Agates of Onega structure Paleoproterozoic volcanic rocks (Central Karelia)

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Abstract

Agate mineralization in Central Karelia (the North-West Russia) is associated with the Paleoproterozoic volcanic rocks of the Ludicovian system (2.05—1.95 Ga) in the Onega structure. Agates and parent volcanic rocks were studied by optical and electron microscopy, electron microprobe and X-ray diffraction analyses, Raman spectroscopy, ICP-MS. It is shown that the main role in the agates structure has silica minerals: fine-grained quartz, fibrous and fine-flaked chalcedony. Agates are characterized by inclusions of coarse-crystalline calcite, microinclusions of chlorite, iron oxides and hydroxides, hydroxylapatite, epidote, mica (phengite), apatite, pyrite, chalcopyrite, titanite, leucoxene. Presence of contrasting rhythms in agates are marked by a change in composition of impurity mineral phases and different microtexture of silica layers represented by different-grained aggregates of quartz, fine flaked and fibrous chalcedony, quartzin. This indicates a stage-by-stage crystallization process with different temperature and pressure conditions of agate formation, which may also reflect the heterogeneity of the initial hydrothermal fluid. High concentrations of Ti, Cr, Mn, Ni, Cu (10—120 ppm) and low concentrations of Li, Co, Ga, Zn, Sr, Zr, Mo, Sn (0.5—10 ppm) have been found characteristic for quartz-chalcedony agates. Calcite in agates is characterized by high concentrations of Mn (1253—6675 ppm), Sс, Ti, Ni, Sr, Y, La, Ce, Nd (5—56 ppm). The chondrite-normalized REE distribution in agates shows a decay profile from La to Lu and a negative Eu anomaly in some samples. Low contents of rare metals and REE in agates, in comparison with parent volcanic rock, indicates a gradual chemical depletion of circulating fluids at the agate formation stage.

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Evgeniya Nikolaevna Svetova

Karelian Research Center of the Russian Academy of Sciences

Author for correspondence.
Email: enkotova@rambler.ru
ORCID iD: 0000-0003-2346-1777
SPIN-code: 1674-3314

PhD, senior reseach of mineral ores department

Russian Federation, Pushkinskaya st., 11, Petrozavodsk, Russia, 185910

Sergey Anatolievich Svetov

Karelian Research Center of the Russian Academy of Sciences

Email: Ssvetov@krc.karelia.ru

Doctor of science, director of the Institute of geology of Karelian research center

