NE Svalbard Research Articles

Glacial and environmental changes in northern Svalbard over the last 16.3 ka inferred from neodymium isotopes

The reconstruction of past ice sheet extents and dynamics in polar regions is essential for understanding the global climate system and obtaining more reliable predictions of future climate change. Here, we present a multi-proxy dataset integrating the Nd isotopic compositions (ε Nd ) of paired detrital and authigenic Fe oxide fractions, grain size distributions, organic geochemistry, and mineral assemblages in a glacimarine sediment core (core HH17–1085-GC) retrieved from the continental shelf off northern Svalbard. Our results indicate variability in sediment provenance and chemical weathering patterns since the last deglaciation, allowing us to distinguish a succession of distinct paleoclimate events: 1) a general retreat of the Svalbard-Barents Sea Ice Sheet (SBIS) from the continental shelf before ca. 16.3 ka BP; 2) an intense episode of meltwater discharge related to massive glacier loss between ca. 12.1–9.9 ka BP; and 3) a period of reduced meltwater input between ca. 9.9 and 2.7 ka BP followed by 4) a phase of glacier re-advance over the last two millennia. Evidence for the prolonged supply of radiogenic detrital ε Nd and dolomite at the site of core HH17–1085-GC indicates that the onset of deglaciation offshore northeastern Svalbard may have occurred at least 1 ka later than that at the northwestern shelf, which can be further evaluated by obtaining a more precise end-member determination for the northeastern source with a quantitative ε Nd dataset from Nordaustlandet. In the context where both polar sea-ice and oceanic circulation are expected to have played minor roles in determining the sedimentary ε Nd compositions, the evidence for pronounced Nd isotopic decoupling between paired authigenic and detrital signatures (Δε Nd ) at ca. 15.2 and 14.1 ka BP is interpreted as reflecting chemical weathering changes following the retreat of the SBIS on northern Svalbard, probably corresponding to punctual episodes of glacial re-advances. Our findings provide a better understanding of the deglacial history of northern Svalbard during and after the last deglaciation and highlight the utility of Nd isotopes as a proxy for reconstructing paleo-cryosphere changes. • Ice recession from the continental shelf off northern Svalbard began before 16.3 ka BP. • Deglaciation of NE Svalbard may have started ~1 ka later than NW Svalbard. • Ice recession on N. Svalbard was punctuated by glacier re-advances at 15.2 and 14.1 ka BP. • Influence of the Arctic sea-ice and oceanic inflow on ε Nd in N. Svalbard was likely minor. • Δε Nd can be a useful tracer to reconstruct detailed glacial activity.

Air temperature conditions in northern Nordaustlandet (NE Svalbard) at the end of World War II

This article presents the results of an investigation into air temperature conditions in northern Nordaustlandet (NE Svalbard) based on meteorological observations made by German soldiers towards the end of World War II (1944/1945) and 4 months after its end. Traditional analysis using mean monthly data was supplemented by a detailed analysis based on daily data: maximum temperature, minimum temperature and diurnal temperature range. The latter kind of data made it possible to study such aspects of climate as the number of “characteristic days” (i.e., the number of days with temperatures exceeding specified thresholds), day‐to‐day temperature variability, and duration, onset and end dates of thermal seasons. The results from Nordaustlandet for the warmest period of the early 20th century warming period (ETCWP) were compared with temperature conditions both historical (the end part of the Little Ice Age) and contemporary (different sub‐periods taken from the years 1981–2017) to estimate the range of warming during the ETCWP.Analysis reveals that the expedition year 1944/1945 in Nordaustlandet was, in the majority of months, the warmest of all analysed periods, that is, both historical and contemporary periods. The study period was markedly warmer than 1981–2010 (mean annual −6.5 vs. −8.4 °C) but colder than the periods 2011–2016 (−5.7 °C) and 2014–2017 (−5.8 °C). The majority of mean monthly air temperatures in the ETCWP lies within two standard deviations of the modern 2014–2017 mean. This means that values of air temperature in the study period lie within the range of recent temperature variability. All other thermal characteristics show changes in accordance with expectations associated with general warming of the Arctic (i.e., a decrease in diurnal temperature range and number of cold days, and an increase in number of warm days). The latter days were most common in the ETCWP.

