Vostochno-Verkhotursky gabbro-diorite-granodiorite massif (Middle Urals): new data on composition, formation conditions, age and metallogeny

A. V. Korovko, M. D. Vishnyakova, N. S. Borodina, M. V. Zaitseva, V. V. Parphenov 

A. V. Korovko et al. / News of the Ural State Mining University 3 (2018) 54-64

Relevance of the problem. In the Urals, in connection with the solution of the problem of supplying the operating non-ferrous metallurgy enterprises with local raw materials, a number of copper-porphyry ore-bearing deposits have been involved in the industrial development in the last decade; low-sulfidation mineralization is localized mainly in dioritic intrusive massifs. The presence of large-scale mineralization of native copper in the diorites of the Vostochno-Verkhotursky massif testifies to the need for its comprehensive study and determination of ore-forming appurtenances.
Purpose of the paper is to determine the formation and age appurtenances, as well as the metallogenic specialization of the eastern part of Verkhotursko-Isetskaya zone (Middle Urals) of the Vostochno-Verkhotursky massif within which mineralization of native copper was previously identified.
Results. Petrographic, geochemical, and isotope-geochronological studies of the gabbro, diorite and granodiorite massifs were carried out (SiO2–53.97–67.32%, K2O – 1.04–2.65%) and gabbro-diorite dikes occurring among them SiO2 – 54.50-56.50%, K2O – 0.96–1.50%). The predominantly corniferous rocks of the massif belong to a single homodromous calci-alkalic normal-alkalic series of a moderately potassic type. Dyorites of dikes are comagmatic to enclosing rocks. The massif is formed in the abyssal-mesoabyssal conditions of the supra-subduction situation at the continental margin of the zone development. The U-Pb age of the investigated rocks of the massif is determined by zircon (the method of laser ablation) in 339.2 2.8 million years (Carbonic period). The formation of the massif occurred within the tectonic block with the basement of the Proterozoic age of the sialic composition. The presence of high concentrations of F in accessory apatites (up to 3.5–4.2%) at relatively low Cl (up to 0.5%) and SO3 (up to 0.4-0.9%) indicates a possible gold-rare metal specialization of formations.
Conclusion. To determine conditions for the formation of the mineralization of native copper among the supra-subduction dioritoids of the Middle Carbonic period, its age, ore-bearing belonging, and scale, it is necessary to further study both the formations of the Vostochno-Verkhotursky massif (including those that underwent secondary alterations) and other dioritoid massifs in the eastern part of the Verkhoturskaya-Isetskaya zone.

Keywords: Vostochno-Verkhotursky massif, diorites, active continental margin, Carbonic period, native copper, rare metals.

The work was carried out within the framework of the topic No 0393-2016-0020 of the state task of the Zavaritsky Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences.

