The Age and Sources of Protoliths of Metasedimentary Rocks in the Eastern Tukuringra Terrane of the Mongol–Okhotsk Fold Belt: Results of U–Th–Pb, Lu–Hf, and Sm–Nd Isotope Studies.

This article presents U–Th–Pb and Lu–Hf detrital zircon isotope data, as well as whole-rock Sm–Nd isotope data on metasedimentary rocks from the eastern part of the Tukuringra Terrane. Our analyses show that the zircons in metasedimentary rocks are mostly early Mesozoic. The Early Mesozoic, Early Paleozoic and Neoproterozoic zircons are predominant and Early Precambrian zircons are almost absent in these rocks. The age of the youngest zircon population places a lower age limit of sedimentation at 204 Ma for the Tungala Formation (Upper Triassic, Rhaetian), at 181 Ma for the Dugda Formation (Lower Jurassic, Toarcian), and at 189 Ma for the Tangomen Formation (Lower Jurassic, Pliensbachian). Practically all Mesozoic, Paleozoic, and Neoproterozoic zircons are characterized by Neo- and Mesoproterozoic Hf-model ages (t_Hf(DM)) = 1.41–0.46 Ga, t_Hf(C) = 1.55–0.49) and Mesoproterozoic Nd-model ages (t_Nd(DM) = 1.25–1.10 Ga, t_Nd(C) = 1.31–1.14). These results indicate that the sedimentary rocks were mainly sourced from the Amur continental superterrane, but not from the southern framing of the North Asian Craton. [ABSTRACT FROM AUTHOR]