First Data on the Nature and Age of the Protolith of High-Pressure Tectonites of Yenisei Ridge: A Link to the Early Stage of Formation of the Paleoasian Ocean

Resumo

The petrogeochemical characteristics of high-pressure mafic tectonites from the Yenisei suture zone of Yenisei Ridge indicate that N-MORB and E-MORB with an age of 701.6 ± 8.4 Ma were their protolith. The formation of N-MORB with the more primitive chemical composition occurred at the initial stages of spreading, when the upper horizons of the depleted mantle were molten. The high-Ti basalt was formed as the product of melting of the enriched mantle substrate at the later stages of spreading. These events are related to the early stage in the evolution of the Paleoasian Ocean on the western margin of the Siberian Craton.