Ellef Ringnes Island Research Articles

The Silent VOICE—Searching for Geochemical Markers to Track the Impact of Late Jurassic Rift Tectonics

AbstractA causal mechanism for the Volgian Isotopic Carbon Excursion (VOICE) remains enigmatic. Elemental geochemical profiles of the Deer Bay Formation, Sverdrup Basin, Arctic Canada that record the VOICE and contemporaneous strata are herein examined to provide insight into depositional environments during Late Jurassic‐Early Cretaceous time. Silver (Ag) and Cadmium (Cd) are enriched across the VOICE at localities on Axel Heiberg Island, and in Tithonian (∼Volgian) strata of Ellef Ringnes Island. Other redox‐sensitive trace elements do not exhibit spatially or temporally consistent patterns and indicate oxic conditions. A lack of relationship across the VOICE between Ag and the quality, quantity, and isotopic composition of organic matter suggests that the negative isotope excursion and interval of Ag enrichment are not merely functions of changes in organic matter source or amount, while a lack of spatially consistent change in geochemical indices of weathering similarly excludes climate change and/or sediment provenance as a driver. Therefore, in a ventilated setting and without marked changes in organic matter content, Ag enrichment may be due to hydrothermal activity. Contemporaneous Ag enrichment in strata from Svalbard suggests that a source of hot fluid sufficient to produce Ag‐rich seawater may have been related to rifting in the adjacent proto‐Amerasia Basin. Hydrothermal activity may also have been a widespread source of isotopically depleted carbon. This work develops new geochemical fingerprints that may be used to trace the spatial extent of hydrothermal events that do not leave an extinction pattern but may nonetheless have a far‐reaching influence on biogeochemical systems.

Upper Paleozoic stratigraphy and detrital zircon geochronology along the northwest margin of the Sverdrup Basin, Arctic Canada: insight into the paleogeographic and tectonic evolution of Crockerland

The upper Paleozoic succession along the northwest margin of the Canadian Arctic Sverdrup Basin is little studied and poorly understood yet has the potential to yield insights into the paleogeographic and tectonic evolution of the Arctic regions including Crockerland. Carboniferous and Permian drill cuttings were collected from five exploration wells on Brock, Mackenzie King, and Ellef Ringnes islands. Seven unconformity-bounded sequences were identified and correlated. Reflection seismic interpreted on Ellef Ringnes Island indicates that a major syn-sedimentary fault offsets the Mississippian succession bounding a down-to-the-north half-graben. Late Pennsylvanian (Gzhelian) fault reactivation, associated with the Melvillian Disturbance, created a depression that extended northward and was bordered to the south by a structural high. Episodic minor fault reactivation occurred until the Early–Middle Permian boundary. During the latest Early Permian (Kungurian), sand derived from Crockerland prograded southward onto the Sverdrup Basin’s northwest margin and continued into the Roadian. After a lull during the Wordian, clastic progradation resumed in the Capitanian. Detrital zircon U–Pb ages recovered from Kungurian and Roadian samples on Brock and Ellef Ringnes islands display Devonian Clastic Wedge (DCW) signatures. A Moscovian–Artinskian carbonate blanket likely covered Crockerland and sheltered DCW material from erosion, implying it was a subsiding, carbonate bank throughout most of the Pennsylvanian – Early Permian. Base level fall in the Kungurian, associated with a transition to a more humid climate, breached these carbonate rocks to allow erosion and transportation of DCW material. Recycling of the DCW started earlier (Artinskian) and peaked later (Wordian) along the southern margin of the basin.

Diversity of igneous rocks from the Isachsen Dome, Ellef Ringnes Island, Canadian High Arctic

