Early Palaeoproterozoic granulite-facies metamorphism and partial melting of eclogite-facies rocks in the Salma association, eastern Fennoscandian Shield, Russia

The Salma-type Archaean eclogites exposed along the northwestern boundary of the Belomorian Eclogite Province in the eastern Fennoscandian Shield formed as a result of the Mesoarchaean–Neoarchaean subduction and collision. The common protoliths of the Salma-type subduction-related eclogites were oceanic layered gabbro and volcanic-sedimentary assemblage. The eclogite-facies pillow lavas and associated alumina-siliceous sediments that fill interpillow space and intercalate with lava flows are the main objects of our work. The kyanite-garnet–phengite–quartz rocks formed after alumina-siliceous sediments contain fluid inclusions trapped in large relic quartz grains. The fluid inclusions yielded an isochore that corresponds to PT-conditions of a beginning of the Salma oceanic rock subduction from the seafloor level that generally confirms the sedimentary provenance of these rocks. The alumina-siliceous sediments underwent the eclogite-facies metamorphism at pressure no lower than 21 kbar and temperatures of 650–750 °C and transformed into kyanite-garnet–phengite–quartz rocks. During exhumation under granulite-facies conditions at temperatures up to 900 °C and pressure down to 9 kbar, eclogite facies metasediments underwent partial melting accompanied by disequilibrium breakdown of phengite + quartz association with formation complex polymineralic pseudomorphs consisting of feldspars, biotite, muscovite, kyanite, corundum, and dumortierite. U-Pb dating of Th-rich igneous zircon from melted metasedimentary and mafic rocks using the LA-ICP-MS and TIMS methods yielded the time of granulite facies event accompanied by partial melting processes at ~2.45 Ga. After this, zircon underwent fluid-induced alteration, causing partial dissolution followed by precipitation of new Th–poor zircon and zircon rims around ancient grains at ~1.9 Ga ago © 2021 Elsevier B.V.

Authors
Dokukina K.1 , Mints M.V. 1 , Khubanov V.B.2 , Sheshukov V.S.1 , Konilov A.N. 1, 3 , Bayanova T.B.4 , Kaulina T.V. 4 , Golunova M.A.2 , Dokukin P.A. 5 , Okina O.I.1 , Van K.V. 3 , Yudin D.S.6, 7 , Travin A.V.6, 7 , Zaitsev A.V. 1 , Kosorukov V.L.8 , Pozhilenko V.I.4 , Golovanova T.I.9
Language
English
Status
Published
Number
106260
Volume
361
Year
2021
Organizations
  • 1 Geological Institute of RAS, Moscow, Russian Federation
  • 2 Geological Institute of SB RAS, Ulan-Ude, Russian Federation
  • 3 Institute of Experimental Mineralogy, RAS, Chernogolovka, Russian Federation
  • 4 Institute of Geology of the Kola Science Centre, RAS, Apatity, Russian Federation
  • 5 Peoples’ Friendship University of Russia, Moscow, Russian Federation
  • 6 Sobolev V.S. Institute of Geology and Mineralogy SB RAS, Novosibirsk, Russian Federation
  • 7 Novosibirsk State University, Russian Federation
  • 8 Lomonosov Moscow State University, Russian Federation
  • 9 Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS, Moscow, Russian Federation
Keywords
Eclogite; Granulite; Metasedimentary rocks; Partial melting; Pillow lava; U-Pb dating
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