Herein we report the results of LA-ICP-MS dating of detrital zircons from eight stratigraphic levels of the Proterozoic section of the Igarka uplift (northwestern Siberian Platform). The age spectra include the Meso- and Neoarchean (3100–2600 Ma), Paleoproterozoic (2100–1700 Ma) and Neoproterozoic (1000–600 Ma) ages. However, the age distribution drastically varies among the samples. The Neoproterozoic zircons, associated with the hypothetic orogenic belt at the platform periphery, dominate in the lowstand system-tract continental and marginal marine strata (Gubinskaya, basal Chernaya Rechka, and Izluchina formations). In contrast, the zircons in the Riphean and Vendian marine strata (Bezymyanny, Ludy, Korablik, and Sukharikha formations) mostly originate from erosion of the crystalline basement of the Siberian Platform. The concordant mafic bodies in the Upper Riphean (Criogenian) Gubinskaya formation contain the concordant cluster of zircons of 835±4 Ma. It contradicts with the maximum deposition age of 716±10 Ma of the host strata, hence the zircons in the mafic bodies supposedly comprise xenocrysts.

The article unravels a confusing history of ideas about the age of the Garevka granite pluton, which is considered as a reference object for the Precambrian of the Yenisei ridge. Initially, the Paleoproterozoic (1750 Ma) age of granite was determined by M.I. Volobuev and co-authors half a century ago using Pb/U isotope analyses of zircons and orthites. This dating is widely used up to recent to substantiate the Early Precambrian age of the metamorphic rocks of the Trans-Angara region. In 2003, V.A. Vernikovsky and his colleagues published data on the Neoproterozoic (752±3 Ma) age of the massif, obtained with modern technique of isotopic analysis. However, some of experts on the geology of the Yenisei ridge considered both isotopic ages correct, believing that the eastern part of the massif comprises Paleoproterozoic gneissic granite. Our investigation revealed the following: V.A. Vernikovsky and M.I. Volobuev indeed have collected their granite samples at the western and at the eastern parts of the pluton correspondingly. Krasnoyarsk geologists map the Garevka pluton as part of the Neoproterozoic Glushikha granite suite, but use to apply its Paleoproterozoic dating to substantiate the early Precambrian age of the host rocks. M.I. Volobuev obtained ten mainly discordant Pb/U analyses of the Garevka granites, and six of them form an explicable combination consistent with the age of 1750 Ma. The only concordant analysis with a known sampling point is decisive for the entire system. Thus, to fix the problem, it was necessary to reproduce this analysis using modern isotope techniques. We have dated (SHRIMP) a granite sample collected at the same point. In addition, three more samples from different parts of the massif were analysed to exclude the possible presence of ancient domains in it. The isotope ratios of all analysed zircons form a concordant cluster with an age of 762±7 Ma. The Garevka pluton comprises a separate mappable body composed of biotite leucogranites with fluorite. Granites do not replace some older rocks, but crystallized from the melt, ascended from deep crust. The question about possible Paleoproterozoic age of the Garevka granite pluton or any part of it is closed. Ideas about the wide distribution of Archean and Paleoproterozoic gneisses in the Trans-Angara region require additional geochronological verification. To date, the presence of such rocks has been reliably established here only at two local points.

Northwestern segment of the Precambrian Yenisei Ridge contains ophiolite and is known in literature as the Isakovka Terrane or Isakovka domain. We suggest to divide it into two belts: Kiselikha (western) and Torzhikha (eastern), which differed in geodynamic regime during the Late Neoproterozoic (750–600 Ma). It is believed that the Kiselikha belt is mostly composed of volcanic rocks erupted at island arc setting in the second half of the Neoproterozoic, and that collision of this arc with the Siberian Continent formed the Yenisei Ridge orogen. This idea has not been sufficiently supported by geological and geochronological data. Dating of four detrital zircons samples extracted from sedimentary and volcanic-sedimentary rocks in the southern part of the belt revealed that the sampled strata belong to three different Precambrian levels: the Mesoproterozoic, the mid-Neoproterozoic (800–750 Ma), and the end of the Neoproterozoic (620–600 Ma). Thus the authorized stratigraphic layout of the belt, as well as its proposed island-arc origin requires revision. By this paper we announce the identification of the Kiselikha Terrane , which was a part of active margin of the Siberian Paleocontinent at the beginning of the Neoproterozoic. Approximately in the middle of the Neoproterozoic, this block was rifted off Siberia and further evolved as a microcontinent bounded by an active margin from the outer side.

