Zonation of Redox Conditions during Crystallization of Cretaceous–Paleogene Igneous Rocks of the Sikhote-Alin Orogenic Belt (Russian Far East)

Abstract

The study of the magnetic susceptibility of igneous rocks from the Sikhote-Alin orogenic belt has shown that zones with the predominant development of ilmenite- or magnetite-series rocks formed during the Albian–Cenomanian magmatic stage. This zonation is independent of the petrochemical composition, type, and age of rocks and has been preserved until at least the Paleocene. It also shows no correlation with terranes. According to the authors, the redox zonation in the post-Cenomanian period was mainly determined by the granite-metamorphic layer of the new continental crust of the Sikhote-Alin orogen, which formed at the beginning of the Late Cretaceous.