East Svalbard Research Articles

Combined paleomagnetic, isotopic, and stratigraphic evidence for true polar wander from the Neoproterozoic Akademikerbreen Group, Svalbard, Norway

Research Article| September 01, 2006 Combined paleomagnetic, isotopic, and stratigraphic evidence for true polar wander from the Neoproterozoic Akademikerbreen Group, Svalbard, Norway Adam C. Maloof; Adam C. Maloof 1Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Search for other works by this author on: GSW Google Scholar Galen P. Halverson; Galen P. Halverson 1Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Search for other works by this author on: GSW Google Scholar Joseph L. Kirschvink; Joseph L. Kirschvink 2Division of Geological and Planetary Sciences, California Institute of Technology 170-25, 1200 East California Boulevard, Pasadena, California 91125, USA Search for other works by this author on: GSW Google Scholar Daniel P. Schrag; Daniel P. Schrag 3Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Search for other works by this author on: GSW Google Scholar Benjamin P. Weiss; Benjamin P. Weiss 4Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA Search for other works by this author on: GSW Google Scholar Paul F. Hoffman Paul F. Hoffman 5Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Adam C. Maloof 1Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Galen P. Halverson 1Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Joseph L. Kirschvink 2Division of Geological and Planetary Sciences, California Institute of Technology 170-25, 1200 East California Boulevard, Pasadena, California 91125, USA Daniel P. Schrag 3Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Benjamin P. Weiss 4Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA Paul F. Hoffman 5Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Publisher: Geological Society of America Received: 28 Aug 2005 Revision Received: 27 Apr 2006 Accepted: 30 Apr 2006 First Online: 08 Mar 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 Geological Society of America GSA Bulletin (2006) 118 (9-10): 1099–1124. https://doi.org/10.1130/B25892.1 Article history Received: 28 Aug 2005 Revision Received: 27 Apr 2006 Accepted: 30 Apr 2006 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Adam C. Maloof, Galen P. Halverson, Joseph L. Kirschvink, Daniel P. Schrag, Benjamin P. Weiss, Paul F. Hoffman; Combined paleomagnetic, isotopic, and stratigraphic evidence for true polar wander from the Neoproterozoic Akademikerbreen Group, Svalbard, Norway. GSA Bulletin 2006;; 118 (9-10): 1099–1124. doi: https://doi.org/10.1130/B25892.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract We present new paleomagnetic data from three Middle Neoproterozoic carbonate units of East Svalbard, Norway. The paleomagnetic record is gleaned from 50 to 650 m of continuous, platformal carbonate sediment, is reproduced at three locations distributed over >100 km on a single craton, and scores a 5–6 (out of 7) on the Van der Voo (1990) reliability scale. Two >50° shifts in paleomagnetic direction are coincident with equally abrupt shifts in δ13C and transient changes in relative sea level. We explore four possible explanations for these coincidental changes: rapid plate tectonic rotation during depositional hiatus, magnetic excursions, nongeocentric axial-dipole fields, and true polar wander. We conclude that the observations are explained most readily by rapid shifts in paleogeography associated with a pair of true polar wander events. Future work in sediments of equivalent age from other basins can test directly the true polar wander hypothesis because this type of event would affect every continent in a predictable manner, depending on the continent's changing position relative to Earth's spin axis. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Spatial variability of phytoplankton, nutrients and new production estimates in the waters around Svalbard

Phytoplankton dynamics and carbon input into Arctic and sub-Arctic ecosystems were investigated around Svalbard, in summer 1991. Phytoplankton biomass, species composition and dissolved nutrient concentrations were analysed from water samples collected along seven transects. Phytoplankton biomass was low especially to the north (Chlorophyll-a mean 0.3 pg 1- '), where flagellates dominated the communities and only ice-diatoms were present. To the west, the phytoplankton composition was representative of a summer Atlantic community, in a post-bloom state. Zooplankton grazing, mainly by copepods, appeared to be the main control on biomass to the west and north of Svalbard. In the Barents Sea (east of Svalbard), an ice edge bloom was observed (Chlorophyll-a max. 6.8 pgl-') and the ice edge receded at a rate of approximately 1 1 km day-'. The phytoplankton community was represented by marginal ice species, especially Phaeocystis poucherii and Chaeroceros socialis. South of the ice edge, Deep Chlorophyll Maxima (DCM) were observed, as surface waters became progressively nutrient-depleted. In these surface waters, the phytoplankton were predominantly auto- and heterotrophic flagellates. Carbon production measurements revealed high net production (new and regenerated) to the north of the Barents Sea Polar Front (BSFW); it was especially high at the receding ice edge (reaching 1.44gC m-'day-'). To the south, a low level of production was maintained, mainly through regenerative processes.

