Formations of the carboniferous-lower Permian carbonate deposits of the Upper Pechora basin (Northern Urals)

The Upper Pechora basin is part of the northeastrn margin of the European Platform. In the Paleozoic, it was located within the carbonate shelf of the passive continental margin. According to A. I. Eliseev, Visean terrrigenous-carbonate (platamovy type) and Upper Visean-Lower Artinskian carbonate (kaleydovy type) formations occupy the upper part of the final sedimentation cycle of the formations row. According to new data, the history of the geological development of the Upper Pechora basin of the Late Visean-Asselian period has significant differences. Four types can be distinguished in the structure of sediments according to the composition of rocks: siliceous-clay-limestone, limestone, dolomite-limestone, siliceous-limestone. They were formed during three stages respective to the time of formation of three transgressive-regressive cyclites: the Visean-Serpukhovian, Bashkirian-Moscovian, Upper Carboniferous-Lower Permian. The studied deposits are divided into lithological complexes: siliceous-clay-carbonate of open sea (Tulian), siliceous-carbonate of open sea (Aleksinian-Early Mikhailovian, Bashkirian-Early Moscovian, Kasimovian-Midle Gzhelian), carbonate of shallow-shallow (Late Mikhailovian-Protvinian, Moscovian), and also the Late Gzhelian-Asselian shallow-depression (siliceous-limestone, limestone, clay-limestone). Lithological complexes, formed in open-sea conditions, belong to formations from the platamovy type and in shallow-shallow conditions - to formations from the kaleidovy type (by Eliseev, 2008).