D.V. Metelkin

The oldest island arc complex of Taimyr: Concerning the issue of the Central-Taimyr accretionary belt formation and paleogeodynamic reconstructions in the arctic

In this paper we provide data on the oldest island arc complex of Taimyr, which was established within the Central-Taimyr accretionary belt. We demonstrate its relationship with the mainly turbiditic back-arc basin complex. U-Pb isotopic data for zircons are presented from a plagiogranite and a plagiorhyodacite, indicating that the island arc formed 961–969 m.y. ago from a substance with a Mezoproterozoic model age: TNd(DM) varies from 1170 to 1219 Ma. Paleomagnetic investigations performed on the island arc complex rocks showed that the paleomagnetic pole of the island arc is close to synchronous poles, obtained for the south-east of the Siberian craton. Consequently, the island arc whose relicts are preserved in the modern structure of the Three Sisters Lake region was located in close proximity to the Taimyr margin of Siberia at the moment of its formation and could be separated from the continent by a back-arc basin. The data obtained have a fundamental significance for geodynamic paleoreconstructions in the Arctic sector for the Neoproterozoic.

The Mesozoic Apparent Polar Wander Path for the Siberian Domain of the Eurasian Plate

Comparison of the apparent polar wander paths (APWP) is one of the most important tasks in recent paleomagnetic study. The reliability of such trajectories is largely determined by the quality and quantity of paleomagnetic data used for their construction and uniformity of distribution of these data along the APWP. Approximately 400 paleomagnetic determinations largely characterizing the Paleozoic are now available for East Siberia. The basic features of the present-day structure of northern Eurasia were formed by the end of the Paleozoic. This fact served as a basis for construction of the so-called synthetic APWP for the Eurasian continent, according to which the latter is considered as a single rigid block in the Mesozoic‐Cenozoic [1, 2]. Though paradoxical, Mesozoic strata of Siberia, except for the Lower Triassic, are insufficiently studied by the paleomagnetic method. The paleomagnetic study of Mesozoic rocks in Siberia were largely aimed at solution of stratigraphic problems, which do not need high accuracy in determination of paleomagnetic poles. Despite their reliability, such data are unsuitable for solution of tectonic tasks. The main weakness of available determinations is related to the lack of paleomagnetic tests and wide age ranges (sometimes >50 (!) Ma) obtained for paleomagnetic poles. Therefore, paleomagnetic data on Europe and China [1, 2] were used to calculate the latitudinal position and spatial orientation of the Siberian tectonic domain of the Eurasian Plate in the Mesozoic‐Early Cenozoic. At the same time, the analysis of the geological structure and paleomagnetic data available for Siberia, East Europe, and Central Asia indicates that such constructions are inconsistent

The first data on the geology of Jeannette Island (De Long Archipelago, New Siberian Islands)

This paper presents the first actual information on the geology of Jeannette Island, one of the islands of the De Long archipelago located in the East Siberian Sea. We show that Jeannette Island has a volcano-sedimentary section dominated by volcaniclastic turbidites. The sequence identified on the southwestern coast of the island has a submonoclinal plunge complicated by secondary deformation structures, which indicate a general E-W direction of tectonic transport (in present-day coordinates). The sequence is intensely cut by multiple thin (up to a few meters) gabbro-dolerite dikes that are deformed conformably with the host rocks. The general geological framework of the island bears a close resemblance to that of nearby Henrietta Island located some 70 km to the east, which consists of a volcano-sedimentary cover of Early Paleozoic age. No organic remains have been found in the studied section of Jeannette Island. The preliminary results of isotope geochronological and paleomagnetic studies confirm the Late Precambrian-Early Paleozoic age assigned to the entire rock complex of Jeannette Island. The measured paleomagnetic directions are generally consistent with the directions of Lower Paleozoic rocks of Bennett Island (De Long archipelago) and Kotelny Island (Anzhu archipelago), which confirms our earlier conclusion that the New Siberian Islands shared a common tectonic history and that this structural element of the Arctic shelf appears to have been a terrane during the Early Paleozoic. This new information can help elucidate the possible relations between the marginal-continental, shelf, island and deep-seated structures of the Eastern Arctic.