Several fold belts approach the Laptev Sea from different sides, and their tracing through the shelf is ambiguous. The only way to reconcile geological facts is to suggest that the Verkhoyansk–Chukotka fold belt occupies most of the Laptev Sea shelf in the form of an orocline folded in two. The Verkhoyansk fold belt is composed mainly of deformed sediments accumulated during the late Paleozoic and early Mesozoic on the passive continental margin. The oroclinal structural model may be validated by tracing the edge of the continental shelf imprinted in Permian rocks, which are the only stratigraphic level available all over the sea periphery. This has been done for the southwestern, western, and eastern shores of the Laptev Sea. For the last locality, i.e., for the New Siberian Islands, the initiation and evolution of the late Paleozoic rifted continental margin facing the Laptev Sea was also outlined. Following the oroclinal model, the tectonic partitioning of Taimyr and Severnaya Zemlya is tentatively traced to the opposite side of the Laptev Sea. We assert that three Taimyr belts (South, Central, and North) are not separated by Paleozoic or Mesozoic sutures and are distinguishable by different composition and depositional settings of lower Paleozoic sedimentary rocks formed on the marginal part of the Siberian continent. In particular, the North Taimyr belt is interpreted as a foreland basin developed during the collision of Siberia with Baltica in the late Ediacaran – Early Cambrian. Ordovician volcanic and plutonic belt in the eastern October Revolution Island we assume to be a riftogenic one, which is coeval with similar igneous occurrences of De Long Islands on the opposite side of the Laptev Sea. The Ordovician rifting could have initiated the opening of the Taimyr branch of the Ural Ocean, which, however, did not leave behind any material evidence. The most probable position of the suture is the Shokalsky Strait (separating Bolshevik and October Revolution Islands) and the shelf area along its strike. The collision of Siberia with the Kara block of Baltica occurred once again in the Late Paleozoic. Three fold belts largely shape the modern structure of the Laptev Sea region: the late Paleozoic North Taimyr belt, the Late Triassic South Taimyr one, and the Late Jurassic-Neocomian Verkhoyansk. All above orogenic belts were formed not at the boundaries of lithospheric plates but mainly at sites of extended and thinned lithosphere. These were the foreland basins of previous orogenies for the first two belts; and rifted passive continental margin for the last one. Revealed recent structure of the Laptev Sea region opens up the prospect of restoring pre-Cretaceous paleogeography when the relative position of continental blocks was quite different.

Sedimentological features of the Upper Cambrian–Middle Ordovician rocks exposed in eastern Taimyr in the Faddey Gulf area are discussed. The studied sections belong to the transitional facies zone located between the carbonate platform (Siberian Platform continuation) in the south and a relatively deep-water basin in the north. The studied deposits compose a genetically coherent sequence formed in the distal zone of the siliciclastic–carbonate ramp at a depth exceeding the storm wave base. The lower (Upper Cambrian–lowermost Ordovician) part of the sequence is represented by limestones, dolomitized carbonate siltstones, and sandstones with shale layers. The upper (Lower–Middle Ordovician) part of the studied interval is dominated by shales with thin layers of carbonate siltstones. The carbonate detritus was sourced from a shallow-water shelf located south of the studied sections. The siliciclastic admixture in carbonate siltstones and sandstones was sourced from an island in the northern part of the modern Siberian Platform. The sandy material was transported by storm bottom currents; the fine-grained particles, by surface currents and winds as particulates and suspension clouds in the bottom water. Carbonate sandstones with the typical turbidite sedimentary structures, common in the lower part of the section, were deposited by turbidity currents initiated by storms. At that time, a prominent break likely existed in the ramp profile. The predominant NE orientation of flute casts indicates the alongslope (or along the trough axis) transport of material by bottom currents. The ramp topography was leveled in the second half of the Early Ordovician and in the Middle Ordovician.

