Provenance sources of Upper Proterozoic and Lower Paleozoic clastic deposits of the Lesser Khingan terrane, Central Asian fold belt: U–Pb (LA–ICP–MS) geochronological results

Resumo

The ages of detrital zircons from sandstones and silty sandstones from conditionally Upper Proterozoic–Cambrian rocks have been obtained for the first time. These deposits are united in the Khingan Group and are one of the most ancient formations in the Lesser Khingan terrane in the eastern part of the Central Asian fold belt. These data along with relationships with granitoids imply that the ages of the Muranda and underlying Igincha Formations range within the Tonian–Ediacaran time span, while the age of the Kimkan unit is Late Cambrian–Early Ordovician. Given that the Muranda and Igincha Formations, on the one hand, and the Kimkan unit, on the other hand, are substantially different in age and structurally separated by granitoids intruded at the Ediacaran–Cambrian boundary, we should accept that they cannot be regarded as a single sedimentary sequence.