The sedimentary deposits of the central Sverdrup Basin on Ellef Ringnes Island were affected by both salt diapirism and igneous activity of the Cretaceous High Arctic Large Igneous Province (HALIP). Occurrences of mafic igneous rocks on the centre of salt domes are usually assigned to the Cretaceous magmatism. Petrographic, geochemical, Sr–Nd isotope, and geochronological (Ar–Ar dating) studies on six rock fragments collected on the top of Isachsen Dome reveal a larger variability in the composition and the age compared to HALIP-related rocks from elsewhere on Ellef Ringnes Island. A blocky fragment of tholeiitic hornblende dolerite with an Ar–Ar age of 121 Ma is interpreted to originate from an in-situ intrusion and was uplifted by evaporite diapirism. The other samples are small, sub-rounded pebbles, which represent three different parent rock types. A kaersutite-bearing alkali basalt was possibly formed during the Triassic or Permian. A leucocratic, albitised rock fragment has experienced contact metasomatism at 102 Ma, and three very similar tholeiitic basalt fragments probably derived from the margin of a dyke were auto-hydrothermally affected at 69 Ma. The inferred source area of these exotic pebbles is the segment of the Arctic continental margin in the northeast that was repeatedly affected by igneous events between the Carboniferous and latest Cretaceous and that was uplifted and eroded during the Eocene. The rock fragments were probably deposited as Palaeogene sediments above the rising Isachsen diapir shortly before or as the head of the salt dome has pierced the Earth’s surface. Glacial transport up the top of Isachsen Dome during the Late Wisconsinan glaciation is not very likely due to the contrast between the north to northwest directed ice-flow direction reported in the literature and the assumed northeastern source area of the pebbles; however, it cannot be completely excluded.

Influence of igneous intrusions on the thermal maturity of organic matter in the Sverdrup Basin, Arctic Canada

The influence of igneous intrusions on the trend of thermal maturity with depth in two drillholes, one on Ellesmere Island and the other on Ellef Ringnes Island, Arctic Canada, was assessed using vitrinite and solid bitumen reflectance, Rock-Eval pyrolysis/TOC, and gas composition analysis in order to assess the impact of igneous intrusions on the hydrocarbon system in the area. Thick sequences of Permo-Pennsylvanian strata in Sabine Peninsula, Melville Island, were intruded by two igneous intrusions in the Panarctic Chads Creek B-64 (influenced by one intrusion) and the Panarctic Drake Point D-68 (influenced by two intrusions). Sedimentary strata in Chads Creek B-64 were intruded by a 120 m-thick diabase sill (with temperature of ~1100 °C) of unknown age. This resulted in increased reflectance of vitrinite from 0.90% to 1.65% and of pyrobitumen from 2.90% to almost 5.80% near the sill contact at depth of 3600 m. Solid bitumen outside of the thermal aureole zones and having reflectance values <1.50% followed the extrapolated trend for solid bitumen present in the country rocks. In Panarctic Drake Point D-68, the intrusives are granodiorite sills of 45 m and 75 m thickness and were emplaced during the Upper Jurassic (152 Ma) and Lower Cretaceous (131 Ma). The intrusion temperature was 800 °C. The Vitrinite Rr prior to sill emplacement was <1.0% outside the aureole and increased to approximately 2.0% near the intrusive zone. The rocks were well-lithified prior to sill emplacement. Solid bitumen underwent carbonization after being exposed to a temperature of at least 800 °C. Solid bitumen reflectance also showed a sudden increase from a minimum of 1.50% outside the aureole to approximately 7.0% near the sill contact, a 5× increase as compared to an increase of 2× for vitrinite. This indicates that solid bitumen is a very sensitive indicator of temperature variation, more sensitive than vitrinite. Solid bitumen reflectance prior to the sill emplacement can only be inferred from the solid bitumen below the lower, younger sill because of poor control on solid bitumen in the interval just above the upper, older sill. Reflectance trends above and below the sills appear to be symmetrical despite the superimposition of the effects of one sill on the other. The metamorphic effects of the sill, as determined vertically by the reflectance trend, can be observed for a distance of up to seven times its thickness. The upper, older sill is approximately 45 m thick and the thermal aureole zone above it has a width of 330 m. The thickness of the aureole below the sill is difficult to establish because it has been obliterated by the effect of the lower, younger sill. The thickness of the lower sill is 75 m. An additional factor that influenced solid bitumen reflectance in this case may have been the thickness of the sill, which, in turn, affects the cooling time of the intrusive body. The granodiorite sills are approximately 45–75 m thick and the diabase sill is almost 120 m.

