissanite in metasedimentary crustal rocks of Pohorje Mountains (Slovenia) in the Austroalpine ultrahigh‐pressure (UHP) metamorphic terrane of the Eastern Alps. Microscopic observations and Raman spectroscopy show that diamond occurs in situ as inclusions in garnet, being heterogeneously distributed. Under the optical microscope, diamond‐bearing inclusions are of cuboidal to rounded shape and of pinkish, yellow to brownish colour. The Raman spectra of the investigated diamond show a sharp, first order peak of sp3‐bonded carbon, in most cases centred between 1332 and 1330 cm−1, with a full width at half maximum between 3 and 5 cm−1. Several spectra show Raman bands typical for disordered graphitic (sp2‐bonded) carbon. Detailed observations show that diamond occurs either as a monomineralic, single‐crystal inclusion or it is associated with SiC (moissanite), CO2 and CH4 in polyphase inclusions. This rare record of diamond occurring with moissanite as fluid‐inclusion daughter minerals implies the crystallization of diamond and moissanite from a supercritical fluid at reducing conditions. Thermodynamic modelling suggests that diamond‐bearing gneisses attained P–T conditions of ≥3.5 GPa and 800–850 °C, similar to eclogites and garnet peridotites. We argue that diamond formed when carbonaceous sediment underwent UHP metamorphism at mantle depth exceeding 100 km during continental subduction in the Late Cretaceous (c. 95–92 Ma). The finding of diamond confirms UHP metamorphism in the Pohorje Mountains, the most deeply subducted part of Austroalpine units.

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Section: Introductionmentioning

confidence: 99%

Diamond in metasedimentary crustal rocks from Pohorje, Eastern Alps: a window to deep continental subduction

Janák

Froitzheim

Yoshida

et al. 2015

Journal Metamorphic Geology

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“…Consequently, ophiolitic peridotites and chromitites have been identified as a new and significant environment for natural diamond occurrence . Nevertheless, the source of carbon for ophiolite-hosted diamonds and the formation and the mode of integration of microdiamonds into ophiolitic chromitites are still not well known, and are debated (Liou et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Fourier transform infrared spectroscopy data and carbon isotope characteristics of the ophiolite-hosted diamonds from the Luobusa ophiolite, Tibet, and Ray-Iz ophiolite, Polar Urals

Cartigny

Yang

et al. 2017

Lithosphere

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We report new δ 13 C data and N content and aggregation state values for microdiamonds recovered from peridotites and chromitites of the Luobusa ophiolite (Tibet) and chromitites of the Ray-Iz ophiolite in the Polar Urals (Russia). All analyzed microdiamonds contain significant nitrogen contents (from 108 to 589 atomic ppm ± 20%) with a consistently low aggregation state and show identical infrared spectra dominated by strong absorption between 1130 cm -1 and 1344 cm -1 , and therefore characterize type Ib diamond. Microdiamonds from the Luobusa peridotites have δ 13 C (PDB) values ranging from −28.7‰ to −16.9‰, and N contents from 151 to 589 atomic ppm. The δ 13 C and N content values for diamonds from the Luobusa chromitites are −29‰ to −15.5‰ and 152-428 atomic ppm, respectively. Microdiamonds from the Ray-Iz chromitites show δ 13 C values varying from −27.6‰ to −21.6‰ and N contents from 108 to 499 atomic ppm. The carbon isotopes values have features similar to previously analyzed metamorphic diamonds from other worldwide localities, but the samples are characterized by lower N contents. In every respect, they are different from diamonds occurring in kimberlites and impact craters. Our samples also differ from the few synthetic diamonds we analyzed, in that they show enhanced δ 13 C variability and less advanced aggregation state than synthetic diamonds. Our newly obtained N aggregation state and N content data are consistent with diamond formation over a narrow and rather cold temperature range (i.e., <950 °C), and in a short residence time (i.e., within several million years) at high temperatures in the deep mantle.

