V.M. Kvasnytsya, CRYSTAL MORPHOLOGY AND ORIGIN OF MICRODIAMONDS FROM NEOGENE SAMOTKAN PLACER (MIDDLE-DNIPRO AREA)

https://doi.org/10.15407/mineraljournal.42.01.012

UDC 549.211

CRYSTAL MORPHOLOGY AND ORIGIN OF MICRODIAMONDS FROM NEOGENE SAMOTKAN PLACER (MIDDLE-DNIPRO AREA)

V.MKvasnytsya, DrSc (Mineralogy and Crystallography), Prof., Head of Department. http://orcid.org/0000-0002-3692-7153
M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the NAS of Ukraine 34,
Acad. Palladin Ave., Kyiv, Ukraine, 03142
E-mail: vmkvas@hotmail.com

Language: Ukrainian
Mineralogical journal 2020, 42 (1): 12-23

Abstract: Using the methods of scanning electron microscopy and goniometry, the crystal morphology of microdiamonds from the Neogene Samotkan placer on the Middle Dnipro megablock of the Ukrainian Shield was studied. Crystal sizes do not exceed 0.3 mm in diameter. More than a hundred crystals are studied, selected from more than a thousandth collection. Crystal morphological features of microdiamonds are established. Among polyhedra of Samotkan microdiamonds, crystals with flat and smooth faces of various simple forms characteristic in the hexoctahedral symmetry class of diamond crystals (cube, rhombic dodecahedron, trigon- and tetragontrioctahedra, tetrahexahedra and hexoctahedra) are relatively common. Such forms are almost always incomplete and developed mainly on crystals of an octahedral habit. The diversity and dominance of cubic forms is a characteristic feature of Samotkan microdiamonds. As a rule, cubic crystals are complicated by the faces of the octahedron and rhombic dodecahedron (rounded dodecahedron). Two contrasting types of cubic crystals are distinguished by the mechanism of their formation — tangential in case of the degeneration of the (111) planes and normal (columnar) growth. Various twins and aggregates from cubes or octahedrons are another features of Samotkan microdiamonds. The twins of octahedrons and cubes after spinel law are widespread, as well as fivefold twins of octahedrons after spinel law and parallel crystal intergrowths occur. Crystallization of skeletal and vertex forms is also relatively often manifested on polyhedra. Octahedral crystals with signs of natural dissolution were found. Microtopography of the faces of various simple forms of polyhedra is common. In general, the crystallomorphological features of Samotkan microdiamonds indicate their crystallization in a carbon-saturated medium and also the rapid growth of crystals. The questions of the origin of Samotkan microdiamonds, their possible crystallization parental medium and their bedrock are considered. The mantle eclogite medium of diamond crystallization and the Early Proterozoic age of their primary sources are predicted.
Keywords: microdiamonds, crystal morphology, microtopography, microstructure, origin, Neogene Samotkan placer, the Ukrainian Shield.

References:

  1. Afanasyev, V.P., Efimova, E.S., Zinchuk, N.N. and Koptil, V.I. (2000), Atlas of the morphology of diamonds in Russia, Publ. House of the SB RAS, SIC OIGGM, Novosibirsk, RU, 294 p. [in Russian].
  2. Bartoshinsky, Z., Bekesha, S., Vinnichenko, T. and Poberezhska, I. (2003), Mineral. Review, Vol. 53, No. 1-2, Lviv, UA, pp. 15-34 [in Ukrainian].
  3. Bartoshinsky, Z.V. and Kvasnitsa, V.N. (1991), Crystallomorphology of diamond from kimberlites, Nauk. dumka, Kyiv, UA, 172 p. [in Russian].
  4. Zinchuk, N.N., Koptil, V.I. and Kvasnitsa, V.N. (2003), Mineral. Journ. (Ukraine), Vol. 25, No. 4, UA, pp. 32-47 [in Russian].
  5. Ilchenko, K.O., Kvasnytsya, V.M. and Taran, M.M. (2007), Proc. Ukr. Mineral. Soc., Vol. 4, UA, pp. 13-37 [in Ukrainian].
  6. Lavrova, L.D., Pechnikov, V.A., Pleshakov, A.M., Nadezhdina, E.D. and Shukolyukov, Yu.A. (1999), A new genetic type of diamond deposits, Scientific world press, Moscow, RU, 228 p. [in Russian].
  7. Orlov, Yu.L. (1963), Morphology of diamond, Gosgeoltekhizdat, Moscow, RU, 235 p. [in Russian].
  8. Orlov, Yu.L. (1973), Mineralogy of diamond, Nauka, Moscow, RU, 223 p. [in Russian].
  9. Polkanov, Yu.A. (1967), Rep. USSR Acad. Sci., Vol. 173, No. 4, RU, pp. 901-902 [in Russian].
  10. Polkanov, Yu.A. (2009), Fine diamonds of sand deposits: distribution, properties, origin, value, SPD Baranovsky A.E. press, Simferopol, UA, 228 p. [in Russian].
  11. Tarashchan, A.N. and Lupashko, T.N. (1999), Mineral. Journ. (Ukraine), Vol. 21, No. 2/3, UA, pp. 39-44 [in Russian].
  12. Fersman, A.E. (1955), Crystallography of Diamond, AS USSR, Moscow, RU, 566 p. [in Russian].
  13. Yurk, Yu.Yu., Kashkarov, I.F., Polkanov, Yu.A., Eremenko, G.K. and Yalovenko, I.P. (1973), Diamonds from sands of Ukraine, Nauk. dumka, Kyiv, UA, 167 p. [in Russian].
  14. Goldschmidt, V. (1916), Atlas der Krystallformen, C. Winters Universitatsbuchhandlung: Heidelberg, Band 3, tafel 17-48, text 37-51.
  15. Kvasnitsa, V.N., Zinchuk, N.N. and Koptil, V.I. (1999), Tipomorphizm of diamond microcrystals, Nedra, Moscow, RU, 224 p. [in English and Russian].
  16. Kvasnitsa, V.N., Silaev, V.I. and Smoleva, I.V. (2016), Geochem. Intern., Vol. 54, No. 11, RU, pp. 948-963. https://doi.org/10.1134/S0016702916090020
  17. Kvasnytsya, V.M. and Wirth, R. (2009), Lithos, Vol. 113, рр. 454-464. https://doi.org/10.1016/j.lithos.2009.05.019
  18. Vyshnevskyi, O.A. and Kvasnytsya, V.M. (2019), Abstracts of scientific conference "Achievements and prospects of development of geological science in Ukraine", devoted to the 50th anniversary of the Institute of Geochemistry, Mineralogy and Ore Formation of NAS of Ukraine, Vol. 1, Kyiv, UA, pp. 138-139.

PDF

English