Permian marine bivalves of the Pronchishchev Ridge (North Siberia) were systematically studied for the first time.. The presence of the Middle and Upper Permian with five biostratigraphic levels was established based on fossil findings. In the Middle Permian, these are the bivalve Kolymia inoceramiformis–K. plicata (undivided) and Kolymia multiformis zones, and in the Upper Permian—the Maitaia bella Zone (Beds with Phestia ex gr. ovata), Maitaia belliformis Zone, and Intomodesma costatum Zone. The bivalve assemblages from the Middle and the lower Upper Permian (up to the Intomodesma costatum Zone) are similar in their taxonomic composition to those from the Western and Northern Verkhoyansk regions. The uppermost Permian fossil assemblages (Intomodesma costatum Zone) are different. They are represented almost exclusively by monotaxonic aggregations of the large pectinoid Streblopteria rotunda (Lutkevich et Lobanova) and rather rare representatives of the genus Intomodesma. The marine basin of the present-day Pronchishchev Ridge had stable links with the Verkhoyansk basin throughout almost the entire Permian. This basin was very shallow and may have experienced episodes of desalination. In the end of the Permian, the paleogeographic situation changed, and the connection between the Pronchishchev Ridge and the East Taimyr basins became more pronounced. Most characteristic bivalve species are illustrated, and a new species Kolymia rutskovi Biakov, sp. nov. is described.

Abstract Bennett Island stands alone in a remote part of the Arctic and information on its geology is essential to ascertain relations with other terranes in order to restore the early Palaeozoic Arctic palaeogeography. Lower Palaeozoic sedimentary rocks throughout the island were studied thoroughly for the first time. The Ordovician section (> 1.1 km thick) comprises three units: Tremadocian, lowest Floian black shale (130–140 m); Floian, lower Dapingian carbonate turbidite (> 250 m); and Dapingian, lower Darriwilian siliciclastic turbidite (> 730 m). Ordovician deposits conformably overlie Cambrian rocks deposited within the Siberian shelf, as shown earlier. Most of the Ordovician succession was formed in a deep trough that received carbonate debris from a nearby carbonate platform and silicate material from a distant landmass located to the NE (present coordinates). The Bennett Island Ordovician rocks have much in common with those of both the Central and Northern Taimyr belts. It could be tentatively suggested that both belts merged at their eastern continuation in the vicinity of De Long Islands. The whole system probably extends further eastwards. The Ordovician facies patterns and faunal assemblages in the New Siberian Islands are notably similar to those of northwestern Alaska, where the same lateral transition from turbidites to shelf limestones was reported.

The information on the Late Palaeozoic deposits of the New Siberian Islands is essential to clarify the palaeogeography of the surrounding Arctic Region and to quest the original location of the New Siberian continental block prior to the Amerasian ocean opening. The best Upper Palaeozoic section of the islands, located in the western part of the Kotel’ny Island (Tas-Ary Peninsula), was examined in detail. The studied rocks characterize a transitional facial zone between the northeastern shallow-water (central areas of the Kotel’ny Island) and the southwestern deep-water ones (Bel’kov Island). The stratigraphy of the Carboniferous and partly Permian strata was specified by the study of four fauna groups, detrital zircon dating, and structure interpretation. The section demonstrates a gradual change of depositional environments from shallow-marine in the Lower Carboniferous to deep-water in the middle Carboniferous and Permian. The Tournaisian and Visean rocks (Tas-Ary Formation, not less than 950 m) were formed on the open shelf or ramp with predominant carbonate sedimentation. They were deposited above the storm-wave base during the early Tournaisian and at greater depth later. The Serpukhovian–Middle (?) Permian rocks (Bel’kov Formation, not less than 300 m) were accumulated on the deep-water subaqueous slope and, possibly, at its base. Black shales and turbidite sandstones compose a significant part of the Bel’kov Formation. Sandstones have a siliciclastic–carbonate composition in the upper Lower Carboniferous and are carbonate-free up the section. The boundary between Tas-Ary and Bel’kov formations corresponds to a change in the shelf-to-basin profile and depositional style. At this time (the beginning of the Serpukhovian), the subsidence rate increased, a pronounced slope was formed, and a new source of clastics appeared on land. This reorganization was probably related to the Northern Taimyr orogen rise. The lithological similarity of the Lower Carboniferous deposits of the Tas-Ary Peninsula and Southern Taimyr, the synchronous shift in sedimentation from carbonate to terrigenous rocks, and the same source of clastic material for the Upper Carboniferous–Permian sandstones in both regions indicate their belonging to the same sedimentary basin in the Late Palaeozoic. We believe that the western part of the New Siberian Islands represented a continental margin in Late Devonian, Carboniferous and Permian times, and that it was a continuation of the Verkhoyansk margin. The latter is possible, taking into account rotation of the New Siberian Islands block according to the two-pole rotational model of the Amerasian basin opening.

