The Ulan-Sar’dag ultrabasite-basite massif is the part of the ophiolite complexes of the Dunzhugur island arc of the Paleo-Asian Ocean. Ophiolites have been formed at supra-subduction conditions of ensimatic island arcs. However, they have a heterogeneous composition corresponds to spreading and subduction settings and various geochronological dating’s. The new geochemical data on the metavolcanic rocks and peridotites of the Ulan-Sar’dag massif are obtained. Metavolcanics have a wide range of geochemical types from Mid-Ocean Ridge Basalts to Ocean Island Basalts. According to geochemical characteristics four groups of volcanics have been identified: (1) highly magnesian metabasalts (possibly picrites); they correspond to Island Arc Tholeiites and Enriched Mid‐Ocean Ridge Basalts, they have low (La/Yb) from 1,89 to 2,94, (Nb/Y) from 0,19 to 0,27; (2) andezi-basalt (boninite); they correspond to Calk Alkaline Basalts and Normal Mid-Ocean Ridge Basalts, it has low REE negative anomalies HFSE, low (La/Yb) = 1,41, (Nb/Y) = 0,12; (3) andesites-plagiodacites which belong to island-arc volcanics; REE, HFSE, LILE pattern correspond to continental crust, (La/Yb) vary from 5 to 13; (Nb/Y) vary from 0,49 to 0,65; (4) alkali metavolcanics; they correspond to Ocean Island Basalts, high (La/Yb) vary from 13 to 43; (Nb/Y) vary from 1,38 to 1,65. The metavolcanites lie on the trend from Normal Mid-Ocean Ridge Basalts to Ocean Island Basalts, in terms (Nb/Yb) – (Th/Yb). Metaperidotites and metavolcanics of the Ulan-Sar’dag massif, have geochemical characteristics corresponding to suprasubduction ophiolites, which does not disagree the previously obtained data on the Dunzhugur island arc. There have been several magmatic events. The geochemical features of the studied rocks reflect different stages of initiation and development of the island arc. In addition, the obtained new data on the volcanic rocks of the Ulan- Ulan-Sar’dag massif (enriched metabasalts, alkaline metavolcanic rocks) indicate spreading environments and possibly the the occurrence of local plume magmatism according to the slab-window mechanism in the subducted plate.

Kiseleva Olga Nikolaevna, Candidate of Sciences (Geology and Mineralogy), Research Scientist, V. S. Sobolev Institute of Geology and Mineralogy SB RAS, 3, Academic Koptug st., Novosibirsk, 630090, Russian Federation, tel.: (383) 373-05-26, e-mail: kiseleva_on@igm.nsc.ru 

Airiyants Evgeniya Vladimirovna, Candidate of Sciences (Geology and Mineralogy), Senior Research Scientist, V. S. Sobolev Institute of Geology and Mineralogy SB RAS, 3, Academic Koptug st., Novosibirsk, 630090, Russian Federation, tel.: (383) 373-05-26, e-mail: jenny@igm.nsc.ru 

Belyanin Dmitriy Konstantinovich, Candidate of Sciences (Geology and Mineralogy), Research Scientist, V. S. Sobolev Institute of Geology and Mineralogy SB RAS, 3, Academic Koptug st., Novosibirsk, 630090, Russian Federation; Senior Lecture, Novosibirsk State University, 2, Pirogov st., Novosibirsk, 630090, Russian Federation, tel.: (383) 373-05-26, e-mail: bel@igm.nsc.ru 

Zhmodik Sergei Mikhailovich, Doctor of Science (Geology and Mineralogy), Leading Researcher, V. S. Sobolev Institute of Geology and Mineralogy SB RAS, 3, Academic Koptug st., Novosibirsk, 630090, Russian Federation; Leading Research Scientist, Novosibirsk State University, 2, Pirogov st., Novosibirsk, 630090, Russian Federation, tel.: (383) 373-05-26, e-mail: zhmodik@igm.nsc.ru

