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Geological Survey of Denmark and Greenland Bulletin 19 ... - Geus

Geological Survey of Denmark and Greenland Bulletin 19 ... - Geus

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DGR<br />

<strong>Geological</strong> setting<br />

As a result <strong>of</strong> the opening <strong>of</strong> the Labrador Sea in Late<br />

Mesozoic to Early Cenozoic times, a complex <strong>of</strong> linked<br />

rift basins stretching from the Labrador Sea to northern<br />

Baffin Bay developed along West Greenl<strong>and</strong> (Fig. 1;<br />

Chalmers & Pulvertaft 2001).<br />

Two main episodes <strong>of</strong> regional rifting <strong>and</strong> basin development<br />

during this time have been documented in the<br />

area: an episode <strong>of</strong> Early Cretaceous rifting, <strong>and</strong> a Late<br />

Cretaceous – Early Paleocene rift episode prior to the start<br />

<strong>of</strong> sea-floor spreading in mid-Paleocene time (Dam &<br />

Sønderholm <strong>19</strong>98; Dam et al. 2000; Chalmers &<br />

Pulvertaft 2001; Dam 2002; Sørensen 2006).<br />

The most extensive outcrops <strong>of</strong> Mesozoic–Palaeogene<br />

rocks in the entire Labrador Sea – Davis Strait – Baffin<br />

Bay region are those <strong>of</strong> the Nuussuaq Basin in the Disko<br />

– Nuussuaq – Svartenhuk Halvø area in central West<br />

Greenl<strong>and</strong>. This basin may be a southern extension <strong>of</strong><br />

the basin complex in the Melville Bay region (Fig. 1;<br />

Whittaker et al. <strong>19</strong>97); the <strong>of</strong>fshore area between 68° <strong>and</strong><br />

73°N is, however, covered by Palaeogene basalts <strong>and</strong> little<br />

is therefore known about the deeper-lying successions<br />

in this region. A small outcrop is known from Cape<br />

Dyer, eastern Baffin Isl<strong>and</strong> (Burden & Langille <strong>19</strong>90) <strong>and</strong><br />

outcrops <strong>of</strong> Cretaceous–Palaeogene sediments are also seen<br />

farther north in Arctic Canada on Bylot Isl<strong>and</strong> (Miall et<br />

al. <strong>19</strong>80; Miall <strong>19</strong>86; Harrison et al. <strong>19</strong>99) <strong>and</strong> on<br />

Ellesmere Isl<strong>and</strong> (Núñez-Betelu <strong>19</strong>94, Núñez-Betelu et<br />

al. <strong>19</strong>94a, b; Harrison et al. <strong>19</strong>99).<br />

During the Early Paleocene (Danian), the area <strong>of</strong>fshore<br />

southern West Greenl<strong>and</strong> was subjected to major<br />

uplift <strong>and</strong> erosion (Bonow et al. 2007). Sedimentation<br />

resumed in the Late Danian contemporaneously with<br />

the major episode <strong>of</strong> Paleocene volcanism in the<br />

Disko–Nuussuaq area <strong>and</strong> continued into the Holocene<br />

with a major hiatus spanning the Oligocene in the north<br />

<strong>and</strong> the mid-Eocene to mid-Miocene in the south<br />

(Dalh<strong>of</strong>f et al. 2003).<br />

56°W<br />

72°N<br />

71°N<br />

70°N<br />

69°N<br />

Svartenhuk<br />

Halvø<br />

Hareøen<br />

Nordfjord<br />

Mellemfjord<br />

50 km<br />

Ubekendt<br />

Ejl<strong>and</strong><br />

Uummannaq<br />

Fjord<br />

Itilli fault zone<br />

Disko<br />

KQ<br />

Qeqertarsuaq<br />

Vaigat<br />

53°W<br />

Upernivik<br />

Ø<br />

Aasiaat<br />

Uummannaq<br />

Nuussuaq<br />

Disko Bugt<br />

51°W<br />

Inl<strong>and</strong> Ice<br />

Ilulissat<br />

Grønne<br />

Ejl<strong>and</strong><br />

55°W 51°W<br />

Palaeogene intrusive<br />

complex<br />

?<br />

Ik<br />

Qeqertarsuaq<br />

?<br />

72°N<br />

71°N<br />

Extensional fault<br />

Fig. 10. Simplified geological map <strong>of</strong> the Nuussuaq Basin (after<br />

Chalmers et al. <strong>19</strong>99). Ik, Ikorfat fault zone; KQ, Kuu -<br />

gannguaq–Qunnilik Fault; DGR, Disko Gneiss Ridge. The<br />

<strong>of</strong>fshore geology is indicated by paler shades.<br />

Lower Palaeogene basalts<br />

Maastrichtian–Paleocene<br />

sediments<br />

Albian–Campanian<br />

sediments<br />

Precambrian basement<br />

Pre-volcanic fault<br />

Fault with lateral<br />

or alternating<br />

displacements<br />

21

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