Late Paleozoic – Mesozoic tectonic evolution of the Eastern Taimyr- Severnaya Zemlya Fold and Thrust Belt and adjoining Yenisey-Khatanga Depression

Abstract

Combined structural, thermochronological and geochronological studies were carried out to unravel the complex late Paleozoic – Mesozoic tectonic evolution of the eastern Taimyr – Severnaya Zemlya Fold and Thrust Belt, along with the adjoining Yenisey-Khatanga Depression and Olenek Fold Zone. New detailed field mapping, a fault and fold geometry and kinematic study, and paleostress reconstruction were undertaken for key areas within the Central and Southern Taimyr domains and the Olenek Fold Zone. Thirty seven samples were used for apatite fission track (AFT) analysis along with two samples for U-Pb zircon granite dating, and three samples for Ar-Ar metamorphic muscovite dating. The late Paleozoic (Early Carboniferous – Permian) tectonic event is recognized only in a relatively narrow zone including the Northern Taimyr Domain and part of the Central Taimyr Domain. It started in the Early Carboniferous (Visean) and is synchronous with the earliest stages of collision in the Uralian Orogen. Our results reveal a widespread distribution of latest Triassic – earliest Jurassic and Cretaceous deformations. The latest Triassic – earliest Jurassic tectonic event significantly overprinted the Northern and Central Taimyr domains and original unaltered late Paleozoic AFT ages are identified only locally. New completely reset AFT cooling ages group at 195-180 Ma, in reasonable agreement with structural data. Older Neoproterozoic and late Paleozoic Ar- Ar ages of metamorphic muscovite are retained, demonstrating that the dated rocks were not heated above 300 °C. An Early Cretaceous tectonic event is inferred from both the structural study and ca. 115–125 Ma AFT cooling ages, and is most widespread in the Southern Taimyr Domain, Olenek Fold Zone and adjoining parts of the Yenisey-Khatanga Depression, modifying older geological structures. A younger Late Cretaceous tectonic event at ca. 100-60 Ma is also inferred from AFT cooling ages, but its distribution is poorly constrained. Our study reveals that the distribution of late Mesozoic tectonic events has been significantly underestimated in previous structural studies of the region. The latest Triassic – earliest Jurassic and Cretaceous tectonic events are easily correlated with those in the Pai-Khoi – Novaya Zemlya and northern Verkhoyansk fold and thrust belts.