Kiseleva О.N., Airiyants Е.V., Belyanin D.K., Zhmodik S.M. Geochemical Features of Peridotites and Volcanogenic-Sedimentary Rocks of the Ultrabasic-Basitic Massif of Ulan-Sar’dag (East Sayan, Russia). The Bulletin of Irkutsk State University. Series Earth Sciences, 2019, vol. 27, pp. 46-61. https://doi.org/10.26516/2073-3402.2019.27.46 (in Russian)

Sklyarov E.V. [et al.] Boninity i ofiolity: problemy ih sootnoshenija i petrogenezisa boninitov [Boninites and ophiolites: problevs of their relations and petrogenesis of boninites]. Geologija i geofizika [Geology and Geophysics], 2016, vol. 57, no. 1, pp. 127-140. (in Russian)

Kuz'michev A.B. Tektonicheskaja istorija Tuvino-Mongol'skogo massiva: rannebajkal'skij, pozdnebajkal'skij i rannekaleodonskij jetapy [The tectonic history of the Tuva – MongolianMassif: Early Baikalian, late Baikalian, and early Caledonian stages]. Moscow, Probel Publishing House, 2004, 192 p. (in Russian).

Kuz'michev A.B., Larionov A.N. Neoproterozojskie ostrovnye dugi Vostochnogo Sajana: dlitel'nost' magmaticheskoj aktivnosti po rezul'tatam datirovanija vulkanoplatiki po cirkonam [Neoproterozoic island arcs of East Sayan: duration of magmatism (from U-Pb zircon dating of volcanic clastics)]. Geologija i geofizika [Geology and Geophysics], 2013, vol. 54, no. 1, pp. 45-57. (in Russian)

Skopintsev V.G. Geologicheskoe stroenie i poleznye iskopaemye verhov'ev rek Gargan, Urik, Kitoj, Onot; rezul'taty poiskovyh rabot na uchastke Kitojskom (Vostochnyj Sajan). [Geological structure and mineral resources of the upper rivers Gargan, Urik, Kitoy, Onot; results of prospecting works on the site of Kitoy (East Sayan)]. Report of the Samartin and Kitoy parties. Book 1, 1995, 319 p. (in Russian)

Kiseleva O.N., Zhmodik S.M., Damdinov B.B., Agafonov L.V., Belyanin D.K. Sostav i jevoljucija platinometal'noj mineralizacii v hromitovyh rudah Il'chirskogo ofiolitovogo kompleksa (Ospino-Kitojskij i Haranurskij massivy, Vostochnyj Sajan) [Composition and evolution of PGE mineralization in chromite ores from the Il’chir ophiolite complex (Ospa-Kitoi and Khara-Nur areas, East Sayan)]. Geologija i geofizika [Geology and Geophysics], 2014, vol. 55, pp. 259-272. (in Russian)

Khanchuk A.I., Vysotskiy S.V. Raznoglubinnye gabbro-giperbazitovye associacii v ofiolitah Sihotje-Alinja (Dal'nij Vostok Rossii) [Different-depth gabbro–ultrabasite associations in the Sikhote-Alinophiolites (Russian Far East)] Geologija i geofizika [Geology and Geophysics], 2016, vol. 57, no. 1, pp. 181-198. (in Russian)

Shchipansky A.A. Subdukcionnye i mantijno-pljumovye processy v geodinamike formirovanija arhejskih zelenokamennyh pojasov. [Subduction and mantle-plume processes in geodynamics of formation of Archaean greenstone belts]. Moscow, LCI Publ., 2008, 560 p. (in Russian)

Nikolaeva I.V., Palesskii S.V., Koz’menko O.A., Anoshin G.N. Analysis of geologic reference materials for REE andHFSE by inductively coupledplasma mass spectrometry (ICP-MS). Geochemistry International, 2008, vol. 46, no. 10, pp. 1016-1022. https://doi.org/10.1134/S0016702908100066

Anders E., Grevesse N. Abundances of the elements: meteoritic and solar. Geochim. Cosmochim. Acta, 1989, vol. 53, pp. 197-214.

