Geodynamics of the Barents–Kara margin in the Mesozoic inferred from paleomagnetic data on rocks from the Franz Josef Land Archipelago

New data on paleomagnetism and isotope geochronology of Jurassic and Early Cretaceous basic igneous rocks on Franz Josef Land Archipelago (FJL) represented by flows and dikes are discussed. The first paleomagnetic data obtained for these rocks offer the opportunity to suggest a model of spatial changes in the FJL block position during the Jurassic?Cretaceous. In the Early Jurassic, the block occupied a different position relative to Europe from the modern one. It was displaced in the northeasterly direction by a distance of approximately 500 km and rotated clockwise by about 40° relative to its modern position. By the Early Cretaceous, the FJL block occupied a position close to the present-day one avoiding subsequent substantial relative displacements. The data obtained are of principal significance for reconstructing the geodynamic evolution of Arctic structures in the Mesozoic and contribute greatly to the base of paleomagnetic data for the Arctic region, development of which is now in progress.     

Could the Norilsk Region Dolerite Sills Have Recorded Geomagnetic Field Reversals? Results of Mathematical Modeling

Izvestiya, Physics of the Solid Earth - The possibility of reconstructing geologic events by identifying patterns in variations of the geomagnetic field related to reversals is one of the...     

Formation Peculiarities of the Franz Josef Land Volcanic Province,Arctic Ocean: The Melt Movement Direction Estimated from Anisotropy of Magnetic Susceptibility

Doklady Earth Sciences - The work presents the first results on the anisotropy of magnetic susceptibility in Hooker Island basaltoids; this anisotropy is related to the direction of motion of the...     

Paleomagnetism of trap basalts in the northwestern Siberian craton,from core data

We present new paleomagnetic data for continental flood basalts (Siberian traps) obtained from cores of two boreholes in the northwestern Noril'sk area, within the Kharaelakh and Vologochan basins. Paleomagnetic measurements of lava and tuff samples from KhS-59 and SSV-19 boreholes allowed reconstructing and correlating the polarity patterns. Thus multiple paleomagnetic anomalies (PMA) have been discovered as brief polarity changes in narrow intervals of the magnetostratigraphic section above the principle reversal at the boundary between the Ivakin and Syverma Formations.The most prominent anomalies are observed at the bases of the Morongo and Mokulai Formations. The samples from the anomalous intervals differ from those of other intervals neither in rock magnetic properties, nor in mineralogy and magnetic grain sizes. Therefore, the revealed PMA record excursions of the geomagnetic field. Comparison of the results with the Meishan Global Stratotype Section and Point (GSSP) of the Permian–Triassic boundary implies a revision to the P–T position in the trap basalt succession of the Noril'sk area. Judging by the EMF behavior, basalts in this part of the trap province erupted for at least 500 kyr during an interval of stable normal polarity.     

Geology and paleomagnetism of the Vendian and lower Cambrian deposits from Argun terrane (Eastern Transbaikalia)

We present new data on the geologic structure and paleomagnetism of the Vendian and Lower Cambrian deposits of the Argun River region in East Transbaikalia. We discuss the issues related to the recognition of the Argun microcontinent within the composite blocks of the south-eastern part of the Central Asian belt, which are traditionally combined in the Amuria superterrane. Our paleomagnetic determinations help us justify the equatorial position of the sedimentary basin, in which the deposits of the Argun terrane Beletuy and Bystrin formations formed 560 and 525 Ma, close to or directly on the margin of the Siberian paleocontinent. This data is essential for the reconstruction of the geodynamic evolution of Siberia and Central Asia at the Precambrian-Paleozoic boundary.     

Paleomagnetism of traps of the Franz Josef Land Archipelago

The paper presents results of paleomagnetic studies of traps of the Franz Josef Land (FJL) Archipelago. This area is considered to be part of the Barents Sea Large Igneous Province (LIP) and is usually associated with the Early Cretaceous stage of plume activity, by analogy with other manifestations of late Mesozoic trap magmatism in the High Arctic. Recent isotope-geochemical studies, however, suggest a much longer history of basaltoid magmatism in the FJL area, from Early Jurassic through Early Cretaceous, with three pulses at 190, 155, and ≈ 125 Ma. Given a significant difference in age, paleomagnetic directions and corresponding virtual geomagnetic poles are supposed to form discrete groups near the Jurassic-Early Cretaceous paleomagnetic poles of Eastern Europe. However, the calculated virtual geomagnetic poles, on the contrary, show a single “cloud” distribution, with its center being shifted to the Early Cretaceous paleomagnetic poles of Siberia. The performed analysis demonstrates that the significant variance is caused mostly by the high-latitude position of the FJL and secular variations of the geomagnetic field during the formation of the traps. Products of the Early Cretaceous magmatism evidently prevail in the data sample. The coincidence of the average paleomagnetic pole of the FJL traps with the Early Cretaceous (145-125 Ma) interval of the apparent polar wander path of Siberia rather than Eastern Europe confirms the hypothesis of the Mesozoic strike-slip activity within the Eurasian continent. This activity might be a natural result of the evolution of the Arctic Ocean.     

Paleomagnetic Evidence for the Iceland Plume Paleogeographic Stationarity and Early Cretaceous Manifestation in the High Arctic

Doklady Earth Sciences - Here we present reconstructions indicating the stationary position and paleogeography of the Iceland plume, as well as its direct connection to the Mesozoic–Cenozoic...     

Early Cretaceous Basalts of the Franz Josef Land Archipelago: Correspondence of New 40Ar/39Ar and Paleomagnetic Data

Doklady Earth Sciences - The paper presents new 40Ar/39Ar age determination of basalts from the Franz Josef Land archipelago. The obtained set of dates confirms the predominance of products only of...