Spatial variability of phytoplankton, nutrients and new production estimates in the waters around Svalbard

Phytoplankton dynamics and carbon input into Arctic and sub-Arctic ecosystems were investigated around Svalbard, in summer 1991. Phytoplankton biomass, species composition and dissolved nutrient concentrations were analysed from water samples collected along seven transects. Phytoplankton biomass was low especially to the north (Chlorophyll-a mean 0.3 pg 1- '), where flagellates dominated the communities and only ice-diatoms were present. To the west, the phytoplankton composition was representative of a summer Atlantic community, in a post-bloom state. Zooplankton grazing, mainly by copepods, appeared to be the main control on biomass to the west and north of Svalbard. In the Barents Sea (east of Svalbard), an ice edge bloom was observed (Chlorophyll-a max. 6.8 pgl-') and the ice edge receded at a rate of approximately 1 1 km day-'. The phytoplankton community was represented by marginal ice species, especially Phaeocystis poucherii and Chaeroceros socialis. South of the ice edge, Deep Chlorophyll Maxima (DCM) were observed, as surface waters became progressively nutrient-depleted. In these surface waters, the phytoplankton were predominantly auto- and heterotrophic flagellates. Carbon production measurements revealed high net production (new and regenerated) to the north of the Barents Sea Polar Front (BSFW); it was especially high at the receding ice edge (reaching 1.44gC m-'day-'). To the south, a low level of production was maintained, mainly through regenerative processes.

Structural elements and petroleum geology of the Norwegian sector of the northern Barents Sea

The northern Barents Sea is divided into two principal prospective provinces: (1) the platform areas south and east of Svalbard contain possible hydrocarbon plays in Upper Palaeozoic clastics and carbonates, and in Mesozoic sandstones; (2) The Barents Sea margin, which includes the Yermak Plateau, with possible plays in late Mesozoic and Tertiary sandstones. The platform areas are underlain by a Palaeozoic rift system of highs and intervening basins, containing Devonian and Early Carboniferous rocks overlain by relatively flat-lying sequences of Late Palaeozoic and Mesozoic age. The Barents Sea margin is a complex basin province formed in response to phases of the Late Mesozoic and Cenozoic break-up of the Pangea supercontinent, and subsequent seafloor spreading west of Spitsbergen. The northern Barents Sea is as yet not open for commercial exploration, and no deep wells have been drilled in the offshore areas. It is one of the largest remaining frontier areas in western Europe and as such affords a wide range of exploration opportunities. However, the area is considered to be of high risk for petroleum exploration, with generally low statistical probabilities of discovery, largely because of the limited amount of data available to evaluate potential hydrocarbon plays, and in particular the presence, distribution, quality and maturity of source rocks. Hydrocarbon resource estimates are therefore characterized by large uncertainties. Potential reservoir rocks are identified, and seismic mapping has revealed many structural and stratigraphic leads on the Sentralbanken High, the Kong Karls Land Platform, the Gardarbanken High and in the Mesozoic and Tertiary sub-basins northwest of Bjørnøya. Future challenges will be focused on reducing uncertainties in mapping the distribution of source rocks of suitable quality. Limited basin modelling studies indicate that oil may have been generated and accumulated in many provinces, but better constrained models are required to evaluate Early Cretaceous thermal events and Late Cenozoic uplift processes that may have had negative effects on both oil generation and the retention of hydrocarbons in traps.

