Russian Journal of Earth Sciences Russian Journal of Earth Sciences Russian Journal of Earth Sciences 1681-1208 47111 ОРИГИНАЛЬНЫЕ СТАТЬИ ORIGINAL ARTICLES ОРИГИНАЛЬНЫЕ СТАТЬИ Low mantle plume component in 370 Ma old Kola ultrabasic-alkaline-carbonatite complexes: Evidences from rare gas isotopes and related trace elements Low mantle plume component in 370 Ma old Kola ultrabasic-alkaline-carbonatite complexes: Evidences from rare gas isotopes and related trace elements Tolstikhin I N Tolstikhin I N Kamensky I L Kamensky I L Nivin V A Nivin V A Vetrin V R Vetrin V R Balaganskaya E G Balaganskaya E G Ikorsky S V Ikorsky S V Gannibal M A Gannibal M A Kirnarsky Yu M Kirnarsky Yu M Marty B Marty B Weiss D Weiss D Verhulst A Verhulst A Demaiffe D Demaiffe D Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru v ru v ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Geological Institute, Kola Scientific Centre, Russian Academy of Sciences, Apatity, Russia ru Centre National de la Recherche Scientifique Centre de Recherches Petrographiques et Geochimiques C.R.P.G. Vandoeuvre-Nancy Cedex, France ru Centre National de la Recherche Scientifique Centre de Recherches Petrographiques et Geochimiques C.R.P.G. Vandoeuvre-Nancy Cedex, France ru Petrologie et Geodynamique Chimique Department des Sciences de la Terre et de l'Environnement Faculte des Sciences Universite Libre de Bruxelles, Bruxelles, Belgique ru Petrologie et Geodynamique Chimique Department des Sciences de la Terre et de l'Environnement Faculte des Sciences Universite Libre de Bruxelles, Bruxelles, Belgique ru Petrologie et Geodynamique Chimique Department des Sciences de la Terre et de l'Environnement Faculte des Sciences Universite Libre de Bruxelles, Bruxelles, Belgique ru Petrologie et Geodynamique Chimique Department des Sciences de la Terre et de l'Environnement Faculte des Sciences Universite Libre de Bruxelles, Bruxelles, Belgique ru Petrologie et Geodynamique Chimique Department des Sciences de la Terre et de l'Environnement Faculte des Sciences Universite Libre de Bruxelles, Bruxelles, Belgique ru Petrologie et Geodynamique Chimique Department des Sciences de la Terre et de l'Environnement Faculte des Sciences Universite Libre de Bruxelles, Bruxelles, Belgique ru 1 2 179 222 11 11 2021 https://rjes.ru/en/nauka/article/47111/view

During Devonian pulse of alkaline magmatism 370 Ma ago 18 ultrabasic-alkaline-carbonatite complexes were formed on the Kola Peninsula. Rare gas isotope abundances were studied in ~300 samples from 8 complexes and also from Devonian dikes. A comparison of expected from in-situ closed-system production calc and measured meas abundances has shown that 4He meas 4Hecalc whereas in some rocks and minerals 3Hemeas exceeded 3Hecalc up to 1,000 times indicating occurrence of a mantle fluid in a majority of samples. Gas extraction liberated fluid-related helium with as low 4He/3He ratios as 3 x 104. These values show a contribution of 3He-rich plume-like component. A reason for highly variable 4He/3He ratios is not well understood yet. Isotope composition of Ne supports the occurrence of plume component: 20Ne/22Ne ratio varies from 10.4 to 12.0 and 20Ne/22Ne versus 21Ne/22Ne correlation is quite similar to that observed for Loihi hot spot, Hawaii. A comparison of these data with rare gas systematic in the mantle enable us to suggest a contribution of material from the less degassed deep mantle reservoir, source of primordial rare gases, to Devonian ultrabasic-alkaline and carbonatite rocks on the Kola Peninsula.

During Devonian pulse of alkaline magmatism 370 Ma ago 18 ultrabasic-alkaline-carbonatite complexes were formed on the Kola Peninsula. Rare gas isotope abundances were studied in ~300 samples from 8 complexes and also from Devonian dikes. A comparison of expected from in-situ closed-system production calc and measured meas abundances has shown that 4He meas 4Hecalc whereas in some rocks and minerals 3Hemeas exceeded 3Hecalc up to 1,000 times indicating occurrence of a mantle fluid in a majority of samples. Gas extraction liberated fluid-related helium with as low 4He/3He ratios as 3 x 104. These values show a contribution of 3He-rich plume-like component. A reason for highly variable 4He/3He ratios is not well understood yet. Isotope composition of Ne supports the occurrence of plume component: 20Ne/22Ne ratio varies from 10.4 to 12.0 and 20Ne/22Ne versus 21Ne/22Ne correlation is quite similar to that observed for Loihi hot spot, Hawaii. A comparison of these data with rare gas systematic in the mantle enable us to suggest a contribution of material from the less degassed deep mantle reservoir, source of primordial rare gases, to Devonian ultrabasic-alkaline and carbonatite rocks on the Kola Peninsula.

 mantle plume rare gas isotopes trace elements. mantle plume rare gas isotopes trace elements.

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