Rotation parameters of the Siberian domain and its eastern surrounding structures during different geological epochs

The motion of lithospheric blocks was analyzed in the junction zone between the Eurasian Plate and its surrounding structures. Its present-day stage was considered using GPS and seismologic data. Models of the movement of a rigid plate are considered for Eurasia. A model of Eurasia (northern part of Asia) was used to determine the rotation parameters of its southern periphery (Amur Plate) based on GPS data for the Far East (Sikhote Alin profile), and Transbaikal regions are shown as an example. A model of the Amur Plate was used to illustrate the behavior of the extension zone on its western boundary represented by the Lake Baikal depression during the Kultuk earthquake (M = 6.3, August, 27, 2008). Paleomagnetic data made it possible to determine the rotation pole of the Siberian Craton relative to its surrounding folded structures during the Mesozoic and to estimate its kinematic parameters. The permanent position of the rotation pole in the relative coordinate system since the terminal Paleozoic until the Recent indicates a constant rotation velocity of the Siberian domain within the Eurasian Plate structure.

The first paleomagnetic data on dolerites from Jeannette Island (New Siberian Islands, Arctic)

The first paleomagnetic data on dolerite dikes from the volcanogenic–sedimentary section of Jeannette Island (De Long Archipelago, New Siberian Islands) are discussed. The petromagnetic data and results of the baked contact and fold tests are used to substantiate the nature of the characteristic magnetization component, which in combination with the 40Ar/39Ar dates implies its likely Late Precambrian–Early Paleozoic age. The calculated paleomagnetic pole makes it possible to extend the trajectory of the apparent polar movement for the New Siberian Islands block and confirms the assumption that this structural element of the Arctic shelf evolved as a terrane. Two variants of paleotectonic interpretation of the obtained data and their consistency with the available data on the geology and tectonics of the New Siberian Islands are considered.

Paleomagnetism of the Upper Paleozoic of the Novaya Zemlya Archipelago

The rock magnetic and paleomagnetic results from the Upper Paleozoic sedimentary sequences composing the isles of the Novaya Zemlya Archipelago are presented. The recorded temperature dependences of the magnetic susceptibility, the magnetic hysteresis parameters, and the results of the first-order reversal curve (FORC) measurements suggest the presence of single-domain or pseudo-single-domain magnetite and hematite grains in the rocks. The Upper Paleozoic deposits overall are promising for unraveling the tectonic evolution of the Barents–Kara region. Together with the rock magnetic data, the positive fold and reversal tests testify to the primary origin of the indentified magnetization components. However, the interpretation of the paleomagnetic data should take into account the probable inclination shallowing. New substantiation is offered for the paleomagnetic poles for Early Devonian and Late Permian. For the first time, paleomagnetic constraints are obtained for the Late Carboniferous boundary. It is shown that the Early Cimmerian deformation stage within the Paikhoi–Novaya Zemlya region is associated with the sinistral strike slip displacement along the Baidaratskii suture during which the internal structure of the Southern Novaya Zemlya segment could undergo shear in addition to the nappe-thrust transformations. The Northern Novaya Zemlya segment, which is shifted northwest with respect to the Southern segment, was deformed in the thrusting mode with an overall clockwise rotation of this segment relative to the East European Craton.

Causes of Cretaceous Remagnetization on the Southwestern Periphery of the Archipelago of the New Siberian Islands

This study demonstrates rock-magnetic and paleomagnetic investigations of Devonian and Mesozoic deposits of Kotelny, Stolbovoy, and Great Lyakhovsky islands. The results indicate that local remagnetization took place on the southwestern periphery on the archipelago of the New Siberian Islands. A comparison of new data with the apparent polar wander path for Siberia shows that the remagnetization happened during collisional events between 140 and 80 Ma and affected only the marginal part of the terrane of the New Siberian Islands that was directly facing the deformation front. The consistent younging of the remagnetization age from the south to the north indicates dextral rotation of the terrane of the New Siberian Islands during its collision with Siberia.

The Vendian Vorogovka Group of Yenisei Ridge: Chemostratigraphy and results of U–Pb dating of detrital zircons

Application of the method of isotope stratigraphy showed that the 87Sr/86Sr ratio in the least altered carbonate rocks of the Severnaya Rechka and Sukhaya Rechka formations in the Vorogovka Group of Yenisei Ridge ranges from 0.70813 to 0.70828, and δ13C varies from –0.7 to +1.8‰. Comparison of these data with similar data for the Late Precambrian sequences from other regions provides evidence for the Vendian age of the Vorogovka Group. This is supported by the results of LA ICP-MS U–Pb dating of detrital zircons from sandstone of the Severnaya Rechka Formation, which is the basal level of the group: the mid-weight age of the youngest zircon population is 584 ± 3 Ma.