Research output: Contribution to journal › Article › peer-review
Forbidden mineral assemblage coesite-disordered graphite in diamond-bearing kyanite gneisses (Kokchetav Massif). / Shchepetova, Olga V.; Korsakov, Andrey; Mikhailenko, Denis et al.
In: Journal of Raman Spectroscopy, Vol. 48, No. 11, 01.11.2017, p. 1606-1612.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Forbidden mineral assemblage coesite-disordered graphite in diamond-bearing kyanite gneisses (Kokchetav Massif)
AU - Shchepetova, Olga V.
AU - Korsakov, Andrey
AU - Mikhailenko, Denis
AU - Zelenovskiy, Pavel
AU - Shur, Vladimir
AU - Ohfuji, Hiroaki
N1 - Publisher Copyright: Copyright © 2017 John Wiley & Sons, Ltd.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - Confocal 2D and 3D Raman imaging was applied to SiO2 inclusions in kyanite porphyroblasts from diamond-bearing kyanite gneisses of the Kokchetav Massif (Northern Kazakhstan). The study reveals a mineral assemblage of coesite-disordered graphite which is forbidden in ultrahigh pressure-high temperature (UHP-HT) metamorphic complexes. Disordered graphite in coesite inclusions is optically undetectable and has been identified exclusively by Raman spectroscopy. Raman imaging of the forbidden coesite-disordered graphite assemblage fails to detect bands assigned to fluid components (e.g. CO2, N2, CH4, H2Oliq), but the Raman spectra of fluid inclusions in kyanite, garnet and quartz demonstrate the presence of CO2, N2, CH4, H2Oliq and disordered graphite. The disordered graphite most likely formed by precipitation from a C―O―H fluid during the retrograde stage. The fluid was entrapped by kyanite with coesite inclusions near the peak metamorphic conditions. The lack of disordered graphite around diamond crystals in our samples does not support the generally accepted origin of disordered graphite in ultra high pressure metamorphic rocks by partial diamond graphitization during exhumation.
AB - Confocal 2D and 3D Raman imaging was applied to SiO2 inclusions in kyanite porphyroblasts from diamond-bearing kyanite gneisses of the Kokchetav Massif (Northern Kazakhstan). The study reveals a mineral assemblage of coesite-disordered graphite which is forbidden in ultrahigh pressure-high temperature (UHP-HT) metamorphic complexes. Disordered graphite in coesite inclusions is optically undetectable and has been identified exclusively by Raman spectroscopy. Raman imaging of the forbidden coesite-disordered graphite assemblage fails to detect bands assigned to fluid components (e.g. CO2, N2, CH4, H2Oliq), but the Raman spectra of fluid inclusions in kyanite, garnet and quartz demonstrate the presence of CO2, N2, CH4, H2Oliq and disordered graphite. The disordered graphite most likely formed by precipitation from a C―O―H fluid during the retrograde stage. The fluid was entrapped by kyanite with coesite inclusions near the peak metamorphic conditions. The lack of disordered graphite around diamond crystals in our samples does not support the generally accepted origin of disordered graphite in ultra high pressure metamorphic rocks by partial diamond graphitization during exhumation.
KW - coesite
KW - diamond
KW - disordered graphite
KW - Raman imaging
KW - UHP-HT metamorphism
KW - RAMAN-SPECTROSCOPY
KW - O-H FLUIDS
KW - NORTHERN-KAZAKSTAN
KW - CARBONACEOUS-MATERIAL
KW - CONTINENTAL-CRUST
KW - HIGH-TEMPERATURE CONDITIONS
KW - PRESSURE METAMORPHIC ROCKS
KW - SIBERIAN CRATON
KW - SPECTRA
KW - MANTLE ROCKS
UR - http://www.scopus.com/inward/record.url?scp=85019993776&partnerID=8YFLogxK
U2 - 10.1002/jrs.5167
DO - 10.1002/jrs.5167
M3 - Article
AN - SCOPUS:85019993776
VL - 48
SP - 1606
EP - 1612
JO - Journal of Raman Spectroscopy
JF - Journal of Raman Spectroscopy
SN - 0377-0486
IS - 11
ER -
ID: 9952773