Springtails (Collembola) in the Subpolar Landscapes of the Northern Hemisphere

An overview of previously published and new information on the collembolan fauna and assemblage structure in the polar desert zone is presented. So far, 71 springtail species from 37 genera and 11 families have been reliably recorded within the zone. Eleven species are added to the previously known fauna of Franz Josef Land, and the very north of Novaya Zemlya has been surveyed for the first time. Even the much better known fauna of Bolshevik Island, Severnaya Zemlya is enriched by 3 species. The known species richness of springtails of Ellef Ringnes Island, Canadian Arctic Archipelago, is also increased from 8 to 13 species. Most genera except Folsomia and Hypogastrura include only 1, more rarely 2 species in each study region of the polar desert zone. Species with circumpolar distribution patterns comprise more than 60% of the total list, but only 10 species are common to all the three provinces; this obviously indicates a certain regional specificity. Besides, the faunas of different provinces (and regions within a province) vary markedly in the proportion of species with more southern distribution patterns. Nevertheless, the collembolan assemblages in all the three provinces of the polar desert zone are rather similar at the structural level, this being a direct consequence of the general depletion of the complexes against the background of high total abundance and less pronounced habitat specificity of the common species.

Extensive Early Cretaceous (Albian) methane seepage on Ellef Ringnes Island, Canadian High Arctic

Research Article| July 01, 2017 Extensive Early Cretaceous (Albian) methane seepage on Ellef Ringnes Island, Canadian High Arctic Krista Williscroft; Krista Williscroft 1Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada Search for other works by this author on: GSW Google Scholar Stephen E. Grasby; Stephen E. Grasby † 1Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada2Geological Survey of Canada, Natural Resources Canada, 3303 33rd Street NW, Calgary, Alberta T2L 2A7, Canada †Corresponding author: steve.grasby@canada.ca. Search for other works by this author on: GSW Google Scholar Benoit Beauchamp; Benoit Beauchamp 1Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada Search for other works by this author on: GSW Google Scholar Crispin T.S. Little; Crispin T.S. Little 3School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK Search for other works by this author on: GSW Google Scholar Keith Dewing; Keith Dewing 1Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada2Geological Survey of Canada, Natural Resources Canada, 3303 33rd Street NW, Calgary, Alberta T2L 2A7, Canada Search for other works by this author on: GSW Google Scholar Daniel Birgel; Daniel Birgel 4Institute of Geology, University of Hamburg, 20146 Hamburg, Germany Search for other works by this author on: GSW Google Scholar Terry Poulton; Terry Poulton 2Geological Survey of Canada, Natural Resources Canada, 3303 33rd Street NW, Calgary, Alberta T2L 2A7, Canada Search for other works by this author on: GSW Google Scholar Krzysztof Hryniewicz Krzysztof Hryniewicz 5Institute of Paleobiology, Polish Academy of Sciences, ul. Twarda 51/55, 00-818 Warszawa, Poland Search for other works by this author on: GSW Google Scholar GSA Bulletin (2017) 129 (7-8): 788–805. https://doi.org/10.1130/B31601.1 Article history received: 27 Jun 2016 rev-recd: 20 Dec 2016 accepted: 21 Feb 2017 first online: 06 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Krista Williscroft, Stephen E. Grasby, Benoit Beauchamp, Crispin T.S. Little, Keith Dewing, Daniel Birgel, Terry Poulton, Krzysztof Hryniewicz; Extensive Early Cretaceous (Albian) methane seepage on Ellef Ringnes Island, Canadian High Arctic. GSA Bulletin 2017;; 129 (7-8): 788–805. doi: https://doi.org/10.1130/B31601.1 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 During field mapping of Ellef Ringnes Island, Canadian Arctic Archipelago, 139 isolated Early Cretaceous methane seep deposits were found from 75 field sites. Stable isotopes of the carbonates have values of δ13C = –47‰ to –35‰ and δ18O = –4.0‰ to +0.7‰. Isoprenoids in organics from one of the seeps are significantly depleted in 13C, with the most negative δ13C value of –118‰ and –113‰ for 2,6,10,15,19-pentamethylicosane (PMI) and phytane/crocetane, respectively. These values indicate an origin through methane oxidation, consistent with biomarkers that are characteristic for anaerobic methanotrophic archaea within the seep deposits, accompanied by terminally branched fatty acids showing similar 13C values (–92‰) sourced from sulfate-reducing bacteria. The seep deposits contain a moderate-diversity macrofaunal assemblage comprising ammonites, bivalves, gastropods, scaphopods, “vestimentiferan” worm tubes, and brachiopods. The assemblage is dominated numerically by species that probably had chemosymbionts. The seep deposits formed in the subsurface within strong redox zones, in an otherwise normal marine setting, characterized by oxic waters at high paleolatitudes.While geographically widespread over an area of ∼10,000 km2, seep deposits on Ellef Ringnes Island occur in a narrow stratigraphic horizon, suggesting a large release of biogenic methane occurred over a brief period of time. This gas release was coincident with a transition from a cold to warm climate during the latest early Albian, and we hypothesize that this may have been related to gas hydrate release. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Lower Cretaceous cold snaps led to widespread glendonite occurrences in the Sverdrup Basin, Canadian High Arctic

