Lithostratigraphic criteria of the polar moraine of Subarctic regions of European Russia and typomorphic features of garnets and zircon

The results of a comprehensive lithological study of the Upper Neopleistocene polar (Ostashkovo) moraine are considered: its textural, structural and mineral-petrographic features, as well as the chemical composition and typomorphism of garnets and zircons. Research was carried out to identify the lithostratigraphic criteria of this moraine and to substantiate the division and correlation of Quaternary sections. This moraine is widespread only in the extreme north of the Pechora Lowland, where it forms the relief of the day surface. Studied in the lower reaches of the Pechora and in the coastal outcrops of the Kuya, Chernaya, and Shapkina rivers. The moraine is characterized by a high content of pelitic fraction and has a finer composition than the Middle Neopleistocene moraines widely developed here. The mineralogical spectra of the moraine in the studied area are of the same type and are represented by epidote, garnets, amphiboles, siderite and pyrite. The total amounts of pyrite and siderite are increased to 20–35% with the permanent dominance of siderite over pyrite. A feature of the polar moraine is the presence in the petrographic spectrum of single fragments of the leading crinoid-bryozoan limestones of the Novaya Zemlya demolition area, and a very consistent orientation of elongated rock fragments from the north-northeast from the areas of Pai-Khoi–Novaya Zemlya and only the lower reaches of the river. Shapkina was overlapped by a glacial tongue from the northwest: from Fennoscandinavia and Northern Timan. The presence of garnets in the moraine is associated with their supply from metamorphic and certain types of igneous rocks. The predominant mass of zircon grains, in accordance with the ZrO2/HfO2 ratio, was formed in igneous rocks of basic and felsic compositions. Zircons from metamorphic rocks are contained in subordinate quantities.