Discussion of “Depositional ages and provenance of the Neoproterozoic Damara Supergroup (northwest Namibia): Implications for the Angola–Congo and Kalahari cratons connection” by Débora B. Nascimento, Renata S. Schmitt, André Ribeiro, Rudolph A. J. Trouw, Cees W. Passchier, and Miguel A. S. Basei

Discussion of “Depositional ages and provenance of the Neoproterozoic Damara Supergroup (northwest Namibia): Implications for the Angola–Congo and Kalahari cratons connection” by Débora B. Nascimento, Renata S. Schmitt, André Ribeiro, Rudolph A. J. Trouw, Cees W. Passchier, and Miguel A. S. Basei

Conodont biostratigraphy in the Early to Middle Ordovician strata of the Oslobreen Group in Ny Friesland, Svalbard

The remotely located Cambro-Ordovician strata in Ny Friesland, NE Spitsbergen, Svalbard, are referred to the Oslobreen Group, which is composed of the Tokammane, Kirtonryggen and Valhallfonna formations. Herein we record the conodont succession of the Kirtonryggen and Valhallfonna formations. Collections of well-preserved conodonts (CAI 1) have been recovered from the Lower to lower Middle Ordovician interval in the region. Eight regional conodont zones are established in this preliminary study of the Oslobreen Group exposed at Hinlopenstretet, NE Svalbard. In ascending order these zones are: Rossodus manitouensis, Macerodus dianae, Oneotodus costatus, Oepikodus communis, O. evae, O. intermedius, Periodon aff. flabellum-Periodon hankensis and Periodon macrodentatus. The yield is relatively poor for the Kirtonryggen Formation, but the oldest Ordovician conodont faunas span the Tremadocian Rossodus manitouesis through Macerodus dianae zones followed by the Floian Oepikodus communis Zone. The taxa are typical of the tropical North American Midcontinent faunal province that dominated the region until open marine associations invaded the shallow shelf (i.e. Evae transgression). The pandemic Oepikodus evae becomes frequent and is succeeded by O. intermedius in abundance in the lower Valhallfonna Formation (Olenidsletta Member). The upper strata are characterised by the Periodon-Paroistodus assemblage characteristic for outer shelf and slope environments around Laurentia. In total, this formation comprises the Floian and Dapingian stages and ends in the early Darriwilian Periodon macrodentatus Zone in this region. The Ny Friesland faunas show affinities to coeval assemblages from Northeast Greenland and West Newfoundland. (Less)

Cryogenian glaciations on the southern tropical paleomargin of Laurentia (NE Svalbard and East Greenland), and a primary origin for the upper Russøya (Islay) carbon isotope excursion

Neoproterozoic successions in NE Svalbard and East Greenland host a pair of glacigenic formations, the younger of which are correlated with the terminal Cryogenian (Marinoan) glaciation based on their lithologically and isotopically diagnostic cap dolostones. A deep negative carbon isotope excursion (CIE) occurs stratigraphically beneath the older glacigenic formations in both areas, but no CIE is preserved beneath the younger glacial horizon in either area. This led to uncertainty over the age of the CIE and the paleoenvironmental significance of the units separating the glacigenic formations. 87Sr/86Sr ratios in Sr-rich limestone associated with the CIEs are ≤0.7064 in East Greenland and ≤0.7068 in NE Svalbard, consistent with early Cryogenian values globally and inconsistent with late Cryogenian ratios, which are exclusively ≥0.7071. The CIEs are tentatively correlated with the Islay excursion in the Scottish and Irish Caledonides, and potentially correlative subglacial CIEs in northwestern Canada, northwestern Tasmania and the southwestern United States. In NE Svalbard, newly-acquired δ13Corg data covary with δ13Ccarb across the CIE, but the organic excursion is roughly half the amplitude of the inorganic excursion. δ13Ccarb and δ18Ocarb do not covary, nor does δ13Corg vary as a function of total organic carbon content. A primary origin for the CIE is supported and the accompanying proliferation of stromatolites suggests rising carbonate saturation (falling pCO2) prior to glaciation. New data suggest that the hiatus responsible for the missing Trezona CIE occurs at the top, not the bottom, of the Bråvika member sandstone in NE Svalbard. A dramatic decline in regional average thickness of older Cryogenian glacial deposits from the paleomagnetically-determined subtropics (British Isles) to the deep tropics (Svalbard) is consistent with meteoric net accumulation and sublimation zones on a snowball Earth, and inconsistent with the Jormungand climate zonation.

