Publication Details

Kozakov, I., Sal'nikova, E., Nutman, A. Phillip., Kovach, V., Kotov, A., Podkovyrov, V. & Plotkina, Y. (2005). Metasedimentary complexes of the Tuva-Mongolian Massif: age, provenances and tectonic position. Stratigraphy and Geological Correlation, 13 (1), 3-25.


A complex problem of dating supracrustal rocks is unavoidable by analysis of tectonic position of polymetamorphic amphibolite and granulite complexes. Geochronological dates are necessary to constrain ages of source rocks and accumulation periods of clastic sediments, while isotopic-geochemical parameters open a possibility to estimate model ages of the crust in provenances. Using the ion microprobe SHRIMPTM (Hiroshima, Japan), clastic zircons from metasediments of the Erzin and Moren complexes of the Tuva-Mongolian massif in accretionary collage of Central Asia are dated and the Nd model age of respective rocks are estimated. The U-Th-Pb isotopic data suggest that clastic zircons from supracrustal complexes of the Tuva-Mongolian massif were derived from the Late Riphean rocks 0.70 to 0.90 Ga old. The upper age limit is determined by synmetamorphic granitoid intrusions 536 ± 6 Ma old, and stratigraphic range of the complexes presumably corresponds to the terminal Upper Riphean-Vendian. The Early Riphean (1.4-1.5 Ga) and pre-Riphean (1.9 and 2.56 Ga) dates that are established in particular cases characterize most likely the ages of rock complexes in provenances of classic sediments. To the first approximation, the accumulation period of protoliths for gneiss-migmatitic complexes of the Tuva-Mongolian massif is correlative with the incipient breakup of Rodinia (∼730 Ma ago) and opening of Vendian oceans. Accumulation of respective sediments in settings of a passive continental margin was connected with erosion of volcano-plutonic rock associations formed before the Rodinia breakup and at the commencement of this event. It is possible to assume that margins of Rodinia experienced rifting with breakout of their fragments 1.0-0.73 Ga ago, whereas formation of volcanic arcs and islands was in progress within the ocean surrounding that supercontinent. In the terminal Late Riphean and Vendian, rocks originated at that time and products of their destruction formed the basement beneath terrigenous and carbonate sediments of microcontinents, the Tuva-Mongolian massif included. Copyright © 2005 by MAIK "Nauka/Interperiodica" (Russia).