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“…Among~25 coesite-bearing and~10 diamond-bearing localities discovered to date (e.g. Liou, Tsujimori, Yang, Zhang, & Ernst, 2014; their figure 3), the outcrops at Yangkou Bay in the Sulu belt of eastern China (Figures 1 and 2) represent the only example where intergranular coesite has been found in UHP eclogite of crustal origin. In addition, three grains of intergranular coesite have been found in an impure marble at Ganjialing in the Dabie Shan (Liu et al, 2017) and primary coesite occurs in a mantlederived xenolith of kyanite eclogite from the Roberts Victor kimberlite in South Africa (Smyth & Hatton, 1977).…”

Section: Introductionmentioning

confidence: 99%

On the survival of intergranular coesite inUHPeclogite

Wang

Brown

et al. 2017

Journal Metamorphic Geology

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Coesite is typically found as inclusions in rock‐forming or accessory minerals in ultrahigh‐pressure (UHP) metamorphic rocks. Thus, the survival of intergranular coesite in UHP eclogite at Yangkou Bay (Sulu belt, eastern China) is surprising and implies locally “dry” conditions throughout exhumation. The dominant structures in the eclogites at Yangkou are a strong D2 foliation associated with tight‐to‐isoclinal F2 folds that are overprinted by close‐to‐tight F3 folds. The coesite‐bearing eclogites occur as rootless intrafolial isoclinal F1 fold noses wrapped by a composite S1–S2 foliation in interlayered phengite‐bearing quartz‐rich schists. To evaluate controls on the survival of intergranular coesite, we determined the number density of intergranular coesite grains per cm2 in thin section in two samples of coesite eclogite (phengite absent) and three samples of phengite‐bearing coesite eclogite (2–3 vol.% phengite), and measured the amount of water in garnet and omphacite in these samples, and also in two samples of phengite‐bearing quartz eclogite (6–7 vol.% phengite, coesite absent). As coesite decreases in the mode, the amount of primary structural water stored in the whole rock, based on the nominally anhydrous minerals (NAMs), increases from 107/197 ppm H2O in the coesite eclogite to 157–253 ppm H2O in the phengite‐bearing coesite eclogite to 391/444 ppm H2O in the quartz eclogite. In addition, there is molecular water in the NAMs and modal water in phengite. If the primary concentrations reflect differences in water sequestered during the late prograde evolution, the amount of fluid stored in the NAMs at the metamorphic peak was higher outside of the F1 fold noses. During exhumation from UHP conditions, where NAMs became H2O saturated, dehydroxylation would have generated a free fluid phase. Interstitial fluid in a garnet–clinopyroxene matrix at UHP conditions has dihedral angles >60°, so at equilibrium fluid will be trapped in isolated pores. However, outside the F1 fold noses strong D2 deformation likely promoted interconnection of fluid and migration along the developing S2 foliation, enabling conversion of some or all of the intergranular coesite into quartz. By contrast, the eclogite forming the F1 fold noses behaved as independent rigid bodies within the composite S1–S2 foliation of the surrounding phengite‐bearing quartz‐rich schists. Primary structural water concentrations in the coesite eclogite are so low that H2O saturation of the NAMs is unlikely to have occurred. This inherited drier environment in the F1 fold noses was maintained during exhumation by deformation partitioning and strain localization in the schists, and the fold noses remained immune to grain‐scale fluid infiltration from outside allowing coesite to survive. The amount of inherited primary structural water and the effects of strain partitioning are important variables in the survival of coesite during exhumation of deeply subducted continental crust. Evidence of UHP metamorphism may be preserved in similar isolated st...

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Recycling of crustal materials through study of ultrahigh-pressure minerals in collisional orogens, ophiolites, and mantle xenoliths: A review

Cited by 75 publications

References 297 publications

Diamond in metasedimentary crustal rocks from Pohorje, Eastern Alps: a window to deep continental subduction

Diamond in metasedimentary crustal rocks from Pohorje, Eastern Alps: a window to deep continental subduction

Fourier transform infrared spectroscopy data and carbon isotope characteristics of the ophiolite-hosted diamonds from the Luobusa ophiolite, Tibet, and Ray-Iz ophiolite, Polar Urals

On the survival of intergranular coesite inUHPeclogite

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