New Find of Cuticular Coal in the Franz Josef Land

Coal pebbles found in 1994 in the Greham Bell Island (Franz Josef Land Archipelago) are made up of the Barzas-type cuticular liptobiolith. The coal belongs to the initial stage of catagenesis and is characterized by high content of cutinite (up to 70%) with very low reflectance (R_o= 0.1%). Maceration products show some tegillate elements of Arthropodaand individual Devonian spores. It is supposed that plant cuticle and Arthropoda exocuticle are present in this coal. The obtained data suggest the presence of Paleozoic rocks in the sedimentary sequence, although they are not yet recovered. These data complement the available information on the distribution of specific Devonian coals and allow us to have a new insight into the zoogenic material involved in the coal formation.     

Radiocarbon dating the extinct caribou on Franz Josef Land

Seven old, shed caribou ( Rangifer tarandus ) antlers from Alexandra Land, in the high arctic Franz Josef Land archipelago where no caribou are found today, were dated to between 3870 ± 70 and 2245 ± 70 radiocarbon years BP. All were found on the ground above the highest shoreline, thus not transported there by sea-ice. That the ages all fall into a relatively narrow time-span suggests that they originate from a population of caribou that really lived on Alexandra Land. We suggest that they migrated there after the culmination of the Holocene climatic optimum ( c . 6000 to 4500 BP) when the climate again became colder and the sea-ice more persistent. The climate during that period can be compared with that of Nordaustlandet on Svalbard today, where a population of caribou still exists.     

Late Weichselian ice-sheet sensitivity over Franz Josef Land, Russian High Arctic, from numerical modelling experiments

A numerical ice-sheet model was run in order to produce reconstructions of the Late Weichselian ice coverage of Franz Josef Land, Russian High Arctic. The model grid covers the archipelago and surrounding shelf, but does not include the whole Barents-Kara region or the extensive ice cover that may have built up there. One experiment, where rates of iceberg calving at the grounded margin were curtailed because of the assumed presence of permanent thick sea ice, yielded a single I.8 km-thick ice dome which covered the entire archipelago and surrounding sea. If, however, iceberg calving were included in the model's environmental input, the extent of the ice sheet would be limited to the periphery of the archipelago. If a large ice sheet existed over Franz Josef Land, the deglaciation of the islands may have been linked to the decay of the adjacent Barents-Kara Sea Ice Sheet, permitting iceberg calving (enhanced by relative sea-level rise) to occur. The introduction of a water-depth-related iceberg calving function at 15 000 yr ago forced an initial rapid rate of ice-sheet decay of 30 000 km³ 1000 yr'. However, as the ice sheet thinned, and isostatic rebound began, the calculated rate of iceberg calving was reduced such that ice remained over the archipelago at 8000 yr ago. The model's failure to simulate complete ice-sheet decay by 8000 yr ago is at variance with radiocarbon-dated raised terraces on Franz Josef Land, which indicates the complete deglaciation of the islands at this time.     

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.     

Sr-Nd-Pb isotopic systems in basalts of the Franz Josef Land Archipelago

Rb, Sr, Sm, Nd, U, and Pb contents and Sr, Nd, and Pb isotopic composition were determined in tholeiite and subalkaline basalts (in both whole-rock samples and individual minerals) from the Franz Josef Land Archipelago. Isotopic data obtained for the Arctic basin are similar to those for islands from the Pacific, Atlantic, and Indian Oceans. The assimilation of crustal (sedimentary) rocks by primary depleted material makes isochron determination of basalt age difficult or impossible. The subalkaline basalts (basaltic andesites) were presumably formed by the metasomatic introduction of incompatible elements in tholeiitic basalts and, only partially, through crustal contamination and fractional crystallization.     

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...     

Current trends of ice coverage changes in the Franz Josef Land Archipelago area

Doklady Earth Sciences - The data on the ice distribution in the Franz Josef Land Archipelago area during the 2010/2011 and 2014/2015 ice seasons depending on climate oscillations are presented...     

Platinum-group minerals in dolerites from Alexandra Land Island: (Franz Josef Land Archipelago)

Lavas in Alexandra Land Island of the Franz Josef Land Archipelago bear Au-Cu-Pd-type mineralization. The found mineral species belong to the Cu-Au-Pd and Pd-Cu-(Te + Sb + S + As) systems being, respectively, (i) cuproauride (Au(Cu, Pd)) and auricupride (Au(Cu,Pd)₃) and (ii) phases similar to skaergaardite (PdCu), nielsenite (PdCu₃), and numerous S-Te-Sb-Pd-Cu phases of various compositions. The morphology of PGM existing as tiny grains and films along the boundaries of plagioclase and clinopyroxene and in cracks, their crystallization at low temperatures predicted by experimental data, and the presence of native copper with sulfur impurity are signatures of postmagmatic origin. The Alexandra Land tholeiitic basalts and dolerites were, most likely, produced by the hotspot which may be the source of PGE-bearing intrusions in eastern Greenland that contain PGM similar to those discussed in the paper.     

