Age and Tectonic Position of the Ulkan Group, the Stratotype of the Upper Karelian in Eastern Siberia and the Far East

摘要

Determination of the age boundaries of the Lower Proterozoic and Riphean is an important problem of stratigraphic subdivision of the Siberian Precambrian. Within Eastern Siberia and the Far East, the Northwestern Transbaikalian and the Uchur-Maya regions are regarded as the most favorable areas for this problem to be solved. In these regions, there are the most well represented Upper Lower Proterozoic (Pre-Riphean) (Akitkan and Ulkan Groups) and Riphean sequences. In [1] these groups are referred to the Upper Karelian and regarded as molasses, which were formed during the Svecokarelian tectonomagmatic cycle.