Age of carbonate rocks of the agaringol formation (Northern Mongolia): possibilities of Pb-Pb dating

Abstract

The article discusses in detail the possibility of using the Pb-Pb method to date Neoproterzoic carbonates. The Pb-Pb method has been used to date the limestone of the Agarin-gol Formation. The U-Pb system was studied in carbonate samples which conformed to the geochemical criteria of retention (Mg/Ca, Mn/Sr, Fe/Sr and 87Sr/86Sr) and have undergone a step-dissolution procedure. In 206Pb/204Pb—207Pb/204Pb coordinates, the age of the Agarin-gol limestone is to 621±93 Ma, MSWD=1.3. This age is consistent with the Ediacaran age established on the basis of the Sr isotope chemostratigraphy (87Sr/86Sr = 0.70740–0.70748). New data allows for the specification of the sedimentation age of carbonate sediments, which is Vendian-Cambrian stage of the Tuva-Mongolian Massif. Refs 35. Figs 7. Tables 2.