Dramatic global climate change in the Early Cretaceous suggests that numerous boreal cool events perturbed otherwise warm conditions. Abundant glendonites in Valanginian and Aptian strata are thought to be key markers of cold conditions; however, their use as climate indicators has been questioned. Therefore, a detailed study of glendonites in the context of host-rock geochemistry was conducted on Cretaceous strata exposed on Ellef Ringnes Island, Sverdrup Basin, Canadian High Arctic, to elucidate paleoenvironment controls on periodic glendonite occurrence throughout the Early Cretaceous. Two prominent glendonite zones were identified in Valanginian and Aptian strata. Data for carbon stable isotopes show δ 13 C carb values of −29.5‰ to −10.5‰, consistent with a carbon source from organic matter within the surrounding shale. Trace metal data suggest deposition occurred under an overall oxidizing water column in a setting with higher than average phosphorus and highly degraded organic matter. There is no variation in the geochemical parameters of the mudstones with or without glendonites. Glendonite-bearing zones are coincident, however, with regional evidence for brief periods of colder climate conditions within the otherwise warm Early Cretaceous. We conclude that while the overall conditions for glendonite formation were prevalent throughout the Cretaceous, it was the brief cold periods that provided the final range of stability for their preservation in discrete zones of Valanginian and Aptian strata. These results support the model of an overall warm Early Cretaceous climate being punctuate by several “cold snaps” of as-yet uncertain origin.

U–Pb geochronology of bentonites from the Upper Cretaceous Kanguk Formation, Sverdrup Basin, Arctic Canada: constraints on sedimentation rates, biostratigraphic correlations and the late magmatic history of the High Arctic Large Igneous Province

AbstractU–Pb ages of zircon from bentonites within the upper Cretaceous Bastion Ridge and Kanguk formations, Sverdrup Basin, provide constraints on sedimentation rates, biostratigraphic correlations, timing of Oceanic Anoxic Event 2 (OAE2) in the High Arctic, and the late magmatic history of the High Arctic Large Igneous Province (HALIP). A late Cenomanian to early Turonian age for the base of the Kanguk Formation is confirmed that supports correlations of the global OAE2 in the High Arctic. Sedimentation rates varied from 19 m Ma−1between 93 and 91 Ma to 26 m Ma−1between 91 and 83 Ma at Axel Heiberg Island. At Ellef Ringnes Island, the lower Kanguk Formation records high rates of ~70 m Ma−1between 94 and 93 Ma, which decrease to rates comparable to those of the upper Axel Heiberg section. Differences in sedimentation rates may reflect differences in setting prior to the major transgression in the latest Cenomanian to early Turonian. The timing of Arctic occurrences of theScaphites nigricollensisandScaphites depressusammonite zones is shown to be broadly comparable to that of lower-latitude occurrences within the Western Interior Seaway. An eruption frequency of 0.5–2.5 Ma characterizes the late alkaline phase of HALIP magmatism. Volcanic bed thicknesses of 10–50 cm suggest ash transport distances of less than 1000 km. Long-lived volcanic centres, in the area of the Alpha Ridge, northern Ellesmere Island or northern Greenland, were the likely source of volcanic ash over a period of 10–15 Ma.

