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The Early Baikalian crystalline complex in the basement of the Dzabkhan microcontinent of the Early Caledonian orogenic area, Central Asia |
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| Authors: | I K Kozakov V V Yarmolyuk V P Kovach E V Bibikova T I Kirnozova A M Kozlovskii Yu V Plotkina M M Fugzan V I Lebedev Ch Erdenezhargal |
| Institution: | 1. Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St.-Petersburg, Russia 2. Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of Sciences (IGEM RAS), Moscow, Russia 3. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow, Russia 4. Tuva Institute of Complex Exploration of Natural Resources, Siberian Branch of the Russian Academy of Sciences, Kyzyl, Russia 5. Institute of Geology and Mineral Resources, Mongolian Academy of Sciences, Ulan Bator, Mongolia |
| Abstract: | Fragments of continental blocks or microcontinents are represented in the Early Caledonian orogenic area of Central Asia (or Early Caledonian superterrane); the largest of these are the Dzabkhan and Tuva-Mongolian microcontinents, with Early and Late Precambrian crystalline basements, respectively. In the linkage zone of these microcontinents, crystalline rocks of the Tarbagatai and Songino blocks that are considered as units of the Early Precambrian ensialic basement of the superterrane are also known. They are composed of strongly metamorphosed rocks formed during the Early Baikalian orogeny about 790 to 820 Ma. U-Pb zircon dating and Nd isotope studies revealed, within the northwestern Dzabkhan microcontinent, the Dzabkhan-Mandal zone of crystalline rocks associated with the Riphean crust-forming process. The age of the gneiss substrate of this zone is estimated as 1.3 to 0.86 Ga. An early episode of metamorphism is dated at about 856 ± 2 Ma. The data available so far indicate a heterogeneous structure of the Dzabkhan microcontinent basement represented by Early Precambrian and Early and Late Baikalian crystalline formations. |
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