Review of Greenland Avtivities 2001 - Geus

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53° 51° Inland Ice Greenland 72° Upernavik • Summit • Svartenhuk Halvø Nuugaatsiaq Nuuk • 500 km Illorsuit Palaeogene volcanic rocks 71° Ukkusissat Cretaceous sandstones and shales Niaqornat Qaarsut Precambrian basement Areas where landslides may generate tsunamis Nuussuaq Uummannaq Areas with high risk of landslides Fig. 2. Geological map of the Nuussuaq Basin with the landslideprone areas indicated. Frame shows location of Fig. 3, a detailed map of the Paatuut area. 70° Nuusap Qaqqarsua Disko Asuk Qullissat Ataata Kuua Fig. 3 Vaigat Paatuut Saqqaq Ujarasussuk Qeqertaq Sermersuaq Kangerluk Qeqertarsuaq Ilulissat 69° Disko Bugt 50 km Aasiaat Qasigiannguit 55° 51° 74
Landslides may move at different speeds, and slowly moving slides or debris flows are not considered dangerous. To initiate a tsunami the landslide must almost instantly displace huge volumes of water, and the likelihood of such an event increases with the steepness of the coast. The risk of tsunamis following landslides is consequently particularly high along the steep south coast of Nuussuaq where erosion is rapid and large volumes of debris accumulate at high altitudes (Fig. 2). Furthermore, tsunamis generated along the south coast of Nuussuaq are confined by the narrow Vaigat strait and are reflected from the opposite coast. Rock falls and landslides in the Disko–Nuussuaq area Old slide areas are recognisable from their geomorphological expression, and sometimes also by brickred colours produced by self-combustion in slipped carbon-rich shales. Such burnt lithologies are prominent at Paatuut and Ataata Kuua (Fig. 3) and indicate a high frequency of slides. Many slides are indicated on the Survey’s 1:100 000 geological maps of the region. Most of these slides must be less than 10 000 years old, as they post-date the last glaciation. In the period 10 000–3000 B.P. relative sea level was falling in the Disko Bugt area, and marine terraces as well as raised beaches were formed. Since 2800 B.P. sea level has been rising (Long et al. 1999). Along that part of the south coast of Nuussuaq where landslides are frequent, marine terraces are generally not seen; this indicates that the landslides present are probably younger than 3000 B.P. The Paatuut area is characterised by large landslides (Fig. 3). Between Paatuut and Ataata Kuua in particular, large lobes of rock debris superpose the glacial morphological surface. Huge solitary blocks of volcanic rocks on the slopes facing Vaigat are evidence of occasional rock falls, some of which may have generated tsunamis. The first published account of a landslide in Greenland is that of Steenstrup (1900), who recorded an event that occurred in 1870 near Ujarasussuk on the north coast of Disko. A mudflow with large floating blocks of basalt built a lobe into the sea and hindered passage on foot along the coast. This landslide does not appear to have caused a tsunami or any damage to houses or inhabitants in Ujarasussuk. Landslides are a recurring phenomenon near Niaqornat in northern Nuussuaq. In most cases spontaneous combustion in shales is reported about one year after the slide (Rosenkrantz 1967; Henderson 1969). The village Niaqornat was hit by falling rocks in 1978, and west of the village the risk of future slides is high (Pulvertaft 1979). 70°21′ Ataata Kuua Landslide 15.12.1952 Tupaasat 70°18′ Landslide Escarpment at head of slide Basalt scree below steep basalt cliff Fig. 3. Map of part of the south coast of Nuussuaq showing the many large and small landslides in the area, including the new slide at Paatuut. The contours are drawn from vertical aerial photographs at scale 1:150 000 taken in 1985 and, for the Paatuut slide, from oblique photographs taken in July 2001. 70°15′ Alluvial fan Undifferentiated Quaternary cover Palaeogene basalt formations Atane Formation, sandstones interlayered with shales and coal seams Atane Formation with Quaternary cover 5 km Contour interval 100 m 53° Vaigat Landslide Paatuut 21.11.2000 52°45′ 75
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GEOLOGY OF GREENLAND SURVEY BULLETI
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Geology of Greenland Survey Bulleti
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Contents Numbers of articles corres
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■ ■ ■ ■ ■ ■ ■ ■ ■
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Canada Pituffik O 1 Thule Air Base
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Publications A complete list of geo
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Canada Greenland Greenland Inland I
