Age and Composition of the Middle–Upper Jurassic Sediments in the Central Zone of the Polousnyi Terrane (Northern Yakutia)

Abstract

New data on the composition and structure of the Jurassic section in the Central zone of the Polousnyi Terrane are presented. The arkosic composition of sandstones and the predominance of granites in the sediment provenance was established by petrographic data. Both redeposited fragments of volcanic rocks of various composition and synchronous pyroclastic material were identified in the sandstones. U–Pb isotope dating of detrital zircons and the obtained maximum depositional age made it possible to revise the stratigraphic volume of the Jurassic sediments exposed in the Central Zone and to limit it from the Upper Bajocian to the Tithonian. The immaturity of the composition and the absence of reliably dated Hettangian–Aalenian sediments indicate a new cycle of sedimentation and contradict the existence of a single Verkhoyansk passive margin in the Triassic–Jurassic.