Russian Federation, Pushkinskaya st., 11, Petrozavodsk, Russia, 185910

References

  1. Barsanov G. P., Yakovleva M. E. Mineralogy of ornamental and semi-precious varieties of the fine-grained silica. Мoscow: Nauka, 1984. 144 p. (in Russian).
  2. Denniston R. F., Shearer C. K., Layne G. D., Vaniman D. T. SIMS analyses of minor and trace element distributions in fracture calcite from Yucca mountain, Nevada, USA. Geochim. Cosmochim. Acta. 1997. Vol. 61. N 9. P. 1803-1818.
  3. Geptner A. R. Hydrothermal mineralization in the Iceland rift zone (tectonic control of the formation of mineral concentrations). Lithol. Miner. Res. 2009. Vol. 44. N 3. P. 205-228 (in Russian).
  4. Godovikov A. A., Ripinen O. I., Motori S. G. Agates. Moscow: Nedra, 1987. 368 p. (in Russian).
  5. Goncharov V. I., Gorodinsky M. E., Pavlov G. F., Savva N. E., Fadeev A. P., Vorzepnev V. V., Gunchenko E. V. Chalcedony of the northeast USSR. Moscow: Nauka, 1987. 191 p. (in Russian).
  6. Gotze J., Tichomirowa M., Fuchs H., Pilot J., Sharp Z. D. Geochemistry of agates: a trace element and stable isotope study. Chem. Geol. 2001. Vol. 175. P. 523-541.
  7. Kukuy A. L., Atabaev K. K., Matveeva O. P. Crystal morphology, composition and properties of Iceland spar from Siberian platform. Prospect Protection Miner. Res. 2009. N 3. P. 32-38 (in Russian).
  8. Martin A. P., Prave A. R., Condon D. J., Lepland A., Fallick A. E., Romashkin A. E., Medvedev P. V., Rychanchik D. V. Multiple Palaeoproterozoic carbon burial episodes and excursions. Earth Planet. Sci. Lett. 2015. Vol. 424. P. 226-236.
  9. Mockel R., Götze J., Sergeev S. A., Kapitonov I. N., Adamskaya E. V., Goltsin N. A., Vennemann T. Trace-element analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS): a Case study for agates from Nowy Kościoł, Poland. J. Siberian Federal Univers. Engineer. Technol. 2012. Vol. 5. N 1. С. 3-18.
  10. Möller P. Rare earth elements and yttrium fractionation caused by fluid migration. J. Czech Geol. Soc. 1997. Vol. 42. P. 43.
  11. Paleoproterozoic Onega structure (geology, tectonics, deep structure, and mineralogeny). Ed. by L. V. Glushanin, V. N. Sharov, V. V. Shchiptsov. Petrozavodsk: KSC RAS, 2011. 431 p. (in Russian).
  12. Polehovsky Y. S., Punin Yu. O. Agate mineralization in basaltoids of the northeastern Ladoga region, South Karelia. Geol. Ore Deposits. 2008. Vol. 50. N 7. P. 642-646.
  13. Puchtel I. S., Bogatikov O. A., Kulikov V. S., Kulikova V. V., Zhuravlev D. Z. The role of crustal and mantle sources in the petrogenesis of continental magmatism: evidence from isotope and geochemica study of the Early Proterozoic picrites from the Onega plateau, Baltic shield. Petrology. 1995. Vol. 3. P. 397-419 (in Russian).
  14. Sun S. S., McDonough W. F. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. In: Magmatism in the OceanBasins. Saunders A. D., Norry M. J. (eds) Geol. Soc. Spec. Publ. 1989. N 42. P. 313-345.
  15. Svetov A. P. Platform basaltic volcanism of Karelian Karelides. Leningrad: Nauka, 1979. 208 p. (in Russian).
  16. Svetov S. A. Contamination as a initialization factor of liquid immiscibility in basaltic melts. Lithosfera. 2013. N 2. P. 3-19 (in Russian).
  17. Svetov S. A., Stepanova A. V., Chazhengina S. Y., Svetova E. N., Rybnikova Z. P., Mikhailova A. I., Paramonov A. S., Utitsyna V. L., Ekhova M. V., Kolodey B. S. Precision geochemical (ICP-MS, LA-ICP-MS) analysis of rock and mineral composition: the method and accuracy estimation in the case study of early precambrian mafic complexes. Proc. KSC RAS, 2015. N 7. P. 54-73 (in Russian).
  18. Timofeev V. M. Chalcedony of Sujsar Island. Proc. Soc. St. Petersburg Natural. 1912. Vol. 35. N 5. P. 157-174 (in Russian).
  19. Timofeev V. M. On the genesis of Onega shungite. Proc. Soc. Leningrad Natural. 1924. Vol. 39. N 4 P. 99-122 (in Russian).

Supplementary files

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2. Fig. 1. Geographic position and location of agate occurrences in the Onega Lake basin (Onezhskaya.., 2011).

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3. Fig. 2. Agates of the Onega structure in Central Karelia: their zonal-concentrical (quartz-chalcedony), vaguely-picture-like, spotted, mossy and other varieties.

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4. Fig. 3. Photomicrographs of thin sections of agate from volcanites of Onega structure in Central Karelia.

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5. Fig. 4 Electron microscope images of the sculpture of quartz-chalcedony agate chips (Pinʼguba occurrence in Onega structure).

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6. Fig. 5. Electron microscope images of microinclusions in agates from Onega structure in Central Karelia.

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7. Fig. 6. Raman spectra of mineral phases in agates from Onega structure (Central Karelia): 1 — quartz, 2 — chlorite, 3 — hematite, 4 — albite, 5 — calcite, 6 — goethite; 7 — carbon-bearing inclusion.

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8. Fig. 7. Distribution of rare and rare-earth elements in agates and host volcanic rocks of the Onega structure in Central Karelia; normalized to the primitive mantle according to (Sun, McDonough, 1989).

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9. Fig. 8. Chondrite-normalized (Sun, McDonough, 1989) distribution of REE in agates and host volcanites of the Onega structure.

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