## 3 Results and Discussion  
Bivalves are an informative fossil material that is present in a subfossil form in marine sediments. Malacofauna is a subtle indicator that relatively quickly and accurately captures and reflects changes in individual abiotic parameters of the paleogeographic setting. The study of fossil shells, and their enclosing deposits, as paleomarkers characterizing the conditions of sedimentation in the Pechora paleobasin will supplement the existing theoretical ideas about the development of the territory at the stage of climatic optimums of the Late Quaternary period. According to our hypothesis, the elemental composition and variations in the stable d\({}^{18}\)O and d\({}^{13}\)C isotopes of fossil shells will be consistent with previously established global climate fluctuations in certain periods of the Pleistocene and Holocene. To date, the correlation of Pleistocene and Holocene deposits of the Pechora paleobasin exists. The reference sections Vastyanskiy Kon' (Figure 3), Khongurei (Figures 4 and 5), Pyoza area (Bychye) (Figure 6), and Sula (Figure 7) were studied and described [54; 55; 56; 57]. The lower marine part of the Vastyansky Kon' outcrop is a clay strata. Dark grey, sandy clay-siltstones and clays, in some places layered, in places with lenses of grey medium-grained sand with gravel and pebbles, emerge above the water's edge. Here, in the lower part of the outcrop of the Vastyansky Kon', shells of mollusks are found. From about 7 m above the water's edge, the clays become more uniform, and sometimes layering is visible, expressed due to interlayers of more silty material. At a height of 24 to 26 m, interlayers of sand with pebbles and shells appear in the clayey strata. The overlying clay sequence is also characterized by faunistic remains; a clear ferruginous contact separates it from the sands. The middle part of the Vastyansky Kon' section is represented by a sequence of alluvial sands, the lowest part of which is a regressive marine member. Shells of boreal mollusks were previously found in it. In [58], an attempt was made to create a high-quality 3D outcrop model using a drone. The thickness of the sands has an extremely uneven thickness--from 15 to 55 m and more [39] (Figure 6). With their foundations, clay blocks go under the river edge Pechora, and their sharp peaks rise above it to a height of 20 to 50 m [3]. Sand packs in the outcrop Vastyansky Kon' were dated: 24,790 \(\pm\) 500, 26,800 \(\pm\) 3 70, 28,380 \(\pm\) 270, 28,675 \(\pm\) 300, and 29,470 \(\pm\) 450 years old (Figure 3b, geological structure). However, the results of these radiocarbon analyses are older, because samples from peatlands were taken after the Novaya Zemlya explosions [59]. Comprehensive studies of moraine horizons in coastal outcrops made it possible to correlate them in the extreme northeast of the European Subarctic of Russia [39] (according to Figure 2). The identified three horizons of moraines differ in lithological features. Reliable and regionally consistent lithological correlatives are the orientation of elongated rock fragments and the presence of guide boulders [39]. In the Pechora Lowland, sediments of the Late Pleistocene boreal sea include outcrops of marine sediments at the base of the sections Vastyansky Kon', Khongurey, in a series of sections in the valley of the river Sula [54; 55; 56; 60] (according to Figures 2-4, 6 and 7). In all these points, only one relief-forming moraine occurs above the marine deposits. Its late Valdai age was proved not only by a series of radiocarbon dates obtained for the deposits, but also by the results of kinetostragraphic studies [3]. The macrofauna of the lower part of the Rodionovo deposits in the Vastyansky Kon' section includes arctic species such as _Macoma calcarea_, _Hietella arctica_, typical arctic species _Portlandia arctica_, _Yoldiella lenticula_, _Yoldia hyperborean_, _Propeamussium groenlandicum_, and _Cerastoderma ciliatum_.