Archean and Proterozoic mantle in West Greenland

2019 ◽  
Keyword(s):  
West Greenland

Streamlined bedrock terrain and fast ice flow, Jakobshavns Isbrae, West Greenland: implications for ice stream and ice sheet dynamics

Boreas ◽  
2005 ◽  
Vol 34 (1) ◽  
pp. 25-42 ◽  
Author(s):  
David H. Roberts ◽  
Antony J. Long
Keyword(s):  
Ice Sheet ◽  
Ice Flow ◽  
West Greenland ◽  
Ice Stream ◽  
Fast Ice ◽  
Ice Sheet Dynamics

Seasonal diving and foraging behaviour of Eastern Canada-West Greenland bowhead whales

2020 ◽  
Vol 643 ◽  
pp. 197-217 ◽  
Author(s):  
SME Fortune ◽  
SH Ferguson ◽  
AW Trites ◽  
B LeBlanc ◽  
V LeMay ◽  
...  
Keyword(s):  
Climate Change ◽  
Late Summer ◽  
Calanoid Copepods ◽  
Eastern Canada ◽  
West Greenland ◽  
Bowhead Whales ◽  
Seasonal Movement ◽  
Dive Behaviour ◽  
Calanus Glacialis ◽  
Canada West

Climate change may affect the foraging success of bowhead whales Balaena mysticetus by altering the diversity and abundance of zooplankton species available as food. However, assessing climate-induced impacts first requires documenting feeding conditions under current environmental conditions. We collected seasonal movement and dive-behaviour data from 25 Eastern Canada-West Greenland bowheads instrumented with time-depth telemetry tags and used state-space models to examine whale movements and dive behaviours. Zooplankton samples were also collected in Cumberland Sound (CS) to determine species composition and biomass. We found that CS was used seasonally by 14 of the 25 tagged whales. Area-restricted movement was the dominant behaviour in CS, suggesting that the tagged whales allocated considerable time to feeding. Prey sampling data suggested that bowheads were exploiting energy-rich Arctic copepods such as Calanus glacialis and C. hyperboreus during summer. Dive behaviour changed seasonally in CS. Most notably, probable feeding dives were substantially shallower during spring and summer compared to fall and winter. These seasonal changes in dive depths likely reflect changes in the vertical distribution of calanoid copepods, which are known to suspend development and overwinter at depth during fall and winter when availability of their phytoplankton prey is presumed to be lower. Overall, CS appears to be an important year-round foraging habitat for bowheads, but is particularly important during the late summer and fall. Whether CS will remain a reliable feeding area for bowhead whales under climate change is not yet known.

Subfossil insect remains (Chironomidae) and lake-water temperature inference in the Sisimiut–Kangerlussuaq region, southern West Greenland

2000 ◽  
pp. 78-82 ◽  
Author(s):  
Klaus Peter Brodersen ◽  
N. John Anderson
Keyword(s):  
Climate Variability ◽  
Water Temperature ◽  
Lake Water ◽  
Anthropogenic Impact ◽  
Biological Diversity ◽  
Biological Indicators ◽  
Lake Ecosystems ◽  
West Greenland ◽  
Physical Chemical ◽  
Temperature Inference

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Brodersen, K. P., & Anderson, N. J. (2000). Subfossil insect remains (Chironomidae) and lake-water temperature inference in the Sisimiut–Kangerlussuaq region, southern West Greenland. Geology of Greenland Survey Bulletin, 186, 78-82. https://doi.org/10.34194/ggub.v186.5219 _______________ Climate and water temperature have an important influence on the functioning of lake ecosystems. From limnological and palaeolimnological studies of lakes, information on biological diversity and climate variability in time and space can be gleaned from physical, chemical and biological indicators preserved in the lake sediments. The lakes in southern West Greenland are particularly useful for this purpose – they are numerous, diverse and have minimal anthropogenic impact (Anderson & Bennike 1997). Palaeolimnological data are fundamental for understanding the functioning and development of modern lakes and for understanding the causes of climatic change as well as the effect on lake biota.

