Abstract: The age of the Bilyakchan Group, representing the northern fragment of the Ulkan–Bilyakchan volcano-plutonic belt of the Okhotsk Massif and Siberian platform junction zone is established for the first time (2055–2050 Ma). This age is determined in accordance with the U–Pb age of intruded leucogranites of the Nudym complex (2050 ± 3.3 Ma) and the U–Pb age of the youngest population of detrital zircon grains from sandstone of the Bilyakchan Group (2054 ± 9 Ma). Early Paleoproterozoic rocks (2110–2050 Ma) dominated in the provenance area of the Bilyakchan graben. The Bilyakchan Group turned out to be 300–350 Ma older than the Ulkan volcano-plutonic complex to which it was correlated earlier. The origination of the Bilyakchan graben reflects the stage of detachment of the Okhotsk Massif from the Siberian platform in the Early Paleoproterozoic.