Инд. авторы:	Turkina O.M., Urmantseva L.N., Berezhnaya N.G., Presnyakov S.L.
Заглавие:	Paleoproterozoic age of the protoliths of metaterrigenous rocks in the east of the Irkut Granulite-Gneiss block (Sharyzhalgai salient, Siberian Craton)
Библ. ссылка:	Turkina O.M., Urmantseva L.N., Berezhnaya N.G., Presnyakov S.L. Paleoproterozoic age of the protoliths of metaterrigenous rocks in the east of the Irkut Granulite-Gneiss block (Sharyzhalgai salient, Siberian Craton) // Stratigraphy and Geological Correlation. - 2010. - Vol.18. - Iss. 1. - P.16-30. - ISSN 0869-5938.
Внешние системы:	DOI: 10.1134/S0869593810010028; SCOPUS: 2-s2.0-77649204322;
Реферат:	eng: The Early Precambrian granulite-gneiss complex of the Irkut Block (Sharyzhalgai salient of the Siberian Craton basement) with the protoliths represented by a wide range of magmatic and sedimentary rocks, has a long-term history including several magmatic and metamorphic stages. To estimate the age of sedimentation and metamorphism of the terrigenous deposits, the composition of the garnet-biotite, hyper-sthene-biotite, and cordierite-bearing gneisses has been studied; their isotopic Sm-Nd values have been revealed; and the U-Pb zircon dating has been performed using the SHRIMP II ion microprobe. The protoliths of the terrigenous sediments metamorphosed under conditions of the granulite facies correspond to a rock series from siltstones and graywackes to pelites. The Nd model ages of paragneisses range from 2.4 to 3.1 Ga. Zircons of the cordierite-bearing and hypersthene-biotite gneisses show the presence of cores and rims. The clastic, smoothed, and irregular shape of the cores indicates their detrital character and relicts of oscillatory zoning suggest the magmatic origin of zircon. The rim's metamorphic genesis is indicated by the lack of zoning and by the lower Th/U ratio compared to that of the cores. The age of the detrital cores (≥2.7, ~2.3, and 1.95-2.0 Ga) and metamorphic rims (1.85-1.86 Ga) defines the time of sedimentation at 1.85-1.95 Ga ago. Potential sources for the Archean detrital zircons were metamagmatic rocks of the granulite-gneiss complexes in the southwestern margin of the Siberian Craton. The age of the dominant detrital cores at 1.95-2.0 Ga ago, together with the minimal TNd(DM) values, indicates the contribution of the juvenile Paleoproterozoic crust to the formation of sediments. The juvenile Paleoproterozoic crust was likely represented by magmatic complexes similar to the volcanic and granitoid associations of the Aldan shield, which were formed 1.99-2.0 Ga ago and showthe model age of 2.0-2.4 Ga. The isotopic Sm-Nd data show that the Late Paleoproterozoic metasedimentary rocks occur not only in the Sharyzhalgai salient but in the Aldan and Anabar shields of the Siberian Craton as well. © Pleiades Publishing, Ltd., 2010.
Ключевые слова:	Sakha; Russian Federation; Anabar Shield; Aldan Shield; uranium-lead dating; terrigenous deposit; siltstone; protolith; Proterozoic; Precambrian; metasedimentary rock; Siberian Platform; ion microprobe; graywacke; granulite facies; detrital deposit; U-Pb age; Sharyzhalgai salient; Paleoproterozoic metamorphism; Metaterrigenous rocks; Granulite-gneiss complex; Detrital zircon; metamorphism;
Издано:	2010
Физ. характеристика:	с.16-30