Dorr N.,University of Bremen |
Lisker F.,University of Bremen |
Clift P.D.,University of Aberdeen |
Carter A.,Birkbeck, University of London |
And 3 more authors.
Tectonophysics | Year: 2012
The late Mesozoic-Cenozoic was a time of profound tectonic activity in the Arctic, with incipient spreading in the Arctic Ocean, Baffin Bay-Labrador Sea and North Atlantic, as well as the northward movement of the Greenland microplate leading to collision and deformation in Greenland, Arctic Canada and Svalbard (Eurekan Orogeny). It is, however, still unclear, how northern Svalbard, situated at the northwestern edge of the Barents Shelf, was affected by these processes. Furthermore, northern Svalbard has been proposed to have been a Cretaceous-Cenozoic sediment source to surrounding regions because it lacks a post-Devonian sedimentary cover. When erosion took place and how that related to the tectonic history of the Arctic, is yet unresolved. In order to reconstruct the erosion history of northern Svalbard, we constrained its thermal evolution using apatite fission track (AFT) thermochronology. Our data reveal AFT ages between 62±5 and 214±10. Ma, recording late Mesozoic-early Paleogene exhumation. Our data show that northern Svalbard was emergent and experienced erosion from the Early Jurassic and presumably through the Cenozoic, although total exhumation was restricted to ~. 6. km. Pronounced exhumation took place during Jurassic-Cretaceous time, probably linked to the extensional tectonics during the opening of the Amerasian Basin (Arctic Ocean). In contrast, Cenozoic ocean basin formation and the Eurekan deformation did not cause significant erosion of northern Svalbard. Nonetheless, AFT data show that Late Cretaceous-Early Paleocene fault-related exhumation affected some parts of northern Svalbard. Fault zones were reactivated due to the reorganization of Arctic landmasses during an early phase of the Eurekan deformation, which implies that this episode commenced ~. 20. m.y. earlier in Svalbard than previously understood. © 2011 Elsevier B.V.
Lebedeva-Ivanova N.N.,Uppsala University |
Lebedeva-Ivanova N.N.,Woods Hole Oceanographic Institution |
Gee D.G.,Uppsala University |
Sergeyev M.B.,Polar Marine Geological Research Expedition
Geological Society Memoir | Year: 2011
The c. 1500 km-long refraction and shallow reflection seismic profile, TransArctic 1989-1991 from the East Siberian shelf northwards across the Podvodnikov and Makarov basins, provides a four-layer model of the crust: layer I (V p = 1.7-3.8 km s -1) of sedimentary formations of late Mesozoic and Cenozoic age; layer II (V p = 5.0-5.4 km s -1) of older sedimentary rocks on the shelf and possibly also mafic volcanics in the basins; layer III (V p = 5.9-6.5 km s -1); and layer IV (V p = 6.7-7.3 km s -1) of crystalline crust. The East Siberian margin has c. 40 km thick continental crust, mainly composed of layers III and IV, both c. 15 km thick. Beneath the Podvodnikov Basin, the Moho depth varies from c. 20 km bsl at southern and northern ends to c. 30 km bsl at the centre beneath the Arlis Gap; it was probably formed by longitudinal extension of continental crust during the late Mesozoic. The edge of the Alpha-Mendeleev Ridge, separating the Podvodnikov and Makarov basins, has a crustal thickness of c. 25 km, mainly composed of layers III and IV. The deep Makarov Basin is probably composed of oceanic crust, 8-12 km thick, but includes spurs of continental crust, rifted off the Lomonosov Ridge. © 2011 The Geological Society of London.
Ekaykin A.,Saint Petersburg State University |
Eberlein L.,TU Dresden |
Lipenkov V.,Arctic and Antarctic Research Institute |
Popov S.,Polar Marine Geological Research Expedition |
And 3 more authors.
Cryosphere | Year: 2016
We present the results of glaciological investigations in the megadune area located 30 km to the east of Vostok Station (central East Antarctica) implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013-2015). Snow accumulation rate and isotope content (δD, δ18O and δ17O) were measured along the 2 km profile across the megadune ridge accompanied by precise GPS altitude measurements and ground penetrating radar (GPR) survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by 1 order of magnitude within the distance < 1 km, with the reduced accumulation at the leeward slope of the dune and increased accumulation in the hollow between the dunes. At the same time, the accumulation rate averaged over the length of a dune wave (22mmw.e.) corresponds well with the value obtained at Vostok Station, which suggests no additional wind-driven snow sublimation in the megadunes compared to the surrounding plateau. The snow isotopic composition is in negative correlation with the snow accumulation. Analysing dxs/δD and 17O-excess/δD slopes (where dxs =δD-8· δ18O and 17O-excessDln(δ17O/1000 + 1)-0.528 · In(δ18O/1000+1)), we conclude that the spatial variability of the snow isotopic composition in the megadune area could be explained by post-depositional snow modifications. Using the GPR data, we estimated the apparent dune drift velocity (4.6 ± 1.1myr-1). The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, a core drilled in the megadune area would exhibit the non-climatic 410-year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the megadune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the megadune areas. © 2016 Author(s).