Environmental change in the Early Permian of NE Svalbard: from a warm-water carbonate platform (Gipshuken Formation) to a temperate, mixed siliciclastic-carbonate ramp (Kapp Starostin Formation)

A detailed facies study of Early Permian strata within NE Svalbard reveals a fundamental change of the depositional setting, from a restricted-marine, warm-water carbonate platform to an open-marine, temperate-water, mixed siliciclastic-carbonate ramp. The uppermost strata of the Gipshuken Formation (Templet and Sorfonna members; Sakmarian–early Artinskian?) consist of microbialites (algal mats), mudstones, bioclastic/peloidal limestones, carbonate breccias and Microcodium facies reflecting peritidal platform areas and supratidal sabkhas. A mixed heterozoan/reduced photozoan assemblage indicates temperate-water conditions within neighboring deeper, open-marine mid-platform areas, while warm-water conditions still prevailed within inner platform zones. In contrast, the lowermost strata of the overlying Kapp Starostin Formation (Voringen Member; late Artinskian?–Kungurian) show a fully heterozoan biotic assemblage reflecting temperate water conditions within open-marine, storm-dominated, nearshore to transitional offshore areas of a mixed carbonate-siliciclastic ramp. The Voringen Member comprises three facies associations, which form a shallowing-upward sequence subsequent to an initial transgression. The sediments reflect bryozoan bioherms in most distal areas, followed by stacked tempestites of sandy brachiopodal shell banks and Skolithos piperocks, grading into broad sand flats in most proximal areas of the inner ramp. The above environmental change is regarded as a regional event taken place across the entire shelf along the northern margin of Pangea and is attributed to paleoclimatic, paleoceanographic, as well as paleogeographic changes, possibly related to the overall northwards drift of the supercontinent. An abrupt increase in terrigenous input coinciding with this change is ascribed to the uplift of a new local source area, probably to the north or east of the investigation area.

Timing of migmatization and granite genesis in the Northwestern Terrane of Svalbard, Norway: implications for regional correlations in the Arctic Caledonides

Abstract: U–Pb ion microprobe investigations of zircons from gneisses, granites and migmatites of the pre-Devonian Smerenburgfjorden and Richarddalen Complexes constrain the tectonic evolution and origin of Svalbard's Northwestern Terrane. Field relationships combined with U–Pb age data indicate that a late Meso- to Neoproterozoic metapelitic protolith was intruded by Tonian ( c . 960 Ma) granitoids and suggest that the entire Northwestern Terrane is underlain by early Neoproterozoic granitoids intruding older metasediments. Both rock types were later involved in Caledonian deformation, with subsequent migmatization and granite genesis at c . 435–420 Ma. Ages of inherited zircons in granites and migmatites reflect anatexis of this late Meso- to Neoproterozoic protolith, with zircon xenocrysts ranging in age from c . 1030 to 1820 Ma. Pronounced lithological, geochronological and tectonothermal similarities to NE Svalbard (Nordaustlandet) and the Krummedal supracrustal sequence of East Greenland suggest a strong correlation between Svalbard and East Greenland prior to Caledonian orogenesis. Supplementary material: Ion microprobe analytical methods, data table and zircon descriptions are available at http://www.geolsoc.org.uk/SUP18326 .