Eastern part of the Central Taimyr belt is composed of Precambrian rocks penetrated by granites of the Snezhnaya complex (845–825 million years) and later overlain by mid‐Neoproterozoic sin‐ postorogenic sedimentary deposits of the Stanovaya‐Kolosova Group. Two competing concepts on the Precambrian history of the belt are dis‐ cussed. The first suggests that by the middle of the Neoproterozoic amalgamation of various terrains formed the Cen‐ tral Taimyr microcontinent, which afterwards collided with Siberia in Vendian. 2) According to the second point of view, which is shared by the authors of this article, the belt was part of the Siberian craton from at least the Mesopro‐ terozoic, and there is no suture that would separate it from the South Taimyr belt. To our surprise, during the field work in the South‐Eastern part of the Central Taimyr belt near the proposed “Vendian sutura”, assumed by the first concept, we found a granite pluton (Pregradnaya massif) intruding clastic rocks of Stanovaya‐Kolosova Group. Such setting is quite uncommon for the belt and contradicted to publications, describing the mentioned clastic rocks to overlay the granites and contain their debris. Dating of the pluton confirmed the field observations – its SRIMP zircon age has proved to be 609±2 Ma, an unusually young for this region. The pluton is located in a wide deformation zone separating the Precambrian rocks (to the northwest) and the Paleozoic deposits (to the southeast). Two minor bodies of similar porphyritic granite were found in the same zone further to the southwest, and it seemed logical to assume that a chain of Vendian granites marks boundary deformation zone. However, their dating (843±6 и 840±5 Ma) showed that they belong to Snezhnaya complex. In this paper, we discuss two Neoproterozoic magmatic ‘flare‐ups’ in the Central Taimyr Belt, which are dated at 845–825 and 640–610 Ma. Both ‘flare‐ups’ are evidenced by K‐rich per‐ aluminous granite batholiths intruded the upper crust. It is most probable that each flare‐up was related to a collision event completing an independent cycle in the evolution of the active margin of the Siberian paleocontinent.

Eastern part of the Central Taimyr belt is composed of Precambrian rocks penetrated by granites of the Snezhnaya complex (845–825 million years) and later overlain by mid‐Neoproterozoic sin‐ postorogenic sedimentary deposits of the Stanovaya‐Kolosova Group. Two competing concepts on the Precambrian history of the belt are dis‐ cussed. The first suggests that by the middle of the Neoproterozoic amalgamation of various terrains formed the Cen‐ tral Taimyr microcontinent, which afterwards collided with Siberia in Vendian. 2) According to the second point of view, which is shared by the authors of this article, the belt was part of the Siberian craton from at least the Mesopro‐ terozoic, and there is no suture that would separate it from the South Taimyr belt. To our surprise, during the field work in the South‐Eastern part of the Central Taimyr belt near the proposed “Vendian sutura”, assumed by the first concept, we found a granite pluton (Pregradnaya massif) intruding clastic rocks of Stanovaya‐Kolosova Group. Such setting is quite uncommon for the belt and contradicted to publications, describing the mentioned clastic rocks to overlay the granites and contain their debris. Dating of the pluton confirmed the field observations – its SRIMP zircon age has proved to be 609±2 Ma, an unusually young for this region. The pluton is located in a wide deformation zone separating the Precambrian rocks (to the northwest) and the Paleozoic deposits (to the southeast). Two minor bodies of similar porphyritic granite were found in the same zone further to the southwest, and it seemed logical to assume that a chain of Vendian granites marks boundary deformation zone. However, their dating (843±6 и 840±5 Ma) showed that they belong to Snezhnaya complex. In this paper, we discuss two Neoproterozoic magmatic ‘flare‐ups’ in the Central Taimyr Belt, which are dated at 845–825 and 640–610 Ma. Both ‘flare‐ups’ are evidenced by K‐rich per‐ aluminous granite batholiths intruded the upper crust. It is most probable that each flare‐up was related to a collision event completing an independent cycle in the evolution of the active margin of the Siberian paleocontinent.

