The mechanism of disordered graphite formation in uph diamond-bearing complexes

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Abstract

Kyanite gneiss from the "New Barchinsky" locality (Kokchetav Massif) was studied in detail. This rock is characterized by zonal distribution of the C and SiO2 polymorphs in kyanite porphyroblasts: (1) porphyroblast cores with graphite and quartz inclusions; (2) clean overgrowth zone with inclusions of cuboctahedral diamond crystals. The Raman mapping of SiO2 polymorphs originally showed the presence of an association of disordered graphite + coesite “prohibited” in HT diamond-bearing rocks. Graphitization of diamond is the only likely mechanism of the disordered graphite formation in HT diamond-bearing rocks. However, the absence of disordered graphite in association with diamond in kyanite porphyroblasts from kyanite gneiss from the "New Barchinsky" locality eliminates the process of diamond graphitization at the retrograde stage. Most likely, crystallization of disordered graphite occurred at the retrograde stage from the UHP C-O-H fluid.

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O. V. Shchepetova

Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences

Author for correspondence.
Email: olgashchepetova@igm.nsc.ru
Russian Federation, 3, Koptyug prospect, Novosibirsk, 630090

A. V. Korsakova

Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences

Email: olgashchepetova@igm.nsc.ru
Russian Federation, 3, Koptyug prospect, Novosibirsk, 630090

P. S. Zelenovskiy

Ural Federal University

Email: olgashchepetova@igm.nsc.ru
Russian Federation, 51, Lenina ave., Ekaterinburg, 620000

D. S. Mikhailenko

Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences

Email: olgashchepetova@igm.nsc.ru
Russian Federation, 3, Koptyug prospect, Novosibirsk, 630090

References

  1. Schertl H.P., Sobolev N.V. // J. Asian Earth Sci. 2013. V. 63. P. 5–38.
  2. Beyssac O., Goffé B., Chopin C., Rouzaud J. N. // Contribs Mineral. and Petrol. 2002. V. 143. №. 1. P. 19–31.
  3. Luque F.J., Pasteris J.D., Wopenka B., Rodas M., Barrenechea J.F. // Amer. J. Sci. 1998. V. 298. P. 471–498.
  4. Sokol A.G., Palyanova G.A., Palyanov Y.N., Tomi­len­ko A.A., Melenevsky V.N. // Geochim. et Cos-mo­chim. Acta. 2009. V. 73. №. 19. P. 5820–5834.
  5. Wopenka B., Pasteris J.D. // Amer. Mineral. 1993. V. 78. № 5/6. P. 533–557.
  6. Sobolev N.V., Shatsky V.S. // Nature. 1990. V. 343. №. 6260. P. 742–746.
  7. Добрецов Н.Л., Буслов М.М., Жимулев Ф.И., Тра­вин А. В., Заячковский А. А. // Геология и геофизика. 2006. Т. 47. № 4. С. 428–444.
  8. Korsakov A.V., Shatsky V.S., Sobolev N.V., Zayachokovsky A. A. // Eur. J. Mineral. 2002. V. 14. № 5. P. 915–928.
  9. Hermann J. // Lithos. 2003. V. 70. №. 3. P. 163–182.
  10. Tomkins H.S., Powell R., Ellis D.J. // J. Metamorp. Geol. 2007. V. 25. №. 6. P. 703–713.
  11. Stepanov A.S., Rubatto D., Hermann J., Kor­sakov A.V. // Amer. Mineral. 2016. V. 101. № 4. P. 788–807.
  12. Green T.H., Hellman P.L. // Lithos. 1982. V. 15. № 4. P. 253–266.
  13. Hemley R.J. // High-Pressure Res. Mineral. Phys.: a Volume in Honor of Syun-iti Akimoto. Tokyo, 1987. P. 347–359.
  14. Perrillat J.P., Daniel I., Lardeaux J. M., Cardon H. // J. Petrol. 2003. V. 44. №. 4. P. 773–788.
  15. Hwang S.L., Shen P., Chu H.T., Yui T.F., Liou J.G., Sobolev N.V., Shatsky V.S. // Earth and Planet. Sci. Lett. 2005. V. 231. №. 3. P. 295–306.

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2. Fig. 1. a - Sample of kyanite gneiss with large porphyroblasts of kyanite and garnet (“New Barchinsky” section, Kokchetav massif). (b) Porphyroblast kyanite with a zonal distribution of polymorphic modifications of carbon and SiO2 from kyanite gneisses of the “New Barchinsky” site.

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3. Fig. 2. a - Overview photo of kyanite porphyroblast from kyanite gneisses of the “New Barchinsky” site. b, c - Enlarged areas of the photo a: b - cubooctahedral diamond crystals, c - a graphite-rich core containing inclusions represented by coesite and disordered graphite. (d) Representative KR-spectra of inclusions of diamond (dashed line) and coesite (solid line), identified in the graphite-rich core of the kyanite porphyroblast.

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4. Fig. 3. a - Photo of intergrowth of coesite with optically indiscernible graphite. b - CF map of the investigated inclusion of coesite with disordered graphite. c, d - Individual Raman spectra of the phases identified in the inclusion of coesite with disordered graphite.

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