Characteristics of colored dissolved organic material in first year landfast sea ice and the underlying water column in the Canadian Arctic in the early spring

The absorption of solar energy by colored dissolved organic material (CDOM) in Arctic surface waters during the springtime is increasingly recognized as having profound impacts on seasonal retreat of ice from the Arctic Ocean. This study observed the production of CDOM within first year landfast sea ice, its contribution to light absorption within the water column and its photoreactivity, at a location near Ellef Ringnes Island in the Canadian Archipelago during the spring of 2011. CDOM was the optically dominant component of non-water absorption, increasing the energy absorption and heating potential in the top 8m by 30% over pure seawater. CDOM absorption within sea ice brine channels increased with solar-stimulated ice algae production. This ice algal mediated production of CDOM exceeded photooxidation rates, potentiating a net delivery of CDOM to the immediately underlying water column from brine channels in the ice. The rates of production and loss of CDOM in Arctic waters during the early spring quantified here will help constrain a major uncertainty in modeling light absorption by surface waters that contributes to sea ice loss in the Arctic.

Geological evolution and hydrocarbon potential of the salt-cored Hoodoo Dome, Sverdrup Basin, Arctic Canada

The evaporite-cored Hoodoo Dome on southern Ellef Ringnes Island, Sverdrup Basin, was examined to improve the understanding of its structural geological history in relation to hydrocarbon migration. Data from geological mapping, reflection seismic, thermal maturity and detrital apatite (U–Th)/He cooling ages are presented. Five stages of diapirism are interpreted from Jurassic to Recent times:1. 180 to 163 Ma (pre-Deer Bay Formation; development of a diapir with a circular map pattern).2. 163 to 133 Ma (Deer Bay to lower Isachsen formations; development of salt wings).3. 115 to 94 Ma (Christopher and Hassel formations; ongoing diapirism and development of an oval map pattern)4. 79 Ma (Kanguk Formation; reactivation of the central diapir).5. 42 Ma to 65 Ma (Eurekan Orogeny; tightening of the anticline).During phase1, the Hoodoo diapir was circular. During phase 2, salt wings formed along its margin. During phase 3, the Hoodoo Dome geometry evolved into a much larger, elongate, doubly plunging anticline. Phase 4 is inferred from thermochronology data as indicated by a cluster of cooling ages, but the extent of motion during that time is unknown. During Phase 5 the dome was tightened creating approximately 700 m of structural relief. Denudation since the end of the Eurekan Orogeny is estimated to be about 600 m.A one dimensional burial history model predicts hydrocarbon generation from Middle and Late Triassic source rocks between 140 and 66 Ma, with majority of hydrocarbon expulsion between 117 and 79 Ma. Hydrocarbon generation post-dates salt wing formation, so that this trap could host natural gas expelled from Triassic source rocks.

Cenomanian to Santonian radiolarian biostratigraphy, carbon isotope stratigraphy and paleoenvironments of the Sverdrup Basin, Ellef Ringnes Island, Nunavut, Canada

An upper Albian to Santonian sedimentary record on Ellef Ringnes Island, Canadian Arctic Archipelago, records variable paleoenvironmental conditions within the Cretaceous Polar Sea and Sverdrup Basin. The upper Albian to lower Cenomanian uppermost Christopher and Hassel formations represent a regressive system tract from offshore to shoreface/terrestrial paleoenvironments. The upper Cenomanian to Santonian shales of the Kanguk Formation signify a distal offshore basin setting controlled by increased subsidence and high global sea levels. Siliceous pelagic faunas and floras dominate the basin and herein, three informal radiolarian partial range zones are proposed for the Polar Sea. Alternating diversity and abundance patterns are interpreted as a response to sea-level controlled productivity systems. Transgressive phases correspond to low diversity shallow dwelling radiolarian taxa with an expanded oxygen minimum zone (OMZ); regressive phases are coupled with radiolarian radiations of deeper dwelling species and a depressed OMZ. The upper Cenomanian to Turonian was marked by increased preservation of marine-type organic matter and organic carbon isotope excursions indicate the presence of the Oceanic Anoxic Event 2 (OAE 2) at the base of the Kanguk Formation. Rock Eval data suggest that an increasing terrestrial influence prevailed during the Coniacian to Campanian time covering the OAE 3. Benthic environments are dominated by anoxic conditions, as suggested by the near lack of benthic foraminifera and extensive intervals of fine platy shale lacking bioturbation. Only the upper Coniacian records a return to dysoxic benthic conditions. Radiolarian faunal comparisons to more southern localities suggest migration routes from the east through a narrow North Atlantic pathway and from the Pacific through the Alaskan–Asian Pathway.

