Sedimentation Conditions and Provenance Composition of the Upper Jurassic–Lower Cretaceous Deposits of the Upper Pegtymel Depression, Chukotka Terrane

Resumo

The deposits of the Imlekin Formation of the Upper Pegtymel depression were formed in the southern margin of the Chukotka Terrane synchronously with accretion of the Kulpolney island arc to the Chukotka–Arctic Alaska microplate. The sedimentological structural features of the Upper Jurassic–Lower Cretaceous sections indicate their accumulation within various parts of submarine fans of a shallow marine basin. The submarine slump origin of the boulder–pebble (tillite-like) conglomerates is substantiated. The petrographic, geochemical, and geochronological methods identified two dominant provenances: Triassic clastic rocks and Volgian suprasubduction volcanic rocks. The Middle Volgian–Early Berriasian age of the Imlekin Formation is specified. The geodynamic model proposed explains the change of the sources and direction of the sediment transport in the Volgian.