Reproduction and larval ecology of the Arctic fish speciesArtediellus atlanticus (Cottidae)

State of maturity, egg numbers, as well as gonadosomatic index (GSI), and relative fecundity were determined in 209 females of the cottid speciesArtediellus atlanticus. Specimens were caught by Agassiz and bottom trawls during two expeditions of RV “Polarstern” to the shelf off northeast Greenland (ARK VII/2; July/August 1990) as well as to the Barents Sea and the shelf areas surrounding Svalbard (ARK VIII/2 — Arctic EPOS; June/July 1991). Analysis of the state of maturity showed thatA. atlanticus spawns from late summer to autumn. Individuals from northern populations spawn later (November) than those from more southern locations (July to September). The total number of eggs (40–216) was small due to their large diameter and the small size of the fish. The mean GSI of females from the central Barents Sea (36.9±6.5%;n=24) was significantly higher (P<0.001) than the GSI of females caught off eastern Svalbard (18.7±4.0%;n=14), compared at stage IV of maturity. The mean relative fecundity was significantly higher (P<0.001) for females of the central Barents Sea (17.9±2.3;n=19) than for females caught on more northern stations east of Svalbard (6.9±1.8;n=17) and north of Svalbard (6.4±0.5;n=7). Individuals ofA. atlanticus that were maintained at 0°C spawned in the aquaria, allowing observation of the development of their eggs and larvae for 1 year. The eggs needed more than 200 days to develop. The larvae hatched at a very advanced stage and were similar to the adults in appearance and behaviour. The larvae grew at a rate of 0.02 mm per day and showed a benthic mode of life.

Organic carbon, carbonate, and clay mineral distributions in eastern central Arctic Ocean surface sediments

Results from a detailed sedimentological investigation of surface sediments from the eastern Arctic Ocean indicate that the distribution of different types of sediment facies is controlled by different environmental processes such as sea-ice distribution, terrigenous sediment supply, oceanic currents, and surface-water productivity. In comparison to other open-ocean environments, total organic carbon contents are high, with maximum values in some deep-basin areas as well as west and north of Svalbard. In general, the organic carbon fraction is dominated by terrigenous material as indicated by low hydrogen index values and high C/N ratios, probably transported by currents and/or sea ice from the Eurasian Shelf areas. The amount of marine organic carbon is of secondary importance reflecting the low-productivity environment described for the modern ice-covered Arctic Ocean. In the area north of Svalbard, some higher amounts of marine organic matter may indicate increased surface-water productivity controlled by the inflow of the warm Westspitsbergen Current (WSC) into the Arctic Ocean and reduced sea-ice cover. This influence of the WSC is also supported by the high content of biogenic carbonate recorded in the Yermak Plateau area. The clay mineral distribution gives information about different source areas and transport mechanisms. Illite, the dominant clay mineral in the eastern central Arctic Ocean sediments, reaches maximum values in the Morris-Jesup-Rise area and around Svalbard, indicating North Greenland and Svalbard to be most probable source areas. Kaolinite reaches maximum values in the Nansen Basin, east of Svalbard, and in the Barents Sea. Possible source areas are Mesozoic sediments in the Barents Sea (and Franz-Josef-Land). In contrast to the high smectite values determined in sea-ice samples, smectite contents are generally very low in the underlying surface sediments suggesting that the supply by sea ice is not the dominant mechanism for clay accumulation in the studied area of the modern central Arctic Ocean.

Diet of Ringed Seals (&lt;i&gt;Phoca Hispida&lt;/i&gt;) in a Fjord of West Svalbard

Stomachs of 134 ringed seals from West Svalbard (Kongsfjorden) and East Svalbard (drift ice) were examined. Twenty-four prey taxa were found. The most important items were arctic cod (Boreogadus saida), shrimp (Pandalus borealis), krill (Thysanoessa inermis) and the amphipod Themisto libellula. In spring young redfish (Sebastes sp.) was an important food item; in summer seals fed on dense aggregations of krill in front of glaciers. Mysids, amphipod crustaceans and small size classes of coastal fish species were abundant in Kongsfjorden, but seals take them as secondary food items only.Key words: ringed seals, Phoca hispida, arctic food web, fjord ecology, Svalbard, prey taxa

Arcella ovaliformis sp. nov., a New Testate Amoeba from Edgeøya, a High Arctic Island

Summary Arcella ovaliformis sp. nov. is described from mosses collected on Edgeoya (South East Svalbard). Besides a description, information is given on its ecology and the communities it occurs.