Grenvillian and Caledonian tectono-magmatic activity in northeasternmost Svalbard

Abstract The Nordaustlandet Terrane of NE Svalbard forms an exposed part of the Barentsia microcontinent. Augen gneisses, migmatites, granites and gabbros dominate the scattered outcrops along the northeastern coast of Nordaustlandet, and on the smaller islands to the north and east, as far as Kvitøya. These outcrops probably represent the deepest exposed crustal levels within the folded Caledonian basement of the Nordaustlandet Terrane. In the present study, a variety of rock types have been analysed by different U-Pb dating techniques (conventional, Pb-evaporation and ion microprobe) on zircon, titanite and monazite The major and trace element compositions and Sm-Nd isotope geochemistry of these rocks have also been investigated. The augen gneisses yield U-Pb ages of c. 950 Ma, indicating that they are deformed late Grenvillian granites, similar to the Grenville-age granites and augen gneisses of northwestern and central Nordaustlandet. Migmatites, grey granites, aplitic dykes and a syenite (boulder) yield U-Pb ages mainly falling in the 430–450 Ma range, slightly older than the 410–420 Ma late-tectonic Caledonian granites further west. Both the Grenvillian and Caledonian granites are of crustal anatectic origin, and the Caledonian granites and migmatites may have formed largely by remelting of Grenvillian crust. The ages of the mafic rocks are uncertain, but Sm-Nd data indicate a possible emplacement age of c. 700 Ma for two of the gabbros, suggesting that they may be the result of rift-related magmatism in connection with the opening of the Iapetus Ocean. A few enigmatic inherited zircons of similar late Neoproterozoic age found in younger granites may possibly be related to this event. No evidence for late Neoproterozoic orogenic activity, similar to that in the Timanides of northern Russia, is seen in eastern Svalbard. At this time, eastern Svalbard (Barentsia) was probably part of the Laurentian margin, and probably located far away from northern Baltica.

Bioaccumulation of radiocaesium in Arctic seals

Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82°N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of 137Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23±0.045 Bq/kg f.w. 137Cs concentrations in both liver and kidney samples were near detection limits (≈0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of 137Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed.

Neoproterozoic chemostratigraphy and correlation of the Port Askaig glaciation, Dalradian Supergroup of Scotland

The δ 13 C of preglacial carbonates beneath the glaciogenic Port Askaig Formation falls from +5‰ to negative values, while least-altered 87 Sr/ 86 Sr values are close to 0.7067. Postglacial ‘cap carbonates’ of the Bonahaven Formation begin with negative δ 13 C carb values, jumping sharply to +11.7‰ near the top, which we correlate with excursions above the Elbobreen–Wilsonbreen glaciations of Svalbard and putative Sturtian (not Varanger) glaciations elsewhere, dated at c. 720 Ma. Much of the succeeding Terminal Neoproterozoic is missing in NE Svalbard and East Greenland, raising doubts about their use for global Sr and C isotope curves in the Neoproterozoic.

Vendian basin evolution in East Greenland and NE Svalbard

In order to help focus new biostratigraphic and chemostratigraphic work, the sedimentology and stratigraphy of Vendian successions in central East Greenland and NE Svalbard (NE Spitsbergen and Nordaustlandet) are reviewed. These areas originally formed part of a contiguous sedimentary basin as illustrated by comparison of two measured sections, 750 m thick, in which a number of matching divisions occur. At the base, a carbonate platform succession (“bed-group 20” in Greenland, Elborbreen Formation member E1 in Spitsbergen) is followed by two discrete glacial facies associations separated by non-glacial sediments (Ulvesø, Arena and Storeelv Formations of Greenland and members E2, E3–E4 and the Wilsonbreen Formation of Spitsbergen), and a transgressive shale succession (Canyon Formation and Dracoisen Formation, respectively) with basal dolostone. Whereas NE Spitsbergen displays a further 300 m of section within the Dracoisen Formation, mostly of probable playa lake facies, in Greenland a 50-m-scale regressive dolostone unit (upper Canyon Formation) is capped by only 20 m of lacustrine facies (Spiral Creek Formation). In each case, lower Cambrian sandstones rest on the Vendian sections. Later Vendian times (Ediacaran interval) seem to be virtually unrepresented by marine strata. Reconstruction of the stratigraphic architecture along the 180 km N S outcrop belt in NE Svalbard and the 300 km N S belt in East Greenland reveals few lateral changes because of an orientation nearly parallel to the depositional strike. Syn-depositional faulting apparently controlled accelerated subsidence in the East Greenland area, leading to the development of carbonate slope facies (“bed-group 19”), either overlain locally by “bed-group 20”, or conformably overlain by glacimarine deposits. A section towards the southeastern limit of the basin in East Greenland, in Canning Land, shows the glacigenic Storeelv Formation resting on a major erosion surface on platform carbonates. In the far southwest, it rests directly on basement; this represents the main source area of sediments in the basin. The upper Canyon Formation shows evidence of progradation from the south. Chronostratigraphic interpretation of the succession leads us to the belief that the base of each glacial unit represents a sequence boundary, although only limited erosion occurred within the main outcrop belt. A sequence boundary may also be present at the base of the Elbobreen Formation. Submarine erosion must have led to a slight hiatus at the close of the second glaciation, temporally following but spatially coincident with a sequence boundary. The upper Canyon Formation is probably a highstand systems tract and the overlying base of the Spiral Creek Formation is a sequence boundary. The transgressive base of the Cambrian sandstones overprints another sequence boundary, at least in Greenland.

