The article reviews shallow (engineering geological, stratigraphic and prospecting) drilling in different years and using different methods. In the Arctic zone under conditions of lower temperatures and great ice cover of seas, shallow drilling was usually carried out from the shore ice in the regions of the Taimyr and Chukotka, and in the straits of the Novosibirsk Islands. Drilling from ice was implemented in the late spring–early summer at the convenient thickness and stability of the ice cover. Two wells were drilled off a drilling ship in the Laptev Sea. Moreover, two drilling expeditions were undertaken to the Laptev Sea and Chukchi Sea; those holes were drilling from non-drilling ships, using a multi-trip drilling facility. Shallow drilling enables solving important problems connected with research and production, namely, stratigraphic, paleographic, mapping and prospecting research of the upper sedimentary cover. Since the 1970s such problems were handled using various drilling techniques. Nearby the Taimyr Peninsula, drilling operations were concentrated Pyasina Bay, Mikhailov Peninsula, Fjord Gafner bay and in the Theresa Clavenes Bay. In the Laptev Sea, drilling was implemented at the Cape Mamontov Klyk, at the Lena River estuary, in the Buor-Khaya Bay and northwest of the Kotelny Island. Prospecting drilling on local islands, in bays and straits enabled comprehensive investigation in the zones of the Novosibirsk Islands. The coastal areas of the East Siberian Sea and Chukchi Sea were investigated in prospecting drilling off ice. In the Long Strait between Chukotka and the Wrangel Island, two holes were drilled from a deep-sea tug. It was determined that the upper sedimentary cover layers belong to the Paleogene–Neogene period in the straits of the Novosibirsk Islands and in shallow water of the East Siberian Sea, to the Pliocene–Quaternary period on the soundings of the Chukchi Sea and in the straits and fjords of the Taimyr, and to the Late Pleistocene–Holocene system in the Laptev Sea. Further drilling activities are aimed to find shallow placers, to study degradation of submarine permafrost and to determine gas content of sedimentary deposits. The drilling results will be used in reconstruction of the Late Cenozoic Paleogeography in the Arctic zone.The study was supported by the Russian Foundation for Basic Research, Grant No. 18-5-60004.

For the first time tectonic reconstructions was carried out along the entire seismic dataset, including both Russian and international seismic lines. Based on the analysis of the sedimentary cover of the Eurasian Basin (Arctic Ocean), four stages of evolution of the sedimentation system were identified. During the first, Cretaceous–Paleocene stage, vast axisymmetric epicontinental Amundsen and Nansen paleo basins were formed on the shoulders of the continental rift. Similar rifting environments of the second half of the Cretaceous were recorded along the entire periphery of the Arctic Ocean from Greenland and Svalbard to the Chukchi Borderland. The second (Eocene) stage was characterized by gradual expansion of the sedimentary basin up to its present-day size, caused by accretion of oceanic crust in the Gakkel Ridge and seafloor spreading. The Eurican orogeny, which formed dextral De-Geer transform zone, was suggested as a main tectonic driver of the spreading stage. The third (Oligocene‒Miocene) stage corresponds to the accumulation of undisturbed veneer of hemipelagic sediments of 300‒600 meter thick, which covered the entire Eurasian Basin. Accumulation of undisturbed sediment sequence throughout the Eurasian Basin indicates the cessation of seafloor spreading in the Gakkel Ridge and the establishment of a tectonic dormancy regime untill the neotectonic stage onset. The similar tectonic regime is recorded along the entire periphery of the Arctic Basin. The resumption of the seafloor spreading in the Gakkel Ridge occurred during the fourth (Pliocene‒Quaternary) stage. We suggest that the re-spreading process in the Eurasian basin has tectonically been triggered by the activation of the similar process in the Norwegian‒Greenland Basin. Propagation of the tectonic stresses along the Gakkel Ridge toward the Siberian segment of the Eurasian Basin explains both the distinct morphological segmentation of the Gakkel Ridge into the Siberian and Atlantic segments, and the anomalously high tectonic, volcanic and hydrothermal activity of the Gakkel Ridge.

