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.

中文翻译：

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西伯利亚地台比利亚克昌带和鄂霍次克地块交界处火山-陆源岩的古元古代（2055-2050 Ma）

首次确定代表鄂霍次克地块与西伯利亚台地交汇带的乌尔坎-比利亚克山火山-深成岩带北部碎片的比利亚克群时代（2055-2050 Ma）。该年龄是根据 Nudym 杂岩侵入的白质花岗岩的 U-Pb 年龄（2050±3.3 Ma）和 Bilyakchan 群砂岩中最年轻的碎屑锆石颗粒群的 U-Pb 年龄（2054±9 Ma）确定的）。早古元古代岩石（2110-2050 Ma）在比利亚克昌地堑物源区占主导地位。Bilyakchan 群比之前与之相关的 Ulkan 火山-深成岩复合体年龄大 300-350 Ma。Bilyakchan地堑的起源反映了早古元古代鄂霍次克地块脱离西伯利亚地台的阶段。