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...     

Geology and tectonics of the northeast Russian Arctic region,based on seismic data

The structure of the sedimentary cover and acoustic basement in the northeastern Russian Arctic region is analyzed. Beneath the western continuation of the North Chukchi trough and Vil’kitskii trough, a Late Caledonian (Ellesmere) folded and metamorphozed basement is discovered. It is supposed that Caledonides continue further into the Podvodnikov Basin until the Geofizikov branch. A large magnetic anomaly in the Central Arctic zone has been verified by seismostratigraphic data: the acoustic basement beneath the Mendeleev (and partially Alpha) Ridge is overlain by trapps. Wave field analysis showed that the acoustic basement of the Lomonosov Ridge has folded structure, whereas beneath the Mendeleev Ridge, the sporadic presence of a weakly folded stratum of Paleozoic platform deposits is interpreted. It is supposed that the Caledonian and Late Cimmerian fold belts in the periphery of the Arctida paleocontinent appeared as a result of collision between arctic continental masses and southern ones. After Miocene extension and block displacements identified from appearance of horsts, grabens, and transverse rises both on the shelf and in the ocean, a general subsidence took place and the present-day shelf, slope, and the deepwater part of the Arctic Ocean formed.     

New data on the geological structure of the southwestern Mendeleev Rise,Arctic Ocean

This communication considers the ideas about the geological structure of the southwestern Mendeleev Rise belonging to the East Arctic rises of the Arctic Ocean. These ideas have resulted from analyzing the data obtained from bathymetric surveys, visual observations, and bottom coring using the technical tools of a research submarine. We distinguished the lower sequence of quartzite sandstones and dolomites, which has a visible thickness of about 230 m and occurs in the lowermost visible section, at depths between 1500 and 1270 m. This sequence is superimposed with stratigraphic and angular unconformity by the upper sequence of limestones and sandstones having a visible thickness of 40 m. The lower sequence is pierced by subvolcanic rocks of basaltic to andesitic composition, and in the lowermost part of the slope, a tuffaceous sequence having a visible thickness of 50 m adjoins it.     

Redating the advance of the New Zealand Franz Josef Glacier during the Last Termination: evidence for asynchronous climate change

Dating climatic and environmental records with accuracy and precision is critical if we are to robustly test hypotheses of synchronous change between the hemispheres. In the southern hemisphere, the advance of the New Zealand Franz Josef Glacier to the Waiho Loop terminal moraine has been used as evidence of synchronous global change during the Younger Dryas Chronozone. However, radiocarbon ages for wood incorporated into the sediments associated with the advance span an interval of 900 years. Here we demonstrate that weathered ‘old’ wood was incorporated into the deposit prior to, or during, the advance, and that this material is highly susceptible to contamination by young carbon, resulting in the wide range of age estimates reported previously. We have identified material with little evidence of reworking (well-preserved wood with bark attached) that provides a statistically robust mean radiocarbon age of 11,062±30 BP (13.1 ka) for the advance of the Franz Josef Glacier. The timing of this event falls within the later part of the Antarctic Cold Reversal. Comparison with local, regional and global records suggests that cold conditions in the Southern Ocean were probably experienced in New Zealand at this time, driving the glacial advance.     

New data on change in ice thickness in the Arctic Ocean

Doklady Earth Sciences -     

New seismicity map for the European sector of the Russian Arctic region

Based on seismological monitoring data specifying earthquake epicenters, a new map is made for the Western sector of the Russian Arctic region. The seismicity data is reworked in detail by specifying the epicentral positions of earthquakes and adding data on weak seismicity for areas which were earlier insufficiently studied, including those at the boundary of the Arctic Shelf of the Russian Federation. The fundamental possibility of applying seismological observations to construct a regional geodynamic map is discussed (in particular, the important role of island-based seismic stations). The possibility of specifying the nature of seismicity in terms of spectral-temporal analysis (STAN) of waveforms based on data from the new seismic station on the Franz Josef Land is considered. Possible application of the character of seismicity obtained from geophysical data to specify the geodynamic nature of events accompanying interaction of the ridge and shelf spreading is discussed.     