Respiration and excretion rates of Calanus glacialis in arctic waters of the Barents Sea

The respiration and excretion rates of Calanus glacialis (Jaschnov) Copepodite Stages III, IV, V, and adult females from the drift-ice area east of Svalbard (Barents Sea) were measured in shipboard experiments during the period from 27 May to 13 June, 1983. The phytoplankton biomass and abundance varied considerably between localities, but these variations were not generally reflected in the respiration and excretion rates of the copepod. The respiration and excretion rates of C. glacialis at the ambient temperature of-1.8°C (average respiration rates of 0.95, 0.73, 0.57, and 0.60 μl O2 mg-1 dry wt h-1 for Copepodite Stage III, IV, V, and adult females, respectively) were similar to those previously reported for other large-sized copepods from cold or temperate areas. Average respiration and excretion rates tended to decrease with incubation time or time after capture. Measurements on ten occasions within a period of 27 h after capture revealed excretion rates of ammonium ranging between 2.9 and 16.8 for C III, 3.7 and 21.1 for C IV, 1.3 and 28.4 for C V, and 1.6 and 18.7 for adult females, all expressed as nmol mg-1 dry wt h-1. In all experiments, excretion rates of inorganic phosphate varied between 0.7 and 1.5 (C III), 0.5 and 1.1 (C IV), 0.2 and 0.8 (C V), and 0.3 and 1.0 (adult females) nmol mg-1 dry wt h-1. Ratios of O:N, O:P, and N:P indicated that much of the metabolic energy was derived from catabolism of proteins. Comparison of the turnover rate of carbon and nitrogen showed, however, that nitrogen turnover was between 2.6 and 8.9 times higher than that of carbon. This may indicate that the copepods deaminate ingested protein, with the carbon skeleton of the amino acids subsequently being used in the synthesis of lipid compounds, possibly wax esters.

The Arctic Caledonides and earlier Oceans

SummaryConsideration of the arctic configuration of the Caledonides leads to a distinction between eastern and western geosynclinal belts. The western belt, comprising the East Greenland, East Svalbard and southern Barents Sea Caledonides is postulated to continue northwards into the Lomonosov Ridge, whilst the western Spitsbergen Caledonides are thought to have originated as part of the North Greenland geosyncline which is also thought to continue northwards to form the western part of the Lomonosov Ridge. The eastern Caledonian geosynclinal belt comprising the Scandinavian Caledonides appears to swing eastwards to link with the Timan Chain and possibly the Urals.The already postulated (‘Proto-Atlantic’) ocean concept is reviewed in the light of the Arctic Caledonides and named Iapetus. Faunal provincialism suggests that the ocean was in existence up to early Ordovician but had substantially closed by mid Ordovician times. Possible relics of the suture marking the closure of this ocean suggest that it lay to the west of the Arctic Scandinavian Caledonides trending NE to latitude 70° N and thence veered eastwards separating the southern Barents Sea Caledonides from those of Arctic Scandinavia, possibly connecting with the northern Uralian ocean. A previous branch of the ocean may have separated East Svalbard and East Greenland as an ocean-like trough. A further (pre-Arctic) ocean may have existed to the north of the North Greenland–Lomonosov Ridge geosynclines. This is named Pelagus.The closure of these oceanic areas and the deformation of the bordering geosynclines delineates three principal continental plates, namely, Baltic, Greenland and Barents Plates. Their relative dominantly E–W motion up to Silurian times produced compression between the Greenland and both the Baltic and Barents plates but dextral transpression and transcurrence between the latter plates. In Late Silurian to Devonian times an increasing northward component controlled late Caledonian transpression and sinistral transcurrence between the Greenland plate and the combined Baltic and Barents plates.