Apparent variations in the morphology of the Lomonosov Ridge and its along-strike segmentation are caused by the heterogeneity of the basement. Based on the morphological diversity, we divide the Lomonosov Ridge into three segments: Siberian, Central and North American. New petrographic and geochronological data from the rock clasts sampled in the "Arctika-2007-1" expedition, are integrated with seismic and relevant mineralogical, petrographic and isotopic data. Recovered fragments of the high-grade metamorphic and siliciclastic rocks are attributed to the bedrock of the Siberian and Central Segments of the Lomonosov Ridge respectively. The mineralogical and isotopic analysis of detrital zircons from Neoproterozoic arkose defines the Grenvillian age for the basement of the Siberian Segment of the Lomonosov Ridge. The U-Pb dating of the metamorphic zircons from gneisses and schists suggests that Timanian crystalline basement of the Central Segment was affected by an upper-Ordivician (similar to 450 Ma) felsic magmatism, followed by the mid- to high-grade Caledonian tectonometamorphic event (similar to 400 Ma). The Central Segment is therefore inferred to be a frontal part of Caledonian convergent shear and fold zone. Caledonian deformation front is suggested between the northeastern and southwestern islands of De Long archipelago. Northward from the shelf break, the orogenic front is expected between the Geophysicists Spur and the main horst of the Siberian Segment. Within the Central Segment the Caledonian deformation front is inferred to stretch along the western flank of the Lomonosov Ridge.

Fossiliferous carbonate rocks dredged during the "Arctic-2012" cruise on the Mendeleev Rise (eastern Arctic) provide proof of the presence of Upper Silurian(?)-Middle Devonian, Famennian-Tournaisian, Bashkirian-Kasimovian, Gshelian-lower Asselian(?) and Kungurian-Kazanian carbonate deposits. The wide spectrum of facies includes deposits of both photic zone (with fusulinids, algae, relicts of microbial and coral reefs) and deeper dysphotic areas (with trilobites, deep-water tentaculitids and ostracods). The results obtained suggest that there were at least three periods of carbonate platform sedimentation during the latest Silurian(?) to Permian. The Late Silurian?-Devonian biota do not show biogeographical differentiation, but rather are distributed globally. Shallow-water foraminifera and some algae of early Pennsylvanian-basal Cisuralian age belong to the warm-water province. These forms are unknown in the Moscovian-Permian of the Boreal Realm (Taimyr, New Siberian Islands, Verkhoyanie, Omolon Massif) but are typical for Alaska and Arctic Canada, Wrangel Island, Chukotka, Polar Urals and Svalbard. The disappearance of warm-water biota during late Artinskian-Kungurian times led to a subsequent predominance of smaller foraminifera: this assemblage with Protonodosaria is widely distributed in Permian deposits of Novaya Zemlya, Urals, Barents Sea and the eastern Arctic. The warm-water Bashkirian-Asselian biota suggests that the Mendeleev-Chukotka-Wrangel block was a low latitude shallow basin with predominant carbonate sedimentation, being part of the Arctida supercontinent, connected temporarily with the eastern margin of Laurasia (Chukcha-Alaska block).

Geological and geophysical studies undertaken during the Russian Arktika-2012 Expedition of 2012 produced evidence of basement outcrops on the steep slopes of the Mendeleev Rise seamounts. Observations of the outcrops from research submarines showed that part of the steep slopes interpreted as basement outcrops based on seismic data were overlain by a light sediment cover. The actual areas of the basement outcrops are therefore much less than indicated by the seismic data alone. The outcrops found are of 5–10 to 100–200 m and are often stretched along some hypsometric level or arranged obliquely, crossing a slope at an angle to the horizon. The rocks are massive and layered, often strongly weathered, cavernous, with visible fissures and extended by dislocations.