Crawford A.J., Fallon T.J., Green D.H. Classification, petrogenesis and tectonic setting of boninites. Boninites, A.J. Crawford (ed.). London, Unwin Hyman, 1989, pp. 2-44. 

Dasgupta R., Hirschmann M.M., Smith N.D. Water follows carbon: CO2 incites deep silicate melting and dehydration beneath mid-ocean ridges. Geology, 2007, vol. 35, pp. 135-138. https://doi.org/10.1130/G22856A.1.

Eyuboglu Y., Santosh M., Keewook Y., Bektaş O., Kwon S. Discovery of Miocene adakitic dacite from the Eastern Pontides Belt (NE Turkey) and a revised geodynamic model for the late Cenozoic evolution of the Eastern Mediterranean region. Lithos, 2012, vol. 146-147, pp. 218-232. https://doi.org/10.1016/j.lithos.2012.04.034

Dobretsov N.L., Konnikov E.G., Dobretsov N.N. Precambrian ophiolitic belts of Southern Siberia, Russia, and their metallogeny. Precambrian Research, 1992, vol. 58, no. 1-4, pp. 427-446. 

Duncan R.A., Green D.H. Role of multistage melting in the formation of oceanic crust. Geology, 1980, vol. 8, no. 1, pp. 22-26. https://doi.org/10.1130/0091-7613(1980)8<22:ROMMIT>2.0.CO;2

Duncan R.A., Green D.H. The genesis of refractory melts in the formation of oceanic crust . Contrib. Mineral. Petrol., 1987, vol. 96 (3), pp. 326-342. https://doi.org/10.1007/BF00371252.

Pearce, J.A., Thirlwall, M.F., Ingram, G., Murton, B.J., Arculus, R.J. and Van der Laan, S.R., 1992. Isotopic Evidence for the Origin and Evolution of the Izu-Ogasawara Forearc at Sites 782 and 786 (ODP Leg 125). Proc. ODP Scientific Results, 1992, vol. 125, pp. 237-261.

Kamber B.S., Collerson K.D. Zr/Nb systematics of ocean island basaltsreassessed – the case for binary mixing. Journal of Petrology, 2000, vol. 41, pp. 1007-1021. https://doi.org/org/10.1093/petrology/41.7.1007

Kiseleva O.N., Zhmodik S.M. PGE mineralization and melt composition of chromitites in Proterozoic ophiolite complexes of Eastern Sayan, Southern Siberia. Geoscience Frontiers, 2017, vol. 8, no. 4, pp. 721-731. https://doi.org/10.1016/j.gsf.2016.04.003.

Le Bas M.J. IUGS reclassification of the high-Mg and picritic volcanic rocks. Journal of Petrology, 2000, vol. 41, pp. 1467-1470. https://doi.org/10.1093/petrology/41.10.1467.

Haeussler P.J., Bradley D., Goldfarb R., Snee L., Taylor C. Link between ridge subduction and gold mineralizationin southern Alaska. Geology, 1995, vol. 23, pp. 995-998. https://doi.org/10.1130/0091-7613(1995)023<0995:LBRSAG>2.3.CO;2

Ludden J., Gelienas L., Trudel P. Archean metavolcanics from the Rouyn-Noranda distinct, Abitibi greenstone belt, Quebec: 2. Mobility of trace elements and petrogenetic constraints. Can. J. Earth. Sci., 1982, vol. 19, pp. 2276-2287. https://doi.org/10.1139/e82-200

Hart S.R., Hauri E.N., Oschmann L.A., Whitehead J.A. Mantle plumes and entrainment: isotopic evidence. Science, 1992, vol. 256, pp. 517-520.

