What is the age of the Udzhapa leorift?: U-Pb age of detrital zircons from Udzha basin terrigenous succession, northern Siberia

Abstract

The Udzha paleorift is located between the Anabar and Olenek rivers and is a key structure indicative of the breakup of the Nuna supercontinent. However, the age of initiation and duration of paleorift activity is not defined nowadays. Here we present new U-Pb data for detrital zircons from two terrigenous and volcanic-sedimentary successions of the Udzha sedimentary basin (Unguokhtakh and Udzha Fm), from terrigenous rocks overlying the Udzha basin (Tomtor Fm), and from the sandstone of the lower Mesoproterozoic Mukun Group in the northwest part of Anabar region. The dating results show that sedimentation in the Udzha rift basin began later than ca 1459 Ma, and the duration of the rift activity is estimated as not longer than 73 My. The Udzha rift basin was an isolated basin in the northern part of Siberia, and detrital material came from local sources. A previously unknown source for tuff-sandstone of Unguokhtah Formation with an age of 1850 Ma has been identified, which corresponds by age to the Paleoproterozoic post-orogenic magmatism of the Siberian Craton. In the Neoproterozoic, detrital material of the Tomtor Fm was supplied from the northeast, and the sources were igneous suites of active margin or collision settings. The maximum depositional age of Tomtor Fm is estimated as 565 Ma on the youngest zircon population, which suggests an over 800 Ma gap in sedimentation in northern Siberia in Meso- Neoproterozoic.