scholarly journals Submarine landforms reveal varying rates and styles of deglaciation in North-West Greenland fjords

2018 ◽  
Vol 402 ◽  
pp. 60-80 ◽  
Author(s):  
C.L. Batchelor ◽  
J.A. Dowdeswell ◽  
E. Rignot
Author(s):  
Bjørn Thomassen ◽  
Johannes Kyed ◽  
Agnete Steenfelt ◽  
Tapani Tukiainen

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.


Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen

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.


Author(s):  
Bjørn Thomassen ◽  
Peter R. Dawes ◽  
Agnete Steenfelt ◽  
Johan Ditlev Krebs

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., Dawes, P. R., Steenfelt, A., & Krebs, J. D. (2002). Qaanaaq 2001: mineral exploration reconnaissance in North-West Greenland. Geology of Greenland Survey Bulletin, 191, 133-143. https://doi.org/10.34194/ggub.v191.5141 _______________ Project Qaanaaq 2001, involving one season’s field work, was set up to investigate the mineral occurrences and potential of North-West Greenland between Olrik Fjord and Kap Alexander (77°10´N – 78°10´N; Fig. 1). Organised by the Geological Survey of Denmark and Greenland (GEUS) and the Bureau of Minerals and Petroleum (BMP), Government of Greenland, the project is mainly funded by the latter and has the overall goal of attracting the interest of the mining industry to the region. The investigated region – herein referred to as the Qaanaaq region – comprises 4300 km2 of ice-free land centred on Qaanaaq, the administrative capital of Qaanaap (Thule) municipality. Much of the region is characterised by a 500–800 m high plateau capped by local ice caps and intersected by fjords and glaciers. High dissected terrain occurs in Northumberland Ø and in the hinterland of Prudhoe Land where nunataks are common along the margin of the Inland Ice.


2014 ◽  
Vol 92 ◽  
pp. 292-309 ◽  
Author(s):  
J.A. Dowdeswell ◽  
K.A. Hogan ◽  
C. Ó Cofaigh ◽  
E.M.G. Fugelli ◽  
J. Evans ◽  
...  

1983 ◽  
Vol 115 ◽  
pp. 49-56
Author(s):  
B Chadwick ◽  
M.A Crewe ◽  
J.F.W Park

The programme of field investigations in the north of the Ivisartoq region begun in 1981 by Chadwick & Crewe (1982) was continued in 1982. Julia Park began mapping the Taserssuaq granodiorite, its host rocks and the Ataneq fault in the north-west. Dur team was joined by D. Bellur, Geological Survey of India, nominally as an assistant. In this report we present only summary notes of new findings relevant to the interpretation of the geometry and chronology of this segment of the Archaean crust in southern West Greenland. We use the established terminology for the Archaean rocks of the Godthåbsfjord region.


1972 ◽  
Vol 100 ◽  
pp. 1-132
Author(s):  
S Floris

Localities and deposits in north-west Nûgssuaq yielding fossil corals of the order Scleractinia are described. The age of the corals is Campanian?, Maastrichtian and Lower Paleocene (Danian), on the basis of other marine fossils. 22 species are considered; 7 are described as new and are indigenous, 2 are possibly North American forms, 3 are known from Europe, and 10 are identifiable only to generic level. The following genera and subgenera are represented: Haimesiastraea (Haimesiastraea), H. (Perupiastrea)?, Discotrochus?, Astrangia (Coenangia)?, Oculina, Caryophyllia, Trochocyathus, Paracyathus, Stephanocyathus (Stephanocyathus), Desmophyllum?, Lophelia?, Parasmilia, Flabellum, Balanophyllia, and Dendrophyllia . In addition, two new genera are described: Kangiliacyathus and Faksephyllia . Certain Danian corals from Scandinavia are also revised. In a survey of habitats, the lithology of the corallocalities is considered together with bathymetric and thermal ranges known for scleractinian genera and species from other parts of the world. Depth and temperature of the Campanian and Maastrichtian seas in Greenland cannot be estimated with any accuracy. The Lower and Upper Danian seas were generally rather shallow. There is little evidence on which to judge the Danian climate. Two species were perhaps hermatypic (no reef structures have been found). The remaining scleractinians are presumed to have been ahermatypic. A non-reef coral association has been found. Lower Danian rather sparsely populated polytypic coral thickets show signs of continual disturbance from water turbulence. The approximate depth of formation of these thickets appears to have been 80 m or shallower, which appears to be less than is usual for coral structures of this type. Some Lower Paleocene species provide conclusive evidence of a direct connection between the Danian seas of West Greenland and of Scandinavia.


