FORMATION SETTING OF EARLY MESOZOIC BASALTS OF THE RUSSIAN FAR EAST: ACCRETION OF THE PACIFIC GUYOTS OR EPICONTINENTAL RIFTING?

Abstract

The formation setting and origin of alkali basalts hosted in Mesozoic siliceous–terrigenous rocks of the Russian Far East remain controversial issues. Some geologists believe that these basalts are remains of Pacific guyots in accreted oceanic terranes. Based on the presence of such basalts, the host fold-thrust structures are interpreted as open oceanic deposits transported over many hundreds of kilometers. Subsequently, they were adjoined to the continent as accretionary prisms in the Jurassic, Jurassic–Early Cretaceous, and Early Cretaceous. According to another concept, the Mesozoic alkali basalts are related to volcanism in the epicontinental basins (rift-grabens).