REFERENCES

1. 2011, State geological map of the Russian Federation. Scale 1 : 1 000 000 (third generation). Ural series. Sheet O-41. Ekaterinburg; Saint-Petersburg, 492 p.
2. 2003, Mineraly [Minerals]: reference book. Vol. 5: Karkasnyye silikaty [Framework silicates]. Issue 1. Silikaty s razorvannymi karkasami, polevyye shpaty [Silicates with broken frames, feldspars]. Moscow, 583 p.
3. Leake B. E., Woolley A. R. et al. 1997, Nomenclature of amphiboles. The Canadian Mineralogist, vol. 35, pp. 219–246.
4. Deer W. A., Howie R. A., Zusman J. 1966, Rock-forming minerals. Vol. 3. Listovyye silikaty [Phyllosilicates]. Moscow, 318 p.
5. Fershtater G. B. 2003, Nadsubduktsionnyy intruzivnyy magmatizm Urala [Suprasubduction intrusive magmatism of the Urals]. Geologiya i geofizika [Russian Geology and Geophysics], no. 12, pp. 134–1364.
6. Fershtater G.B. 2013, Paleozoyskiy intruzivnyy magmatizm Srednego i Yuzhnogo Urala [Paleozoic intrusive magmatism of the Middle and Southern Urals]. Ekaterinburg, 368 p.
7. Fershtater G.B., Shardakova G.Yu., Borodina N.S. 1998, O stepeni okislennosti yevropiya v granitoidakh [On the degree of oxidation of europium in granitoids]. Yearbook-1997. Ekaterinburg, P. 178-180.
8. Pearce J.A., Harris N.B.W., Tindle A.G. 1984, Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, vol. 25, pp. 956–983.
9. Frolova T. I., Burikova I. А. 1997, Magmaticheskiye formatsii sovremennykh geotektonicheskikh obstanovok [Magmatic formations of modern geotectonic environments]. Moscow, 320 p.
10. Pearce J. A., Kempton P. D., Nowell G. M., Noble S. R. 1999, Hf–Nd Element and Isotope Perspective on the Nature and Provenance of Mantle and Subduction Components in Western Pacific Arc-Basin Systems. Journal of Petrology, vol. 40, no. 11, pp. 1579–1611.
11. Smirnov V. N., Ronkin Yu. L., Puchkov V. N. et al. 2016, Novyye dannyye o genezise zemnoy kory vostochnogo sektora Srednego Urala: izotopnyye Sr–Nd-ogranicheniya [New data on the genesis of the earth’s crust of the eastern sector of the Middle Urals: isotopic Sr-Nd-constraints]. Doklady RAN [Proceedings of RAS], vol. 467, no 5, pp. 566–571.
12. Smirnov V. N., Ivanov K. S., Shokalsky S. P. 2016, Novyye dannyye o vremeni sushchestvovaniya okrainno-kontinental’noy zony subduktsii na Srednem Urale [New data on the time of existence of the marginal continental subduction zone in the Middle Urals]. Doklady RAN [Proceedings of RAS], vol. 471, no. 4, pp. 455–458.
13. Zaitseva M. V., Pupyshev A. A., Shchapova Yu. V., Votyakov S. L. 2016, U–Pb datirovaniye tsirkonov s pomoshch’yu kvadrupol’nogo mass-spektrometra s induktivno-svyazannoy plazmoy NexION 300S i pristavki dlya lazernoy ablyatsii NWR 213 [U-Pb dating of zircons using a quadrupole mass spectrometer with inductively coupled plasma NexION 300S and attachments for laser ablation NWR 213]. Analitika i kontrol' [Analytics and control], vol. 20, no. 4, pp. 294–306.
14. Zaitseva M. V., Votyakov S. L. 2017, K metodike opredeleniya U–Pb-vozrasta i analiza Lu–Hf-izotopnoy sistemy tsirkona metodom LA-ISP-MS [To the procedure for determining the U-Pb-age and analyzing the Lu-Hf-isotope zircon system by the LA-ISP-MS method]. Ezhegodnik–2016: Trudy IGG UrO RAN [Yearbook-2016], issue 164, pp. 284–289.
15. Andersen T. 2008, Appendix A3: COMPBCORR – Software for common lead correction of U–Th–Pb analyses that do not report 204Pb. Mineralogical Association of Canada, vol. 40, pp. 1–18.
16. Smirnov V. N., Ivanov K. S., Larionov A. N. 2014, Vozrast i geodinamicheskiye usloviya formirovaniya granitoidov Verkhisetskogo batolita, vostochnyy sklon Srednego Urala (po rezul’tatam U–Pb SIMS-datirovaniya tsirkonov) [Age and geodynamic conditions for the formation of granitoids of the Upper Batholith, the eastern slope of the Middle Urals (based on the results of U-Pb SIMS-dating of zircons)]. Stratigrafiya. Geologicheskaya korrelyatsiya [Stratigraphy and Geological Correlation], vol. 22, no. 6, pp. 26–44.
17. Kholodnov V. V., Bushlyakov I. N. 2002, Galogeny v endogennom rudoobrazovanii [Halogen in endogenous ore formation]. Ekaterinburg, 394 p.
18. Barberi F., Ferrara G., Santacroce R. 1975, A transitional basalt-pantellerite seguence of fractional cristallisation, the Boina centre (Afar rift, Ethiopia). Journal of Petrology, no. 1, pp. 65–78.
19. Taylor S. R., McLennan S. M. 1985, The Continental Crust: Its Composition and Evolution. Oxford, 312 p.
20. Sun S.-S., McDonough W. F. 1989, Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes.
A. D. Saunders and M. J. Norry (eds.). Magmatism in the oceanic basins. Geological Society, London, Special Publications. No. 42, pp. 313–345.
21. Montero P., Bea F. et al. 2000, Single-zircon evaporation ages and Rb–Sr dating of four major Variscan batholiths of the Urals. A perspective of the timing of deformation and granite generation. Tectonophysics, no. 317, pp. 93–108.
22. Fershtater G. B. 2015, Geokhimicheskiye trendy gabbro i granitov Urala, otrazhayushchiye istoriyu geologicheskogo razvitiya podvizhnogo poyasa [Geochemical trends of the gabbro and granites of the Urals, reflecting the history of the geological development of the mobile belt]. Geokhimiya [Geochemistry International], no. 12, pp. 1094–1109.
23. Fershtater G. B. et al. 2001, Evolyutsiya sostava verkhney mantii i zemnoy kory Urala po dannym petrologicheskogo, geokhimicheskogo, izotopnogo izucheniya magmaticheskikh assotsiatsiy (ul’tramafit-mafitovyye, gabbro-granitoidnyye i granitoidnyye serii) [Evolution of the composition of the upper mantle and the Earth’s crust of the Urals according to petrological, geochemical, isotopic studies of magmatic associations (ultramafic-mafic, gabbro-granitoid and granitoid series)]. Yearbook-2000. Ekaterinburg, pp. 232–236.
24. Fershtater G. B. 1990, Empiricheskiy plagioklaz-rogovoobmankovyy barometr [Empirical plagioclase-hornblende barometer]. Geokhimiya [Geochemistry International], no. 3, pp. 328–342.
25. Schmidt M. W. 1993, Phase relations and compositions in tonalite as a function of pressure; an experimental study at 650 °C. American Journal of Science, vol. 293, pp. 1011–1060.
26. Holland T., Blundy J. 1994, Non-ideal interactions in calcic amphiboles and their bearing on amphibole-plagioclase thermometry. Contributions to Mineralogy and Petrology, vol. 116, pp. 433–447.