Aeromagnetic survey in southern West Greenland: project Aeromag 1999

2000 ◽  
pp. 73-77 ◽  
Author(s):  
Thorkild M. Rasmussen ◽  
Jeroen A.M. Van Gool
Keyword(s):  
European Union ◽  
Measured Data ◽  
Geophysical Data ◽  
Geological Survey ◽  
Aeromagnetic Survey ◽  
Original Series ◽  
West Greenland ◽  
The Government ◽  
Airborne Geophysical Data ◽  
Surface Geology

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, T. M., & van Gool, J. A. (2000). Aeromagnetic survey in southern West Greenland: project Aeromag 1999. Geology of Greenland Survey Bulletin, 186, 73-77. https://doi.org/10.34194/ggub.v186.5218 _______________ The acquisition of public airborne geophysical data from Greenland that commenced in 1992 continued in 1999 with project Aeromag 1999, an aeromagnetic survey of part of southern West Greenland. This paper presents results of the aeromagnetic survey and discusses the correlation of the measured data with the previously mapped surface geology. The project was financed by the Government of Greenland and managed by the Geological Survey of Denmark and Greenland. Sander Geophysics Ltd., Ottawa, Canada, was selected in April 1999 as the contractor for the project through a European Union opentender procedure.

Petroleum geological activities in West Greenland in 1998

1999 ◽  
pp. 46-56
Author(s):  
Flemming G. Christiansen ◽  
Anders Boesen ◽  
Jørgen A. Bojesen-Koefoed ◽  
James A. Chalmers ◽  
Finn Dalhoff ◽  
...  
Keyword(s):  
Seismic Data ◽  
Working Group ◽  
Petroleum Exploration ◽  
Geological Survey ◽  
Original Series ◽  
West Greenland ◽  
Phillips Petroleum ◽  
Petroleum Resources ◽  
The Government ◽  
Year 2000

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Christiansen, F. G., Boesen, A., Bojesen-Koefoed, J. A., Chalmers, J. A., Dalhoff, F., Dam, G., Ferré Hjortkjær, B., Kristensen, L., Melchior Larsen, L., Marcussen, C., Mathiesen, A., Nøhr-Hansen, H., Pedersen, A. K., Pedersen, G. K., Pulvertaft, T. C. R., Skaarup, N., & Sønderholm, M. (1999). Petroleum geological activities in West Greenland in 1998. Geology of Greenland Survey Bulletin, 183, 46-56. https://doi.org/10.34194/ggub.v183.5204 _______________ In the last few years there has been renewed interest for petroleum exploration in West Greenland and licences have been granted to two groups of companies: the Fylla licence operated by Statoil was awarded late in 1996; the Sisimiut-West licence operated by Phillips Petroleum was awarded in the summer of 1998 (Fig. 1). The first offshore well for more than 20 years will be drilled in the year 2000 on one of the very spectacular structures within the Fylla area. To stimulate further petroleum exploration around Greenland – and in particular in West Greenland – a new licensing policy has been adopted. In July 1998, the administration of mineral and petroleum resources was transferred from the Danish Ministry of Environment and Energy to the Bureau of Minerals and Petroleum under the Government of Greenland in Nuuk. Shortly after this, the Greenlandic and Danish governments decided to develop a new exploration strategy. A working group consisting of members from the authorities (including the Geological Survey of Denmark and Greenland – GEUS) made recommendations on the best ways to stimulate exploration in the various regions on- and offshore Greenland. The strategy work included discussions with seismic companies because it was considered important that industry acquires additional seismic data in the seasons 1999 and 2000.

Upernavik 98: reconnaissance mineral exploration in North-West Greenland

1999 ◽  
pp. 39-45 ◽  
Author(s):  
Bjørn Thomassen ◽  
Johannes Kyed ◽  
Agnete Steenfelt ◽  
Tapani Tukiainen
Keyword(s):  
Mineral Exploration ◽  
Mining Industry ◽  
Field Work ◽  
Geological Survey ◽  
Original Series ◽  
West Greenland ◽  
North West ◽  
One Year

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Thomassen, B., Kyed, J., Steenfelt, A., & Tukiainen, T. (1999). Upernavik 98: reconnaissance mineral exploration in North-West Greenland. Geology of Greenland Survey Bulletin, 183, 39-45. https://doi.org/10.34194/ggub.v183.5203 _______________ The Upernavik 98 project is a one-year project aimed at the acquisition of information on mineral occurrences and potential in North-West Greenland between Upernavik and Kap Seddon, i.e. from 72°30′ to 75°30′N (Fig. 1A). A similar project, Karrat 97, was carried out in 1997 in the Uummannaq region 70°30′–72°30′N (Steenfelt et al. 1998a). Both are joint projects between the Geological Survey of Denmark and Greenland (GEUS) and the Bureau of Minerals and Petroleum (BMP), Government of Greenland, and wholly funded by the latter. The main purpose of the projects is to attract the interest of the mining industry. The field work comprised systematic drainage sampling, reconnaissance mineral exploration and spectroradiometric measurements of rock surfaces.

