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Mesoarchean mafic dykes of the Belomorian eclogite province (Gridino Village Area,Russia) |
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| Authors: | K A Dokukina T V Kaulina A N Konilov L M Natapov E A Belousova K V Van S G Simakin E N Lepekhina |
| Institution: | 1. Geological Institute, Russian Academy of Sciences, Moscow, Russia 2. Moscow State University, Moscow, Russia 3. Institute of Geology, Kola Science Center, Russian Academy of Sciences, Apatity, Murmansk oblast, Russia 4. Institute of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka, Russia 5. ARC National Key Center, Macquarie University, Sydney, Australia 6. Yaroslavl Branch, Institute of Physics and Technology, Russian Academy of Sciences, Yaroslavl, Russia 7. Karpinskii Russian Geological Research Institute, Russian Academy of Sciences, St. Petersburg, Russia |
| Abstract: | Archean processes of eclogitization in the Gridino metamorphic association (the Belomorian eclogite province) developed in mafic dykes, boudins, and acidic rocks of the Archean continental crusts. To determine the U-Pb age of the intrusion of the latest dykes, the geochronological samples were taken from the dyke of ferriferious metagabbro that cross-cuts the dyke of eclogitzed and granulitized olivine gabbronorite. The igneous zircons were dated by the SHRIMP II technique. The zircons showed a concordia age of 2846 ± 7 Ma, which is considered as the time of intrusion of a mafic melt. The younger low-thorium zircon rims of 2.78–2.81 Ga age around the igneous cores are typical formations that appeared under metamorphic conditions in equilibrium with a migmatite melt, and may characterize the time of formation of the granite leucosome under metamorphism, probably of eclogite facies. |
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