U–Pb AGE OF DETRITAL ZIRCON GRAINS FROM MIDDLE JURASSIC SANDSTONES OF THE NORTHEASTERN FLANK OF THE NAGONDZHA TERRANE (ULAKHAN-SIS RIDGE, SAKHA REPUBLIC)

U–Pb (LA-ICP-MS) dating of detrital zircon grains from the Middle Jurassic deposits of the northeastern flank of the Nagondzha Terrane was carried out. The sandstones contain zircon grains from Archean to Middle Jurassic. The weighted weighted average age of the youngest zircon population is 167.6±1.2 million years (Bajocian-Bathonian). The intensity of the 168 Ma peaks and the presence of synchronous pyroclastic material in the deposits suggest the proximity of active volcanic centers to the sedimentation area in the Bajocian-Bathonian. This confirms the existence of island volcanic arc on the Omulevka microcontinent in the Middle Jurassic. Volcanic arc supplied elastogenic material to the eastern part of the Oymyakon paleobasin. Other sources of detrital material included Paleozoic volcanic-sedimentary rocks of the basement of this arc, as well as Precambrian and Paleozoic metamorphic, igneous and sedimentary rocks developed within the Prikolyma and Omolon Terranes. The main difference between the studied sandstones and the Middle Jurassic terrigenous rocks of the Polousnyi Terrane is the presence of a significant number of zircon grains with Meso-Neoproterozoic ages, probably redeposited from the Paleozoic terrigenous strata of the Omulevka and Prikolyma Terranes.