Инд. авторы:	Ovchinnikova G.V., Kuznetsov A.B., Vasil'eva I.M., Gorokhov I.M., Letnikova E.F., Gorokhovskii B.M.
Заглавие:	U-Pb age and Sr isotope signature of cap limestones from the Neoproterozoic Tsagaan Oloom Formation, Dzabkhan River Basin, Western Mongolia
Библ. ссылка:	Ovchinnikova G.V., Kuznetsov A.B., Vasil'eva I.M., Gorokhov I.M., Letnikova E.F., Gorokhovskii B.M. U-Pb age and Sr isotope signature of cap limestones from the Neoproterozoic Tsagaan Oloom Formation, Dzabkhan River Basin, Western Mongolia // Stratigraphy and Geological Correlation. - 2012. - Vol.20. - Iss. 6. - P.516-527. - ISSN 0869-5938.
Внешние системы:	DOI: 10.1134/S0869593812060056; SCOPUS: 2-s2.0-84873319478;
Реферат:	eng: The U-Pb and Pb-Pb methods were used for determining age of cap limestones from the Neoproterozoic Tsagaan Oloom Formation corresponding to the lower part of the sedimentary cover in the Dzabkahn microcontinent of Central Asia. The weighted average age value appeared to be equal to 632 ± 14 Ma (MSWD = 0. 11, probability 0. 74). This value allows the following assumptions: (1) the lower boundary of the Tsagaan Oloom Formation corresponds to the beginning of the Ediacaran; (2) Dzabkhan tillites are correlative with glacial sediments of the Marinoan Epoch. The low 238U/204Pb and 232Th/238U ratios observed in initial Pb sources of limestones from the Tsagaan Oloom Formation indicate that the Dzabkhan paleobasin received at its early development stages a bulk of material from eroded upper Riphean juvenile rocks. The 87Sr/86Sr ratio in fractions of Tsagaan Oloom limestones enriched with primary carbonate material and satisfying geochemical criteria of Rb-Sr systems retentivity (Mn/Sr < 0. 20 and Fe/Sr < 1) varies from 0. 70676 to 0. 70691 and reflects this ratio in the World Ocean approximately 630 Ma ago. © 2012 Pleiades Publishing, Ltd.
Ключевые слова:	Mongolia; Dzavhan; uranium-lead dating; tillite; strontium isotope; Proterozoic; limestone; lead-lead dating; geochronology; age determination; U-Pb and Pb-Pb ages of carbonate rocks; Tsagaan Oloom Formation; tillites; Neoproterozoic; Dzabkhan microcontinent; 87Sr/86Sr value in the ocean;
Издано:	2012
Физ. характеристика:	с.516-527