The First Data on Mesoproterozoic Tectonic Events in the Geological History of the South Yenisei Ridge

摘要

Special attention in scientific publications of recent years has been paid to shear zones of continental margins, which are the areas of bulk fragile and plastic flows of rock masses localized along the narrow linear structures of the Earth's crust. These publications demonstrate some characteristic effects accompanying intense shear deformations during tectogene-sis. Despite increasing interest in these problems, one of the least studied is the problem of the role of syn-shear metamorphic processes in the formation of the foldbelt structure. The significance of these processes for reconstruction of the evolution of orogens is strongly underestimated. In this paper we consider new geochronological and petrological data for metapelites of the South Yenisei ridge with different ages, T-P parameters of metamorphism, and intensities of deformations. These data allowed us to distinguish the Mesoproterozoic stage in the tectonic history of the region for the first time. In addition to the solution of regional problems, these results are important for correlation of regional peculiarities with global geological processes, in particular, entrance of the Siberian Craton into the composition of the Nuna and Rodinia supercontinents.