Geology of Wrangel Island, between Chukchi and East Siberian seas, northeastern Russia

Abstract

The oldest unit on Wrangel Island is the Upper Proterozoic Wrangel Complex, a 2000+ m succession of volcanic and clastic sedimentary rocks with small mafic and granitic intrusives and U-Pb crystallization ages of 0.63 to 0.70 Ga. The oldest Paleozoic unit is a 700 m succession of Upper Silurian and Lower Devonian clastic and carbonate strata. These strata are overlain in ascending order by: 1200 m of Devonian clastic rocks; 350 m of Lower Carboniferous clastic rocks, with conglomerate, carbonate and gypsum; 1400 m of Carboniferous carbonate with slate and bioherms; a 750 m thick unit of Permian slate and limestone, locally with olistostrome and breccia; 800 to 1500 m of Triassic flysch; and lastly, tens of metres of undeformed Tertiary and Quaternary clastics. All rock units of Proterozoic to Triassic age were pentratively deformed into north-verging structures, and metamorphosed to greenschist facies, during the Mesozoic Chukotkan Orogeny (Middle Jurassic to Early Cretaceous). Some aspects of Wrangel Island's tectonic history in the circum-Canada Basin are peculiar. The most important are: Late Proterozoic magmatism; inferred latest Proterozoicþearly Paleozoic orogenesis; Triassic flysch; Chukotkan deformation; and late Early Cretaceous overlap of all northeastern Russian terranes by the Upper Cretaceous OkhotskþChukotsk volcanic belt.