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