Miao Y., Yu L., Blunsom Ph. Neural variational inference for text processing. Proceedings of ICML, 2016, pp. 1727-1736.

Mullen E.D. MnO/TiO₂/P₂O₅: a minor element discriminant for basaltic rocks of oceanic environments and its implications for petrogenesis. Earth Planet. Sci. Lett., 1983, vol. 62, pp. 53-62.

Zhmodik S., Kiseleva O., Belyanin D., Damdinov B., Airiyants E., Zhmodik A. PGE mineralization in ophiolites of the southeast part of the Eastern Sayan (Russia), 12th International Platinum Symposium. Abstracts, Anikina E.V. et al. (eds). Yekaterinburg: Institute of Geology and Geochemistry UB RAS, 2014. pp. 221-225.

Pearce J.A. Trace elements characteristics of lavas from destructive plate boundaries: andesites, orogenic andesites and related rocks. Thorpe R.S. (Eds). Wiley, Chichester, 1982, pp. 525-548.

Gazel E., Hoernle K., Carr M.J., Herzberg C., Saginor I., Van den Bogaard P., Hauff F., Feigenson M., Swisher III C. Plume–subduction interaction in southern Central America: Mantle upwelling and slab melting. Lithos, 2011, vol. 121 (1-4), pp. 117-134. https://doi.org/10.1016/j.lithos.2010.10.008.

Saccani E., Principi G. Petrological and tectono-magmatic significance of ophiolitic basalts from the Elba Island within the Alpine Corsica-Northern Apennine system. Mineralogy and Petrology, 2016, vol. 110 (6), pp. 713-730. https://doi.org/10.1007/s00710-016-0445-3

Safonova I., Santosh M. Accretionary complexes in the Asia-Pacific region: tracing archives of ocean platestratigraphy and tracking mantle plumes. Gondwana Research, 2014, vol. 25 (1), pp. 126-158. https://doi.org/10.1016/j.gr.2012.10.008

Santosh M., Kusky T. Origin of paired high pressure-ultrahigh-temperature orogens: a ridge subduction and slab window model. Terra Nova, 2010, vol. 22 (1), pp. 35-42.

Sun S.S., Nesbitt R.W. Geochemical regularities and genetic significance of ophiolitic basalts. Geology, 1978, vol. 6, no. 11, pp. 689-693. https://doi.org/10.1130/0091-7613(1978)6<689:GRAGSO>2.0.CO;2

Sun S.S., McDonough W.F. Chemical and isotopic systematics of oceanic basalts; implications for mantle composition and processes. Magmatism in the ocean basins. Saunders A. D., Norry M. J. (eds). Geological Society of London, London, 1989, vol. 42, pp. 313-345.

Kay S.M., Ardolino A.A., Gorring M., Ramos V. The Somuncura Large igneous province in Patagônia: interaction of a transient mantle thermal anomaly with a subducting slab. Journal of Petrology, 2007, vol. 48, no. 1, pp. 43-77. https://doi.org/10.1093/petrology/egl053.

Thorkelson D.J. Subduction of diverging plates and the principles of slab window formation. Tectonophysics, 1996, vol. 255, pp. 47-63.

Weaver B.L. The origin of ocean island basalt and member compositions: trace element and isotope constrain. Earth Planet. Sci. Lett., 1991, vol. 104, pp. 381-397. https://doi.org/10.1016/0012-821X(91)90217-6

Wilson M. Geochemical signatures of oceanic and continental basalts: a key to mantle dynamics? Journal of the Geological Society, 1993, vol. 150, pp. 977-990. 

Wood D.A. The application of a Th-Hf-Ta diagram to problems of tectonomagmatic classification and to establishing the nature of crustal contamination of basaltic lavas on the British Tertiary Volcanic Province. Earth Planet. Sci. Lett., 1980, vol. 50, pp. 11-30. https://doi.org/10.1016/0012-821X(80)90116-8.