Krajewski K.P.,Instytut Nauk Geologicznych PAN |
Gonzhurov N.A.,Polar Marine Geological Research Expedition |
Laiba A.A.,Polar Marine Geological Research Expedition |
Andrzej T.,Biologii Antarktyki PAN
Polish Polar Research | Year: 2010
The Panorama Point Beds represent a subfacies of the Early to Middle Permian Radok Conglomerate, which is the oldest known sedimentary unit in the Prince Charles Mountains, MacRobertson Land, East Antarctica. This unit records clastic sedimentation in fresh-water depositional system during the early stages of development of the Lambert Graben, a major structural valley surrounded by crystalline highlands in the southern part of Gondwana. It contains common siderite precipitated through early diagenetic processes in the swamp, stagnant water, and stream-flow environments. There are two types of siderite in the Panorama Point Beds: (1) disseminated cement that occurs throughout the sedimentary succession; and (2) concretions that occur at recurrent horizons in fine-grained sediments. The cement is composed of Fe-depleted siderite (less than 90 mol % FeCO3) with an elevated content of magnesium, and trace and rare earth elements. It has negative δ 13CVPDB values (-4.5 to-1.5‰).The concretions are dominated by Fe-rich siderite(morethan 90 mol % FeCO3), with positive δ 13CVPDB values (+1 to +8‰). There are no noticeable differences in the oxygen (δ18OVPDB between-20 and -15‰) and strontium (87Sr/86Sr between 0.7271 and 0.7281) isotopic compositions between the siderite types. The cement and concretions developed in the nearsurface to subsurface environment dominated by suboxic and anoxic methanic degradation of organic matter, respectively. The common presence of siderite in the Panorama Point Beds suggests that fresh-water environments of the Lambert Graben were covered by vegetation, starting from the early history of its development in the Early Permian.
Rusakov V.Y.,RAS Vernadsky Institute of Geochemistry and Analytical Chemistry |
Kuzmina T.G.,RAS Vernadsky Institute of Geochemistry and Analytical Chemistry |
Roshchina I.A.,RAS Vernadsky Institute of Geochemistry and Analytical Chemistry |
Shilov V.V.,Polar Marine Geological Research Expedition
Geochemistry International | Year: 2012
This paper is dedicated to the geochemical studies of two bottom sediment cores that were taken during Cruise 28 of the R/V Professor Logachev in the Mid-Atlantic Ridge (MAR) 16dg38′N area in 2006. The chemical compositions of background metalliferous and ore (ore-bearing) carbonate sediments are presented and inter-element correlations are examined. Individual episodes are distinguished in the accumulation history of the ore-bearing and metalliferous sediments on the basis of element factor analysis. © 2012 Pleiades Publishing, Ltd.
Alexeev N.L.,Polar Marine Geological Research Expedition |
Zinger T.F.,Russian Academy of Sciences |
Glebovitsky V.A.,Russian Academy of Sciences |
Kapitonov I.N.,Karpinskii Russian Geological Research Institute
Doklady Earth Sciences | Year: 2010
This report presents the main results of LA-ICPMS studies of zircon from metamorphosed magmatic rocks of the Fisher Massif in East Antarctica. The minimum age of crystallization for still unexplored granitoid intrusion in the southeastern part of the massif amounts to 1399 ± 11 Ma. The presence of inherited zircon of 1786 ± 23 Ma age in the rocks points to their fusion from a crustal source of Paleoproterozoic age. The time of the eruption of vulcanites of basite composition amounts to 1244 ± 11 Ma. The vulcanites contain xenogenic zircon of Late Archean and Middle Proterozoic age; hence, their initial melt interacted with the heterogeneous continental crust. The earliest metamorphism of the amphibolite facies proceeded 1213 ± 16 Ma ago, and was accompanied with intense shift deformations. The time of volcanism complies with the age of a large basite dike swarm in Vestfold Hills, intruded about 1250 Ma ago, which is associated with the destruction of the hypothetical Paleoproterozoic Nuna (Columbia) continent. © 2010 Pleiades Publishing, Ltd.