Модель геологического строения осадочного чехла моря Лаптевых, принятая в настоящее время большинством геологов, предполагает, что нижний сейсмический комплекс чехла начинается апт-альбскими отложениями. Последние могут быть изучены в естественных выходах на о. Котельный. В статье описан разрез Туор-Юряхской мульды, в котором вскрыта нижняя часть мелового комплекса. Разрез сложен континентальными угленосными породами мощностью около 100 м. Маркирующие пласты делят его на пять пачек, которые прослежены вдоль западного борта мульды на расстояние до трех километров. Спорово-пыльцевые комплексы и макроостатки растений указывают на то, что почти весь видимый разрез “среднего” мела имеет альбский возраст; к апту, возможно, относится только его нижняя часть мощностью не более 14 м. В 15 м выше подошвы мелового комплекса обнаружены морские фации, содержащие фораминиферы альба. Разрез меловых пород подстилается нижнеюрскими морскими глинами и алевритами. Ассоциации фораминифер из этой части разреза характерны для верхнего синемюра-основания плинсбаха, ископаемые двустворки указывают на позднесинемюрский возраст вмещающих пород. Перерыв в осадконакоплении длительностью около 70 млн лет никак не выражен в разрезе: фактически эту границу возможно обосновать только по микрофоссилиям. Такая неотчетливость контакта нижнеюрских и среднемеловых пород совершенно не соответствует геофизическим характеристикам подошвы нижнего сейсмокомплекса чехла восточной части моря Лаптевых. Последняя описывается как самый отчетливый сейсмический горизонт в разрезе чехла, причем предполагается несогласное залегание нижнего сейсмокомплекса на пенепленизированной поверхности литифицированных и дислоцированных пород. Такому описанию в гораздо большей степени отвечает подошва эоценовых отложений, которые наблюдались нами на островах Бельковский и Котельный. В статье обсуждается применимость полученных на суше результатов к интерпретации сейсмических разрезов шельфа моря Лаптевых. Сделан вывод, что неотчетливость границы между нижнеюрскими и среднемеловыми толщами в изученном разрезе может быть вызвана локальными причинами. Проведенные наблюдения не опровергают представления о вероятном апт-альбском возрасте пород в основании нижнего сейсмокомплекса, но предлагается все же сохранить в качестве одного из возможных рабочих вариантов распространенную ранее идею об эоценовом возрасте нижнего сейсмокомплекса осадочного чехла восточной части моря Лаптевых.

The model of geological structure of sedimentary cover of the Laptev Sea accepted by most geologists suggests that the lower seismic complex of the cover begins by the Aptian–Albian sedimentary rocks. They can be studied in natural outcrops of Kotelnyi Island. The section of the Tuor-Yuryakh Trough, which exposes the lower part of the Cretaceous complex, is described in the paper. It is composed of continental coaliferous rocks ~100 m thick. The marking beds divide it into five members, which are traced along the western wall of the trough at the distance up to 3 km. The spore–pollen complexes and plant megafossils indicate that almost the entire visible section of the mid-Cretaceous is Albian. Only its lower part no more than 14 m thick can probably belong to the Aptian. Marine facies with Albian foraminifers were found 15 m above the bottom of the Cretaceous complex. The section of the Cretaceous rocks is underlain by the Lower Jurassic marine clays and siltstones. The foraminifer assemblages of this part of the section are typical of the upper Sinemurian–Pliensbachian and fossil bivalves indicate late Sinemurian age of the host rocks. The hiatus ~70 Ma duration has no expression in the section and this boundary can de facto be substantiated only by microfossils. This vague contact between the Lower Jurassic and mid-Cretaceous rocks does not correspond to geophysical characteristics of the bottom of the lower seismic complex of the cover of the eastern part of the Laptev Sea. The latter is described as the most evident seismic horizon of the section of the cover, suggesting unconformable occurrence of the lower seismic complex on a peneplenized surface of lithified and dislocated rocks. This is mostly similar to the bottom of the Eocene sediments, which were observed on Belkovsky and Kotelnyi islands. The paper discusses possible application of our land results for interpretation of the shelf seismic sections of the Laptev Sea. It is concluded that local reasons are responsible for a vague boundary between the Lower Jurassic and mid-Cretaceous sequences in the section studied. Our observations support ideas on possible Aptian–Albian age of the rocks of the basement of the lower seismic complex; however, it is proposed to use also the previously popular idea on the Eocene age of the lower seismic complex of sedimentary cover of the eastern part of the Laptev Sea as one of the possible working scenarios.

U–Pb detrital zircon results from New Siberian Islands sandstones illuminate the long-lived controversy regarding the continuation of the Uralian orogen into the Arctic region. A dominant age peak of c . 285 Ma from Permian sandstone requires proximal derivation from Taimyr’s Carboniferous–Permian granites, thought to reflect syn- to post-tectonic Uralian magmatism. The provenance of Devonian sandstone has Baltica affinities. The data record a dramatic change in provenance between Devonian and Permian time, from Baltica to a mixed Baltica + Uralian source. Our results confirm that the Uralian foreland basin extended from Taimyr to the New Siberian Islands. Supplementary material: Sample co-ordinates, sediment petrography and heavy mineral analysis, U–Pb data tables and description of analytical methods associated with detrital zircon and granite analyses are available at http://www.geolsoc.org.uk/SUP18784.

