scholarly journals New thelodont (Agnatha) and possible chondrichthyan (Gnathostomata) taxa established in the Silurian and Lower Devonian of the Canadian Arctic Archipelago

2002 ◽  
Vol 51 (2) ◽  
pp. 88
Author(s):  
T Märss ◽  
R Thorsteinsson ◽  
M V Wilson
Keyword(s):  
Lower Devonian ◽  
Canadian Arctic ◽  
Canadian Arctic Archipelago

A Lower Devonian ammonoid, Mimagoniatites nearcticus n. sp., from the Canadian Arctic

1987 ◽  
Vol 61 (5) ◽  
pp. 974-981 ◽  
Author(s):  
Eric C. Prosh
Keyword(s):  
Lower Devonian ◽  
Canadian Arctic ◽  
Canadian Arctic Archipelago ◽  
High Degree

A newly discovered ammonoid, Mimagoniatites nearcticus n. sp., is described from upper Zlichovian–lower Dalejan (Lower Devonian) strata in the Canadian Arctic Archipelago. This species is distinguished primarily by its extremely narrow profile and high degree of whorl involution. It is the most gracile species so far known in the genus, and displays possible kinship to Parentites praecursor Bogoslovsky. This record constitutes the first definite occurrence of a Lower Devonian ammonoid from the Canadian Arctic Archipelago.

The Early Devonian (Pragian) zosterophyll Bathurstia denticulata Hueber

2000 ◽  
Vol 78 (2) ◽  
pp. 193-207 ◽  
Author(s):  
Michele E Kotyk ◽  
James F Basinger
Keyword(s):  
Phylogenetic Relationships ◽  
Lower Devonian ◽  
Canadian Arctic ◽  
Land Plants ◽  
Canadian Arctic Archipelago ◽  
Large Collection ◽  
Early Devonian ◽  
Northern Canada ◽  
Early Land

Approximately 86 specimens of Bathurstia denticulata Hueber were collected from upper Bathurst Island and lower Stuart Bay beds of Bathurst Island, Canadian Arctic Archipelago. Bathurstia was a component of a zosterophyll-dominated flora of Pragian age (Lower Devonian) that existed at low paleolatitudes in northern Canada. The large collection of well-preserved materials permits reconstruction of the plant as a robust scrambler of about 30 cm in height. Stems bear short, shelf-like emergences in two rows, and branch isotomously, although sparsely. Rooting organs, representing some of the oldest known for land plants, arise from the main aerial axes, although they are also associated with small, subordinate shoots interpreted as plantlets. Numerous specimens are fertile, with sporangia borne in dense terminal spikes. Spikes include two rows of overlapping, discoid sporangia. Isospores are round and featureless, and assignable to the genus Calamospora. While Bathurstia apparently originated from among the isotomously branching bilaterally symmetrical zosterophylls, the phylogenetic relationships of Bathurstia to known taxa is unclear, although some resemblance to Serrulacaulis, Barinophytaceae, and the Gosslingiaceae can be documented. Bathurstia denticulata is now one of the best known of early land plants, and contributes significantly to our understanding of zosterophylls and their role in Early Devonian vegetation.Key words: Bathurstia, zosterophyll, Devonian, Canada, Arctic, evolution.

scholarly journals Regional variability of acidification in the Arctic: a sea of contrasts

2014 ◽  
Vol 11 (2) ◽  
pp. 293-308 ◽  
Author(s):  
E. E. Popova ◽  
A. Yool ◽  
Y. Aksenov ◽  
A. C. Coward ◽  
T. R. Anderson
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Arctic Ocean ◽  
Canadian Arctic ◽  
Atmospheric Co2 ◽  
The Arctic ◽  
Canadian Arctic Archipelago ◽  
Regional Variability ◽  
The Arctic Ocean ◽  
The Impact

Abstract. The Arctic Ocean is a region that is particularly vulnerable to the impact of ocean acidification driven by rising atmospheric CO2, with potentially negative consequences for calcifying organisms such as coccolithophorids and foraminiferans. In this study, we use an ocean-only general circulation model, with embedded biogeochemistry and a comprehensive description of the ocean carbon cycle, to study the response of pH and saturation states of calcite and aragonite to rising atmospheric pCO2 and changing climate in the Arctic Ocean. Particular attention is paid to the strong regional variability within the Arctic, and, for comparison, simulation results are contrasted with those for the global ocean. Simulations were run to year 2099 using the RCP8.5 (an Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) scenario with the highest concentrations of atmospheric CO2). The separate impacts of the direct increase in atmospheric CO2 and indirect effects via impact of climate change (changing temperature, stratification, primary production and freshwater fluxes) were examined by undertaking two simulations, one with the full system and the other in which atmospheric CO2 was prevented from increasing beyond its preindustrial level (year 1860). Results indicate that the impact of climate change, and spatial heterogeneity thereof, plays a strong role in the declines in pH and carbonate saturation (Ω) seen in the Arctic. The central Arctic, Canadian Arctic Archipelago and Baffin Bay show greatest rates of acidification and Ω decline as a result of melting sea ice. In contrast, areas affected by Atlantic inflow including the Greenland Sea and outer shelves of the Barents, Kara and Laptev seas, had minimal decreases in pH and Ω because diminishing ice cover led to greater vertical mixing and primary production. As a consequence, the projected onset of undersaturation in respect to aragonite is highly variable regionally within the Arctic, occurring during the decade of 2000–2010 in the Siberian shelves and Canadian Arctic Archipelago, but as late as the 2080s in the Barents and Norwegian seas. We conclude that, for future projections of acidification and carbonate saturation state in the Arctic, regional variability is significant and needs to be adequately resolved, with particular emphasis on reliable projections of the rates of retreat of the sea ice, which are a major source of uncertainty.

scholarly journals On the Thermal Regime of a High-Arctic Valley Glacier

1976 ◽  
Vol 16 (74) ◽  
pp. 119-133 ◽  
Author(s):  
Fritz Müller
Keyword(s):  
Thermal Regime ◽  
Energy Input ◽  
Canadian Arctic ◽  
High Arctic ◽  
Canadian Arctic Archipelago ◽  
Valley Glacier ◽  
Drilling Technique ◽  
Percolation Zone ◽  
Mean Annual Air Temperature ◽  
Upper Boundary

AbstractThe 10 m temperatures were measured over several years at 16 sites on the White Glacier (lat. 80° N.), Axel Heiberg Island, Canadian Arctic Archipelago. At three sites deep profiles were made using a new drilling technique, reaching a maximum depth of 280 m. Large differences in the 10 m temperatures between locations and from year to year were observed. The deviations of these temperatures from the almost isothermal mean annual air temperature over the glacier are discussed. The heating effect of the melt water in the lower percolation zone was found to be very important. A conceptual model is developed to assess the influence of these irregularities in the energy input at the upper boundary on the thermal regime of the entire glacier. So far a quantitative analysis has been made only for the relatively simple 30 m temperature profile measured on the tongue of the glacier.

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