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northern Nagssugtoqidian orogen (SN
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western to the north-eastern corner
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group consists of conjugate sets of
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y pure shear. Coincidence of the or
Page 26 and 27: The Precambrian supracrustal rocks
Page 28 and 29: 68°25′ 52° 68°25′ BIF 0 3 km
Page 30 and 31: Fig. 4. Dolomitic marble in the sou
Page 32 and 33: Bugt (Fig. 1; Henderson 1969). The
Page 34 and 35: Keto, L. 1962: Aerial prospecting b
Page 36 and 37: ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲
Page 38 and 39: increases towards the south. We obs
Page 40 and 41: Kalsbeek, F. & Taylor, P.N. 1999: R
Page 42 and 43: Canada Nuussuaq 0 50 km PROTEROZOIC
Page 44 and 45: deposit. Descriptions of the differ
Page 46 and 47: Pegmatites The gneisses throughout
Page 48 and 49: tacts with quartzo-feldspathic coun
Page 50 and 51: Geological correlation of magnetic
Page 52 and 53: Fig. 2. The hand-held magnetic susc
Page 54 and 55: Susceptibility distribution (%) Sus
Page 56 and 57: have a reducing effect, which hinde
Page 58 and 59: ancy between the susceptibility val
Page 60 and 61: 67° Sisimiut • 53° 52° 51° 50
Page 62 and 63: Table 1. Range of Nb concentrations
Page 64 and 65: chemical composition - may indicate
Page 66 and 67: Concentration/C1 chondrite 100.00 1
Page 68 and 69: Menzies, M.A. & Hawkesworth, C.J. (
Page 70 and 71: 72°30´ Aeromag 2001 50 km Upernav
Page 72 and 73: 56° 54° 52° 72° 72° nT 71°30
Page 74 and 75: Conclusions The aeromagnetic survey
Page 78 and 79: On the south coast of Nuussuaq, wes
Page 80 and 81: Fig. 5. Blocks and boulders in the
Page 82 and 83: 2000 SW NE 1500 Surface trace 1985
Page 84 and 85: 1979). Along other sections of the
Page 86 and 87: Petroleum geological activities in
Page 88 and 89: Seismic acquisition during summer 2
Page 90 and 91: Other petroleum geological work Alt
Page 92 and 93: A multidisciplinary study of the Pa
Page 94 and 95: Seismic interpretation The grid of
Page 96 and 97: Middle Eocene Lower Eocene Upper Pa
Page 98 and 99: Chalmers, J.A., Dahl, J.T., Bate, K
Page 100 and 101: 95-06 ▲ ▲ 58° 95-12 95-10 56°
Page 102 and 103: 70° 71° 60° 2000 2000 2400 400 1
Page 104 and 105: Storey, M., Duncan, R.A., Pedersen,
Page 106 and 107: 24° 100 km 30° 27° 21 ° Jameson
Page 108 and 109: Oligocene Krabbedalen Fm Eocene Bop
Page 110 and 111: grading. Bivalve shell material is
Page 112 and 113: References Birkenmajer, K. 1972: Re
Page 114 and 115: B A 72° Palaeogene basalts Gl 50 k
Page 116 and 117: a b c d e f g h 20 µm i j k l Fig.
Page 118 and 119: offshore South-East Greenland, onsh
Page 120 and 121: ▲ Albert Heim Bjerge Wordie Gletc
Page 122 and 123: T D A CW NS placed the lowermost c.
Page 124 and 125: is abundant and highly diverse, and
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The Heimbjerge Formation comprises
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Late Permian carbonate concretions
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m 25 20 15 B3 L2 B2 Fig. 3. Simplif
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(2001), who pointed out the restric
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Piasecki, S. 1984: Preliminary paly
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66° 68° • • • • • • 7
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absent at Tikeraussaq where a postu
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72° 70° 68° 66° Sample locality
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Table 2. Summary of selected elemen
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Concluding remarks Observations dur
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Lake-catchment interactions with cl
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lakes. As in earlier reports (e.g.
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Discussion Global climate models pr
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Glaciological investigations on ice
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Fig. 2. The new one-mast design of
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A B N 20 km 1993 1995 Fig. 5. Satel
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Krabill, W., Frederick, E., Manizad
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2001/47: Calibration of stream sedi
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Hanghøj, K., Kelemen, P., Bernstei
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Danmarks og Grønlands Geologiske U
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GEOLOGY OF GREENLAND SURVEY BULLETI
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