Much of the material of Paleozoic successions of Kotelnyi Island (New Siberian Islands) is composed of various carbonates, which accumulated in relatively shallow conditions in the Ordovician–Middle Devonian. Such deposits are widespread in synchronous sections throughout the Eastern Arctic and therefore attract attention as a potential tool for interregional correlations. In paleotectonic reconstructions, Kotelnyi Island either is included in terrain which was disconnected from the Siberian Platform in the Paleozoic or is joined to it. These different interpretations result from lack of primary evidence. This paper presents new data on stratigraphy and macroand microfauna of the Upper Ordovician and Silurian of the central regions of Kotelnyi Island. For this interval, we propose a correlation of the studied sections with those of adjacent regions. A conclusion is drawn on the basis of the similarity of lithology and fossil assemblages and also shared trends in the evolution of the sedimentary environment that the Upper Ordovician–Silurian beds of Kotelnyi Island, Taimyr, and the Siberian Platform accumulated in a single shelf basin, which apparently also extends to northeastern Chukotka.

Архипелаг Новосибирские острова, расположенный в северо-восточной части континентального шельфа Евразии, рассматривают в составе экзотического террейна, столкнувшегося с Сибирью в начале мела. Остров Бельковский, на котором проведены исследования, максимально приближен к предполагаемой западной границе этого террейна. Именно на нем следовало ожидать присутствие признаков того, что в палеозое его территория располагалась на краю океанического бассейна. Разрез верхнего девона о. Бельковский сложен непрерывной последовательностью глубоководных терригенных отложений, которые продолжают тенденцию к углублению бассейна, выявленную ранее на сеседнем о. Котельный. В основании разреза на платформенных известняках среднего девона залегают маломощные доманиковые фации. Основная часть разреза, мощностью более 4 км, сложена отложениями гравитационых потоков, включающими турбидиты, глинистые и глыбовые диамиктиты и, в верхней части, олистостромы. Они накапливались на склоне бассейна или у его подножия. На многих уровнях эти отложения перемыты вдольсклоновыми придонными течениями. В кровле разреза залегают органогенные известняки, свидетельствующие о компенсации прогиба. Согласно определениям конодонтов, изученные глубоководные терригенные породы накапливались в интервале: нижний фран–нижний турне – во время позднедевонской эпохи рифтогенеза. Полученные данные позволяют реконструировать на шельфе моря Лаптевых рифтогенный прогиб северо-северо-западного простирания, сходный с другими рифтами восточной окраины Сибирской платформы.

Впервые для о. Котельный детально изучены остракоды из отложений среднего-верхнего ордовика: малодиринг-айанской, терютехской и анисинской свит. Даны краткие характеристики ордовикских местонахождений на рр. Туор-Юрях и Казарка, в которых обнаружены остатки остракод этого возраста. Приводится описание новых видов, которые относятся к родам Krausella, Longiscula. Для известных ранее видов остракод даны изображения.

The archipelago of New Siberian Islands situated on the northeastern continental shelf of Eurasia is considered a part of an exotic terrane that collided with Siberia in the Early Cretaceous. Bel’kov Island is located close to the inferred western boundary of this terrane and thus should demonstrate attributes of its localization at the margin of the Paleozoic oceanic basin. The Upper Devonian section on Bel’kov Island is a continuous sequence of deepwater terrigenous rocks, which indicates a tendency toward deepening of the basin previously revealed on adjacent Kotel’ny Island. The lowermost Upper Devonian unit on Bel’kov Island is represented by thin Domanik-like strata resting on the Middle Devonian carbonate platform. The main body of the Upper Devonian sequence, more than 4 km in total thickness, is made up of gravity-flow sediments including turbidites, clay and block diamictites, and olistostromes in the upper part of the section, which accumulated at the slope of the basin or its rise. At many levels, these sediments have been redeposited by along-slope currents. The uppermost unit of organogenic limestone is evidence for compensation of the trough. According to conodont assemblages, the deepwater terrigenous rocks were deposited from the early Frasnian to the early Tournaisian. This time is known for extensive rifting in the eastern Siberian Platform. The data obtained allowed us to reconstruct a NNW-trending Late Devonian rift basin on the Laptev Sea shelf similar to other rifts at the eastern margin of the Siberian Platform.