Early Neoproterozoic (ca. 850 Ma) Bimodal Volcanic Series in the Talas Range of the North Tianshan: Indications of the Earliest Stages of the Continental Breakup of Rodinia

The Early Neoproterozoic (851 ± 4 Ma) age of the bimodal basalt-rhyolite volcanic series, exposed on the southern slope of the Talas Alatau Range of northwest Kyrgyzstan, was established by U–Th–Pb (SHRIMP) zircon dating. High concentrations of titanium, iron, and phosphorus in basalts, as well as the distribution of trace elements, similar to those in the OIB, indicate intraplate tectonic settings of volcanism. Revealed magmatic episode corresponds to the earliest stages of continental break-up of Rodinia. New age suggests that rifting in the marginal parts of Rodinia in the northwest Tianshan likely started 10–20 Ma earlier than in the internal areas of the supercontinent.