2020 ◽  
Vol 14 (1) ◽  
pp. 261-286 ◽  
Author(s):  
Kelly A. Hogan ◽  
Martin Jakobsson ◽  
Larry Mayer ◽  
Brendan T. Reilly ◽  
Anne E. Jennings ◽  
...  

Abstract. Petermann Fjord is a deep (>1000 m) fjord that incises the coastline of north-west Greenland and was carved by an expanded Petermann Glacier, one of the six largest outlet glaciers draining the modern Greenland Ice Sheet (GrIS). Between 5 and 70 m of unconsolidated glacigenic material infills in the fjord and adjacent Nares Strait, deposited as the Petermann and Nares Strait ice streams retreated through the area after the Last Glacial Maximum. We have investigated the deglacial deposits using seismic stratigraphic techniques and have correlated our results with high-resolution bathymetric data and core lithofacies. We identify six seismo-acoustic facies in more than 3500 line kilometres of sub-bottom and seismic-reflection profiles throughout the fjord, Hall Basin and Kennedy Channel. Seismo-acoustic facies relate to bedrock or till surfaces (Facies I), subglacial deposition (Facies II), deposition from meltwater plumes and icebergs in quiescent glacimarine conditions (Facies III, IV), deposition at grounded ice margins during stillstands in retreat (grounding-zone wedges; Facies V) and the redeposition of material downslope (Facies IV). These sediment units represent the total volume of glacial sediment delivered to the mapped marine environment during retreat. We calculate a glacial sediment flux for the former Petermann ice stream as 1080–1420 m3 a−1 per metre of ice stream width and an average deglacial erosion rate for the basin of 0.29–0.34 mm a−1. Our deglacial erosion rates are consistent with results from Antarctic Peninsula fjord systems but are several times lower than values for other modern GrIS catchments. This difference is attributed to fact that large volumes of surface water do not access the bed in the Petermann system, and we conclude that glacial erosion is limited to areas overridden by streaming ice in this large outlet glacier setting. Erosion rates are also presented for two phases of ice retreat and confirm that there is significant variation in rates over a glacial–deglacial transition. Our new glacial sediment fluxes and erosion rates show that the Petermann ice stream was approximately as efficient as the palaeo-Jakobshavn Isbræ at eroding, transporting and delivering sediment to its margin during early deglaciation.


Polar Record ◽  
1979 ◽  
Vol 19 (122) ◽  
pp. 489-491
Author(s):  
Wally Herbert

The object of the British North-Polar Expedition 1977–79 was for Allan Gill and myself to make the first circumnavigation of Greenland by dog sledge and umiak, beginning and ending at Thule in north-west Greenland (Fig 1). This 13 000 km journey estimated to take 16 months, was, I felt, one of the most interesting routes that a polar traveller could take; around the Greenland coast there is a greater variety of climate, scenery and physical obstacles than is likely to be encountered along a coastline of comparable length anywhere else in the world. I was convinced that as a literary and filming project this was an expedition that would justify not only the financial outlay, but also the good faith of all of those who had supported the project against the criticism that no polar journey is worthwhile unless it has a well conducted and acceptable scientific programme.


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