雄安新区航磁推断的三维基底构造特征

雄安新区地处平原厚覆盖区,前新生界岩性基底结构与构造是城市规划与开发的重要依据.本文依据1988年在雄安新区及周边开展航空磁测及伽马能谱测量成果,重新整理了岩矿石物性、磁场及推断岩性构造图等资料,分析了基底构造及油气分布区特征,给出了三维岩性构造图.分析认为该地区的区域地壳深部结构相对稳定.     

New data on the present-day active fluid regime of fractured zones of crystalline basement and sedimentary cover in the eastern part of Volga-Ural region

The study area is the South Tatarstan Arch located in the Volgo-Ural Region, which is an enigmatic crustal segment occupying one third of the East European Platform. Monitoring studies have shown that fluid discharge processes are still active and time-dependent. This paper presents an integrated review of the geological, geophysical, hydrochemical and geochemical studies of the crystalline basement of Tatarstan. These studies are based on the stratigraphic and compositional schemes within the crystalline basement, the drilling of deep wells, the geodynamic activity of the fractured zones of the crystalline basement and the presence of fluids therein. Furthermore, the changes in the chemical composition of the basement waters are taken into account.     

Tectonics of the eastern Arctic region

The Vendian (Baikalian), Late Devonian (Ellesmerian), and Mid-Cretaceous (Brookian) orogenies were three cardinal events in the history of formation and transformation of the continental crust in the eastern Arctic region. The epi-Baikalian Hyperborean Craton was formed by the end of the Vendian (660–550 Ma), when the Archean-Proterozoic Hyperborean continental block was built up by the Baikalian orogenic belt and concomitant collision granitoids. As judged from the localization of deepwater facies, the Early Paleozoic ocean occupied the western part of the Canadian Arctic Archipelago, western Alaska, and the southern framework of the Canada and Podvodnikov basins and was connected with the Iapetus ocean. The closure of the Early Paleozoic Arctic basins is recorded in two surfaces of structural unconformities corresponding to the pre-Middle Devonian Scandian orogenic phase and the Late Devonian Ellesmerian Orogeny; each tectonic phase was accompanied by dislocations and metamorphism. The Ellesmerian collision was crucial in the Caledonian tectogenesis. The widespread Late Devonian-Mississippian rifting probably was a reflection of postorogenic relaxation. As a result, the vast epi-Caledonian continental plate named Euramerica, or Laurussia, was formed at the Devonian-Carboniferous boundary. The East Arctic segment of this plate is considered in this paper. In the Devonian, the Angayucham ocean, which was connected with the Paleoasian and Uralian oceans [62], separated this plate from the Siberian continent. The South Anyui Basin most likely was a part of this Paleozoic oceanic space. The shelf sedimentation on the epi-Caledonian plate in the Carboniferous and Permian was followed by subsidence and initial rifting in the Triassic and Jurassic, which further gave way to the late Neocomian-early Albian spreading in the Canada Basin that detached the Chukchi Peninsula-Alaska microplate from the continental plate [25]. The collision of this microplate with the Siberian continent led to the closure of the South Anyui-Angayucham ocean and the development of the Mid-Cretaceous New Siberian-Chukchi-Brooks Orogenic System that comprised the back Chukchi Zone as a hinterland and the frontal New Siberian-Wrangel-Herald-Lisburne-Brooks Thrust Zone as a foreland; the basins coeval with thrusting adjoined the foreland. Collision started in the Late Jurassic; however, the peak of the orogenic stage fell on the interval 125–112 Ma, when ophiolites had been obducted on the margin of the Chukchi Peninsula-Alaska microplate along with folding and thrusting accompanied by an increase in the crust’s thickness, amphibolite-facies metamorphism, and growth of granite-gneiss domes. The magmatic diapir of the De Long Arch that grew within the continental plate in the Mid-Cretaceous reflected a global pulse of the lower mantle upwelling that coincided with the maximum opening of the Canada Basin. The present-day appearance of the eastern Arctic region arose in the Late Mesozoic and Cenozoic owing to the opening of the Amerasia and Eurasia oceans. Sedimentary basins of various ages and origins—including the Late Devonian-Early Carboniferous grabens, the spatially coinciding Late Jurassic-Early Cretaceous rifts related to the opening of the Canada Basin, the syncollision basins in front of the growing orogen, and the Cretaceous-Cenozoic basins coeval with strike-slip faulting and rifting at the final stages of orogenic compression and during the opening of the Eurasia ocean were telescoped on sea shelves.