• Late Devonian and Triassic basalts from the southern continental margin of the East European Platform, tracers of a single heterogeneous lithospheric mantle source

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      https://www.ias.ac.in/article/fulltext/jess/116/06/0469-0495

    • Keywords

       

      Basalts; East European Platform; Late Devonian; Triassic; Donbas; Fore-Caucasus; geochemistry; geodynamics; geology.

    • Abstract

       

      In Late Devonian and Early-to-Late Triassic times, the southern continental margin of the Eastern European Platform was the site of a basaltic volcanism in the Donbas and Fore-Caucasus areas respectively. Both volcanic piles rest unconformably upon Paleoproterozoic and Late Paleozoic units respectively, and emplaced during continental rifting periods some 600 km away from expected locations of active oceanic subduction zones.

      This paper reports a comparative geochemical study of the basaltic rocks, and views them as the best tracers of the involved mantle below the Eastern European Platform. The Late Devonian alkaline basic rocks differ from the calc-alkaline Triassic basic rocks by their higher alkali-silica ratio, their higher TiO2, K2O, P2O5 and FeO contents, their higher trace element contents, a higher degree of fractionation between the most and the least incompatible elements and the absence of Ta-Nb negative anomalies. These general features, clearly distinct from those of partial melting and fractional crystallization, are due to mantle source effects. With similar Nd and Sr isotopic signatures indicating mantle-crust mixing, both suites would originate from the melting of a same but heterogeneous continental mantle lithosphere (refertilized depleted mantle). Accordingly the Nd model ages, the youngest major event associated with mantle metasomatism occurred during Early Neoproterozoic times (∼650Ma).

    • Author Affiliations

       

      Françoise Chalot-Prat1 Petr Tikhomirov2 Aline Saintot3 4

      1. Centre de Recherches Petrographiques et Geochimiques – Nancy University, BP20, 15 rue Notre Dame des Pauvres, F-54501 Vandoeuvre-les-Nancy Cedex, France.
      2. Geological Faculty of Moscow State University; Vorobiovy Gory, 117311 Moscow, Russia.
      3. Vrije Universiteit, Instituut voor Aardwetenschappen, Tektoniek afdeling, De Boelelaan 1085, 1081 HV Amsterdam, Netherlands.
      4. Geological Survey of Norway, N-7491 Trondheim, Norway.
    • Dates

       
  • Journal of Earth System Science | News

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