The available seismic and magnetic data show the Gakkel Ridge rift zone consisting of the Atlantic and Siberian segments divided by a tectonic suture at 70° E. The two segments have had different histories recorded in their sedimentary cover. Apart from the difference in its morphology, the Siberian segment differs from the Atlantic one in the existence of a series of deposition centers, which might represent a vast Paleogenic basin that formed prior to the Gakkel Ridge. The simple model of North Atlantic spreading fails to explain the long and complex history of the Gakkel Ridge rift and the existence of the depocenters. The particular structure of this zone might have resulted from the growth of rift mountains by accretion of magmatic material during the Paleogene, without significant sea floor spreading.

Using high-resolution seismic data, this study aims at investigating the evolution and morphological diversity of subsea permafrost features on the eastern Laptev Sea shelf, Arctic Siberia. Several seismic facies were recognized. These relate to the major environmental changes, which affected the Laptev Sea area before, during, and after the last global transgression. Because this shallow shelf was part of the Beringian landmass, we consider a prominent subsurface seismic basal reflector as the top of the former terrestrial permafrost table. Five zones differing in geometry, reflection patterns, depths, and continuity of the permafrost top are identified. Where visible, the upper 70 m of the sediments consists of epigenetically and syngenetically frozen ice-poor sandy deposits at the base, possibly of early last glacial age, marine isotope stages (MIS) 5 and 4. These are followed by late glacial, ice-rich facies interpreted to be MIS 3 to 2. The early Holocene (MIS 1) features well-stratified lagoonal and taberal deposits. As verified by radiocarbon-dated sediment cores, these deposits are overlain by middle to late Holocene sediments with an increasingly marine signature.

Mineralogical-petrographic and isotope-geochemical studies were carried out for basic and intermediate magmatic rocks derived by deep-water drilling and dredging at the test sites from 79.02° N to 83.09° N, Arctic Ocean (AO), during expedition “Arktika-2012” with the icebreaker Kapitan Desnitsyn. Volcanic bedrock samples derived from the drill holes at the foot of the Mendeleev Rise are grouped into the low- and moderate alkali rocks, showing narrow ranges in the initial Nd (ɛNd(T) from +4.3 to +7.0) and Sr (87Sr/86Sr from 0.70365 to 0.70495) isotope ratios, and correspond to the volcanic rocks of the oceanic islands and rises in the discriminant isotope and geochemical diagrams. Gabbro-dolerite samples dredged from the slopes of the Mendeleev Rise are grouped into the low-alkali field and show wide variations in Nd (ɛNd from −33.1 to +2.9) and Sr (87Sr/86Sr from 0.7050 to 0.7233) isotope compositions, being similar to the Siberian flood basalts and, possibly, other rocks of continental genesis.

Two sediment cores retrieved from the southern Lomonosov Ridge (LR) in 2007 (core ALR07-26C from the top of the ridge, water depth 1359 m, and core ALR07-15C from the base of Geophysicists’ Spur, water depth 2500 m) were investigated for lithology (wt % > 63 μm, terrigenous lithic grains >500 μm) and microfossils. Prominent peaks of coarse-grained material in ALR07-26C represented largely by quartz and clastic rocks are regarded as inputs of ice and, especially, iceberg-rafted debris (IRD) of Eurasian origin. In accordance with previously obtained evidence from age-constrained cores from the central LR, the highest peak 4 is correlated with the MIS 6–5 boundary and the disintegration of the Saalian ice sheet. The three younger IRD peaks are provisionally correlated with the MIS 5–4, MIS 4–3, and MIS 2–1 boundaries, respectively. Small peaks of coarse-grained material in ALR07-15C dominated by various rocks in contrast represent local material transported by downslope slides mixed with some IRD. No calcareous microfossils occur in the cores, but only agglutinated benthic foraminifers are found. In ALR07-26C, they correlate with IRD-rich layers, which correspond to glacial terminations with more open-sea ice conditions and, probably, higher productivity in the sea-ice marginal zone. The Cyclammina-dominated assemblage in ALR07-26C below IRD peak 4 supports the proposed age estimate for this peak (MIS 6–5), as similar foraminiferal assemblages in other LR cores are recorded in sediments of MIS 7–9 and older. Younger assemblages show a transition from a Recurvoides-dominated assemblage in the early Late Pleistocene to a more “oligotrophic” recent assemblage with a predominance of Reophax and Rhabdammina.