Vendian stage in formation of the Early Caledonian superterrane in Central Asia

• Published in: Stratigraphy and geological correlation Vol. 16; no. 4; pp. 360 - 382
• Main Authors: Kozakov, I. K., Sal’nikova, E. B., Kovach, V. P., Yarmolyuk, V. V., Anisimova, I. V., Kozlovskii, A. M., Plotkina, Yu. V., Myskova, T. A., Fedoseenko, A. M., Yakovleva, S. Z., Sugorakova, A. M.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.08.2008; Springer Nature B.V
• Subjects: Archaeology; Earth and Environmental Science; Earth Sciences; Evolution; Geochemistry; Geophysics/Geodesy; Historical Geology; Metamorphic rocks; Plate tectonics; Sedimentology; Stratigraphy; Structural Geology; geochronology; zircon; Baidarik block; Caledonides; Dzabkhan microcontinent; metamorphism; Central Asia foldbelt; tectonics; Nd systematics; Vendian
• ISSN: 0869-5938; 1555-6263
• DOI: 10.1134/S0869593808040023

Granitoids and metamorphic rocks of the Baidarik basement block of the Dzabkhan microcontinent are studied in terms of geology, geochronology (U-Pb dating of zircon microfractions and individual grains) and Nd isotopic-geochemical systematics. As is established, the formation history of metamorphic belt (disthene-sillimanite facies) in junction zone of the Baidarik block and Bayankhongor zone of the Late Riphean (∼665 Ma) ophiolite association characterizes development of the Vendian (∼560–570 Ma) active continental margin. The high-P metamorphic rocks of that time span evidence formation of structures with the Earth’s crust of considerable thickness. In Central Asia, events of the Vendian low-gradient metamorphism are established also in the Tuva-Mongolian massif, Kan block of the East Sayan Mountains, and South Chuya inlier of the Caledonides in the Altai Mountains. Based on these data, it is possible to distinguish the Late Baikalian stage in development of the Early Caledonian superterrane of Central Asia, which antedated the subsequent evolution of this structure during the Late Cambrian-Ordovician. The high-gradient metamorphism that affected most intensively the southeastern part of the Baidarik block can be correlated with the Early Paleozoic (525–540 Ma) evolution of active continental margin and associated development of the Vendian oceanic basins and island arcs of the Ozernaya zone.