Sedimentology and stratigraphy of the Lower Cretaceous Isachsen Formation: Ellef Ringnes Island, Sverdrup Basin, Canadian Arctic Archipelago

The Lower Cretaceous Isachsen Formation is a widespread, siliciclastic succession up to 1.4 km thick that records the northwestward progradation of fluvio-deltaic environments into the Sverdrup Basin in the Canadian Arctic. Although the Isachsen Formation is a prominent unit with proven oil and gas reserves, detailed outcrop descriptions of its sedimentology and stratigraphy, and correlation of these features to subsurface data are rare. We examined outcrop exposures of the Isachsen Formation on Ellef Ringnes Island in the province of Nunavut in the Canadian Arctic in order to document and interpret the sedimentology and stratigraphy of this unit in the central portion of the Sverdrup Basin. Interpretations are based on observations from over 5000 m of measured stratigraphic sections, local mapping of facies contacts, palynology, and sandstone petrography. Deposits of the Isachsen Formation on Ellef Ringnes Island can be divided into six broadly-defined facies associations that record deposition in braided-fluvial, meandering-fluvial, floodplain, tidally-influenced fluvial, shoreface, and offshore environments. Sandstones within the Isachsen Formation are typically quartzose, commonly with compositions of >90% well-rounded, monocrystalline quartz. Although the sedimentary details between outcrop locations vary, a generalized stratigraphic trend is present within the Isachsen Formation. Where exposed, the base of the unit consists of marginal marine sandstones abruptly overlain by braided stream deposits, which grade into mudstone-rich, meandering-fluvial and floodplain deposits. These nonmarine deposits are overlain by a thin marine mudstone (Rondon Member), which is in turn overlain by marginal marine sandstone and fluvial deposits. The uppermost portion of the Isachsen Formation records a transgression and is overlain by marine mudstones of the Christopher Formation. The stratigraphic succession of the Isachsen Formation in outcrops correlates to data from nearby hydrocarbon exploration wells. Stratigraphically, the Isachsen Formation on Ellef Ringnes Island represents a regressive–transgressive sequence, but contains within it two higher-order regressive–transgressive sequences, which is consistent with observations from elsewhere in the Sverdrup Basin. The detailed descriptions of facies within the Isachsen Formation on Ellef Ringnes Island and their correlation to subsurface data can be extrapolated to other parts of the Sverdrup Basin where data are lacking.

Correlating middle Cretaceous palynological records from the Canadian High Arctic based on a section from the Sverdrup Basin and samples from the Eclipse Trough

Quantitative palynological analyses undertaken on the middle Cretaceous Hassel Formation of the Sverdrup Basin and reputedly equivalent rocks from the Eclipse Trough, about 850 km east, provide convincing evidence that they are coeval and of Late Albian–Cenomanian age. We base this conclusion on statistical definition of two palynomorph populations that occur in both spot samples from the Eclipse Trough and in samples from a measured section at Hoodoo Dome, Ellef Ringnes Island in the central Sverdrup Basin, which demonstrate a broad correlation to previously reported palynofloras from North America. By applying ordination techniques, we demonstrate that the range of variability of palynomorph composition of samples from the reputed Hassel Formation in the Eclipse Trough are within the range of variability defined for samples from the Hassel Formation, Hoodoo Dome. Comparable proportions of dicotyledonous angiosperm pollen characterize samples from both localities, but diversity and relative abundance are lower in both of the Canadian Arctic deposits than in more southern Middle and Late Albian–Cenomanian-aged rocks of North America. To explain this, we propose that restricted angiosperm diversity and continued dominance of gymnosperms and ferns into the Cenomanian in the Canadian Arctic reflect relatively cool continental climate conditions or barriers to migration, such as the Western Interior Seaway.

