The structural features of the continental shelf and oceanic basin of the Eastern Arctic as well as its tectonic history are particularly controversial. The New Siberian Islands (NSI) archipelago is one of the few territories accessible for direct geologic study in this region. The De Long Islands occupy the northernmost part of the NSI archipelago and are situated at the junction of the major tectonic units of the Eastern Arctic. This, coupled with the lack of geologic information caused by the remoteness of the islands, leads to many debates concerning the tectonic affinity and relations of the De Long Islands with adjacent units. Here we review the geology and paleomagnetism for Cambrian-Ordovician rocks of the De Long Islands. The similarity of benthic fauna groups of the De Long and adjacent Anjou basins to the Siberian Taimyr-Verkhoyansk margin indicates that the De Long unit was close to Siberia. However, some detrital zircon groups indicate their non-Siberia provenances. In this review, based on paleomagnetic evidence, we propose a global tectonic reconstruction showing interactions and drift kinematics of the NSI and the nearby Arctic terranes as well as the cratons Siberia, Laurentia and Baltica from 510 to 450 Ma. We propose the existence of a New Siberian - Chukotka - Alaska carbonate platform - a large epicontinental basin between Siberia and Laurentia with a biogeographic connection to the Verkhoyansk shelf of Siberia and potential detrital provenances from Chukotka - Alaska. The mostly transform tectonic boundaries surrounding the platform enabled its constituent terranes to drift independently while preserving conditions for unimpeded migration of Siberian benthic fauna but not for Siberia-derived zircons. Moreover, its De Long margin developed up to the Ordovician period in a suprasubductional setting and perhaps had a tectonic connection with the Mendeleev Rise.

This work presents finalized results of our paleomagnetic study of Paleozoic rocks of Henrietta, Jeannette and Bennett islands and their implications for tectonic reconstructions. We discuss possible relationships of the Cambrian section of the De Long sedimentary basin with the Verkhoyansk margin of Siberia, the terranes of the Kolyma-Omolon group, the Chukotka-Alaska microcontinent, as well as with the structures of the submerged Mendeleev Ridge. We propose a new tectonic model, in which the De Long structures feature as the frontalmost part of a large transform system that existed on the periphery of the Siberian paleocontinent.

Архипелаг Новосибирские о-ва - один из немногих объектов, доступных для прямых геологических наблюдений на шельфе Восточной Арктики. Существует несколько моделей, по-разному трактующих палеозойскую тектоническую историю и структурную принадлежность Новосибирского террейна. Одни предполагают прямую связь с пассивной окраиной Сибирского палеоконтинента, другие - с окраинно-континентальными бассейнами Балтики, Лаврентии либо Чукотско-Аляскинской микроплиты. Проведённые нами палеомагнитные исследования позволили разработать траекторию кажущегося движения полюса для раннепалеозойского интервала геологической истории, на основании которой можно заключить, что Новосибирский террейн не мог являться частью названных континентальных плит. Рассмотрены возможные тектонические сценарии его палеозойской истории, построены и обсуждаются соответствующие глобальные реконструкции, раскрывающие палеогеографию и вероятную взаимную кинематику дрейфа террейнов Восточной Арктики.

The paper presents results of geochronological and paleomagnetic studies of the volcanogenicsedimentary sequence of Henrietta Island in the East Siberian Sea. Our 40Ar/39Ar investigations confirm existing ideas that the bottom part of the section formed in the Ediacaran (~565 Ma) and that the basalts in the top of the section formed before the middle Cambrian (~520 Ma). Calculated paleomagnetic data confirm that during the rocks formation the territory of present-day Henrietta Island was located close to the 20° latitude, which lets us adjust some information published earlier on the age and natural remanent magnetization of the dolerite dikes of the nearby Jeannette Island. The new data also let us propose that a regional tectonothermal event, probably caused by accretion-related processes, took place at the beginning of the Ordovician.

The New Siberian Islands archipelago is one of the few research objects accessible for direct study on the eastern Arctic shelf. There are several models that have different interpretations of the Paleozoic tectonic history and the structural affinity of the New Siberian Islands terrane. Some infer a direct relationship with the passive continental margin of the Siberian paleocontinent. Others connect it with the marginal basins of Baltica and Laurentia, or the Chukotka-Alaska microplate. Our paleomagnetic investigation led us to create an apparent polar wander path for the early Paleozoic interval of geological history. Based on it we can conclude that the New Siberian Islands terrane could not have been a part of these continental plates. This study considers the possible tectonic scenarios of the Paleozoic history of the Earth, presents and discusses the corresponding global reconstructions describing the paleogeography and probable mutual kinematics of the terranes of the Eastern Arctic.

New characteristics and generalized geostructural, isotope-geochronological, and paleomagnetic data are presented for the first time for the territory of Jeannette Island in the De Long Archipelago. Until recently, this small rock outcrop in the East Siberian Sea, discovered in the late 19th century, has been in effect a blank spot on the geological map. Field work made in 2013 and subsequent laboratory analysis of the obtained sample collection show that the island has a volcanogenic-sedimentary section including many thin (up to several meters) dolerite dikes. These dikes are the main target of the study. Newly obtained 40Ar/39Ar isotope-geochronological data indicate that the earliest dike intrusion stage corresponds to the Ediacaran (553.6 ± 10.3 Ma). Several subsequent tectonothermal events can be inferred until and through the Early Carboniferous, which affected the stability of the isotope system in the dolerites. In addition, paleomagnetic data confirm at least one more stage of dike emplacement, in the Early Ordovician, as the coordinates of the virtual geomagnetic poles for the dikes are nearly identical to those of the Ordovician paleomagnetic pole determined for carbonate rocks of Kotelny Island. The study describes the main petromagnetic characteristics and magnetic mineralogy of the studied dolerites, validating the primary thermoremanent nature of the identified characteristic component. The results agree with available information on the paleomagnetism, tectonics, and paleogeography of the New Siberian Islands.