The Archaean Atâ intrusive complex (Atâ tonalite), north-east Disko Bugt, West Greenland

1999 ◽  
pp. 103-112
Author(s):  
Feiko Kalsbeek ◽  
Lilian Skjernaa
Keyword(s):  
Intrusive Complex ◽  
The South ◽  
Original Series ◽  
Early Proterozoic ◽  
West Greenland ◽  
North East ◽  
The North ◽  
Southern Border ◽  
Area North ◽  
Igneous Layering

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kalsbeek, F., & Skjernaa, L. (1999). The Archaean Atâ intrusive complex (Atâ tonalite), north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 103-112. https://doi.org/10.34194/ggub.v181.5118 _______________ The 2800 Ma Atâ intrusive complex (elsewhere referred to as ‘Atâ granite’ or ‘Atâ tonalite’), which occupies an area of c. 400 km2 in the area north-east of Disko Bugt, was emplaced into grey migmatitic gneisses and supracrustal rocks. At its southern border the Atâ complex is cut by younger granites. The complex is divided by a belt of supracrustal rocks into a western, mainly tonalitic part, and an eastern part consisting mainly of granodiorite and trondhjemite. The ‘eastern complex’ is a classical pluton. It is little deformed in its central part, displaying well-preserved igneous layering and local orbicular textures. Near its intrusive contact with the overlying supracrustal rocks the rocks become foliated, with foliation parallel to the contact. The Atâ intrusive complex has escaped much of the later Archaean and early Proterozoic deformation and metamorphism that characterises the gneisses to the north and to the south; it belongs to the best-preserved Archaean tonalite-trondhjemite-granodiorite intrusions in Greenland.

Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland

1999 ◽  
pp. 65-78
Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen
Keyword(s):  
Tectonic Setting ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Metavolcanic Rocks ◽  
Arc Setting ◽  
Area North ◽  
Back Arc

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.

Proterozoic thermal activity in the Archaean basement of the Disko Bugt region and eastern Nuussuaq, West Greenland: evidence from K-Ar and 40Ar-39Ar mineral age investigations

1999 ◽  
pp. 55-64
Author(s):  
Henrik Rasmussen ◽  
Paul Martin Holm
Keyword(s):  
Structural Development ◽  
Thermal Activity ◽  
Excess Argon ◽  
Original Series ◽  
West Greenland ◽  
Precambrian Rocks ◽  
North Eastern ◽  
The Matrix ◽  
Radiogenic Argon

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Holm, P. M. (1999). Proterozoic thermal activity in the Archaean basement of the Disko Bugt region and eastern Nuussuaq, West Greenland: evidence from K-Ar and 40Ar-39Ar mineral age investigations. Geology of Greenland Survey Bulletin, 181, 55-64. https://doi.org/10.34194/ggub.v181.5113 _______________ K-Ar and 40Ar-39Ar analyses of amphiboles from Archaean amphibolites and gneisses show that Proterozoic tectono-thermal activity has played an important role in the metamorphic and structural development of the Precambrian rocks around north-eastern Disko Bugt and in eastern Nuussuaq. Proterozoic thermal activity lead to resetting of the K-Ar ages of amphiboles in eastern Nuussuaq, resulting in ages of c. 1750 to 1925 Ma; in the Disko Bugt area the effects are seen in total or partial resetting with K-Ar ages scattering mostly between 2750 and 1870 Ma. Resetting is caused either by total diffusion of earlier accumulated radiogenic argon or by complete recrystallisation of the amphiboles. Archaean 40Ar-39Ar ages obtained from mafic xenoliths within the Atâ tonalite show that not all parts of the area suffered argon loss during Proterozoic reheating. Incorporation of significant proportions of excess argon in some amphiboles is seen from 40Ar-39Ar mineral age spectra obtained for samples from supracrustal rocks and from mafic xenoliths in the Atâ tonalite. Phlogopite phenocrysts from a lamproite stock yielded a K-Ar age of 1764 ± 24 Ma, identical to a previously determined K-Ar age of the matrix phlogopite. These ages probably date the emplacement of the lamproite, and mark the time after which no tectono-thermal events affected the area.

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