Vegetation of zonal patterned‐ground ecosystems along the North America Arctic bioclimate gradient

AbstractQuestion: How do interactions between the physical environment and biotic properties of vegetation influence the formation of small patterned‐ground features along the Arctic bioclimate gradient?Location: At 68° to 78°N: six locations along the Dalton Highway in arctic Alaska and three in Canada (Banks Island, Prince Patrick Island and Ellef Ringnes Island).Methods: We analysed floristic and structural vegetation, biomass and abiotic data (soil chemical and physical parameters, the n‐factor [a soil thermal index] and spectral information [NDVI, LAI]) on 147 microhabitat relevés of zonal‐patterned‐ground features. Using mapping, table analysis (JUICE) and ordination techniques (NMDS).Results: Table analysis using JUICE and the phi‐coefficient to identify diagnostic species revealed clear groups of diagnostic plant taxa in four of the five zonal vegetation complexes. Plant communities and zonal complexes were generally well separated in the NMDS ordination. The Alaska and Canada communities were spatially separated in the ordination because of different glacial histories and location in separate floristic provinces, but there was no single controlling environmental gradient. Vegetation structure, particularly that of bryophytes and total biomass, strongly affected thermal properties of the soils. Patterned‐ground complexes with the largest thermal differential between the patterned‐ground features and the surrounding vegetation exhibited the clearest patterned‐ground morphologies.Conclusions: Characterizing the composition and structure of small‐scale plant communities growing on distinctive microhabitats within patterned‐ground complexes was necessary to understand the biological and physical controls of vegetation on patterned‐ground morphology. Coarser‐scale vegetation units, referred to here as ‘zonal patterned‐ground vegetation complexes’ (groups of patterned‐ground plant communities within zonal landscapes), were useful for landscape and regional‐level comparisons and for extrapolation of information collected at plot scales to larger regions. Vegetation maps of the representative landscapes in each subzone were needed for extrapolation. Different growth characteristics of plants growing in northern and southern parts of the gradient have an important effect in stabilizing highly frost‐active soils. A conceptual diagram summarizes the interactions between vegetation and patterned‐ground morphology along the Arctic climate gradient.

Timing and mechanisms controlling evaporite diapirism on Ellef Ringnes Island, Canadian Arctic Archipelago

ABSTRACTThe Permo‐Carboniferous to Eocene Sverdrup Basin in Canada's Arctic Archipelago is strongly influenced by evaporite diapirism. However, salt structures within the basin have not been extensively investigated recently due to their remote location. This study includes the interpretation of legacy seismic reflection and borehole data to characterize the geometry of selected evaporite domes, and 1D backstripping of wells to investigate tectonic and sedimentary influences on diapirism. Extensional rift‐structures appear to have played a significant role in the formation of evaporite domes by triggering and directing salt movement. Diapirism was initiated by at least the Middle Triassic and continued to develop during the Mesozoic. Differential loading of salt on opposing east–west dome margins led to their present day asymmetric geometries. Diapir growth rates in the Mesozoic were closely linked to the rate of sedimentation and influenced by regional tectonism.

Unusual assemblages of Late Cretaceous silicoflagellates from the Canadian Archipelago

Devon and Ellef Ringnes islands in the Canadian Arctic Archipelago contain well-preserved Santonian through early Campanian silicoflagellates. These occur in three unusual assemblages, which comprise three biostratigraphic zones. The oldest, the Vallacerta tumidula Partial Range Zone of Santonian age, contains an extremely variable microflora that includes species of the poorly-known genus Variramus, two new species of Cornua, and a new genus Umpiocha. The Schulzyocha ruppelii Range Zone of early Campanian age includes several species of the new genus Schulzyocha, reflecting quadrate silicoflagellate skeletal morphologies that lack a basal structure. The youngest assemblage includes the poorly-known species Cornua trifurcata, the nominative taxon of the C. trifurcata Partial Range Zone (proposed by McCartney et al., in press c; emended herein), which allows a correlation with a silicoflagellate-bearing sequence from the Horton River area, Northwest Territories of Canada. This report presents information on 24 silicoflagellate taxa, proposes 2 new genera, Schulzyocha and Umpiocha, and describes 13 new species and 1 new combination. All of these new taxa disappear by the top of the Campanian Cornua trifurcata Partial Range Zone. These assemblages reveal a new history of silicoflagellate evolution prior to the late Campanian, the period from which most of our prior knowledge about Cretaceous silicoflagellates was derived. The assemblages show progressive change from skeletons with highly variable morphologies to more stable silicoflagellate skeletal geometry. Two important Corbisema species, C. apiculata and C. archangelskiana, appear to be derived from separate lines within Cornua in the latest Santonian and early Campanian. The important Cretaceous genus Lyramula makes its first appearance at the beginning of the Campanian.