Meiobenthic stocks and benthic activity on the NE-Svalbard shelf and in the Nansen Basin

High Arctic meiofaunal distribution, standing stock, sediment chemistry and benthic respiratory activity (determined by sediment oxygen consumption using a shipboard technique) were studied in summer 1980 on the NE Svalbard shelf (northern Barents Sea) and along a transect into the Nansen Basin, over a depth range of 240–3920 m. Particulate sediment proteins, carbohydrates and adenylates were measured as additional measures of benthic biomass. To estimate the sedimentation potential of primary organic matter, sediment bound chloroplastic pigments (chlorophylls, pheopigments) were assayed. Pigment concentrations were found comparable to values in sediments from the boreal and temperate N-Atlantic. Meiofauna, which was abundant on the shelf, decreased in numbers and biomasses with increasing depth, as did sediment proteins, carbohydrates, adenylates and sediment oxygen consumption. Meiofaunal abundances and biomasses within the Nansen Basin were comparable with those observed in abyssal sediments of the North Atlantic. Nematodes clearly dominated in metazoan meiofauna. Protozoans were abundant in shelf sediments. Probably in response to the sedimentation of the plankton bloom, meiofauna abundance and biomass as well as sediment proteins, carbohydrates and adenylates were significantly correlated to the amount of sediment bound chloroplastic pigments, stressing the importance of food quantity to determine benthic stocks. Ninety-four percent of the variance in sediment oxygen consumption were caused by chloroplastic pigments. Benthic respiration, calculated per unit biomass, was 3–10 times lower than in the East Atlantic, suggesting low turnover rates in combination with a high standing stocks for the high Arctic benthos.

Correlation of Late Proterozoic tillites in the North Atlantic region and Europe

SummaryWell-established Late Proterozoic tillites are widely distributed in Svalbard, East and North Greenland, the Norwegian and Swedish Caledonides, Scotland, northwestern Ireland, western USSR, the Urals, Newfoundland and the Appalachians. Recent biostratigraphic and geochronometric data have provided the following sequence of glacial events. The earliest evidence of glaciation is represented by tillites in Newfoundland, Scotland and possibly NE Svalbard, and may have taken place in Late Riphean (sensuVidal) or Sturtian (sensuHarland) time, perhapsc.800 Ma ago. A glacial period in Vendian time, the Varangian, centred on 650 Ma was a much more severe climatic event, represented in all the above mentioned areas except Newfoundland. Two Varangian glacial epochs are recorded in Svalbard, East Greenland, northern Norway and possibly western USSR, and although most of the deposits are marine, terrestrial conditions prevailed in some areas with associated periglacial phenomena. The earlier epoch was completed before 650 Ma; the later one occurred within the rangec.650–610 Ma.A tectonic reconstruction of the region places eastern Svalbard adjacent to East Greenland, which has implications for major strike-slip motions in late and post-Caledonian times. A discrete ice-sheet is envisaged, centred on the western USSR (terrestrial tillites) with ice flowing out to the then peripheral area of the northwestern Europe continental margin and to the Urals where shallow platformal glaciomarine sediments accumulated.