SOUTH ANYUI SUTURE, NORTHEAST ARCTIC RUSSIA: FACTS AND PROBLEMS

Abstract

The South Anyui suture zone extends from the eastern part of the Laptev Sea into western Chukotka (northeastern Arctic Russia) and is everywhere marked by Mesozoic terrigenous turbidite and fragments of ophiolitic sequences. Ophiolitic sequences of both Paleozoic and Mesozoic age are believed to be present. The units flanking the suture are known to host suprasubduction-zone arc complexes of late Paleozoic-Late Jurassic age on the south and of Late Jurassic-Early Cretaceous age on the north. The Paleozoic Anyui oceanic basin is proposed to have been connected with the Taimyr and Polar Urals ocean basins. The relationship of the Anyui ocean basin with the paleo-Pacific remains debatable. In the Late Jurassic-Early Cretaceous (or, possibly, beginning in the late Paleozoic), the South Anyui basin became separated from the Pacific by a convergent boundary. The accretionary mélange and approximately coeval suprasubduction-zone complexes are regarded as indicators of convergent plate motion and boundaries between the oceanic plates of the South Anyui basin and the Siberian continent, and the Chukotka microcontinent. Four principal stages of deformation are distinguished in the South Anyui zone (Natal'in, 1984). The first two stages gave rise to fold and thrust-type structures. The two later stages involved strike-slip faulting. The most important interaction between the Chukotka microcontinent and Siberia during latest Jurassic and Early Cretaceous time was likely related to oblique collision between the two continental masses that involved lengthwise dextral strike-slip motion along the South Anyui suture.