A 10 400-Year-Old Bowhead Whale (&lt;i&gt;Balaena mysticetus&lt;/i&gt;) Skull from Ellef Ringnes Island, Nunavut: Implications for Sea-Ice Conditions in High Arctic Canada at the End of the Last Glaciation

Variations in the distribution and radiocarbon ages of postglacial bowhead whale (Balaena mysticetus) remains throughout the Canadian Arctic Archipelago indicate that the range of this whale expanded and contracted several times during the Holocene. Since the annual bowhead migration reflects the preference of this species for an ice-edge habitat, fossil bowheads have been used to infer that significant variations in summer sea-ice extent occurred throughout the archipelago during the last 10.5 thousand years. Previous studies have demonstrated that climatic amelioration, concomitant with enhanced meltwater flux from the retreating Laurentide Ice Sheet, cleared sea ice from the inter-island channels of the central archipelago, enabling early Holocene bowhead whales to extend beyond the range of contemporary populations. A 10.4 ka BP bowhead whale skull was discovered on Ellef Ringnes Island in the northern Canadian Arctic Archipelago, 700 km north of its previously reported early Holocene range. Consequently, sea ice along the polar margin of the Canadian Arctic Archipelago is inferred to have been less extensive than previously recognized. Both biological evidence and glaciological evidence suggest that this reduction in sea-ice extent was the result of climate forcing, amplified by meltwater-driven outflows from the rapidly retreating marine-based sector of the Innuitian Ice Sheet. Following a reduction of these outflows at ~9 ka BP, sea-ice conditions worsened, despite ongoing climatic amelioration, preventing additional bowhead whale incursions until ~4 ka BP.

Почвенные неподвижные зеленые микроводоросли (Chlorophyta) острова Еллеф Рингнес (Канадский арктический архипелаг)

The results of investigation of the taxonomic diversity of the nonmotile unicellular and colonial green algae in the soils of Ellef Ringnes Island (Canadian Arctic Archipelago) are expounded. 49 genera and 88 species of algae belonging to the classes Chlamydophyceae and Chlorophyceae (Chlorophyta) are recorded. 64 species and 23 genera are new for the area of polar deserts.

Morphodynamics of Cold High Latitude Semiarid Regions: The Example of Ellef Ringnes Island, Nunavut*

In this paper we use the example of Ellef Ringnes Island, Nunavut, to examine active geomorphic processes in a high latitude semiarid region. The spectacular landscape of Ellef Ringnes Island is principally the result of fluvial erosion controlled by geological structure. The nival regime concentrates flow in a brief late-spring period which provides strong erosive capabilities for rivers in spite of low annual precipitation. Other processes related to the cold environment produce a variety of minor landforms such as patterned ground, mud flows associated with ground ice, and solifluction lobes.

The Indefatigable Mary R. Dawson: Arctic Pioneer

Abstract Between 1973 and 2002, Mary Dawson and team spent 11 field seasons searching for vertebrate fossils on Ellesmere, Axel Heiberg, Devon, Ellef Ringnes, Bylot, and Banks Islands in Canada's Arctic Archipelago. Their pioneering efforts resulted in one of the greatest discoveries in vertebrate paleontology of the twentieth century—the first, and best, record of Paleogene terrestrial vertebrates from within the Arctic Circle. Here we provide a history of the field research and discoveries by Dawson and collaborators in the Canadian High Arctic. Discovery of Eocene vertebrate faunas in the Eureka Sound Group on Ellesmere and Axel Heiberg Islands supports the former existence of a high-latitude land connection between Europe and North America, provides insight into the origin of certain mammalian taxa such as microparamyine rodents, and yields evidence for a warm, temperate High Arctic climate at that time. Moving up in the section, Dawson's discoveries in Haughton Astrobleme on Devon Island include the ...