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

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TSS 4–6. In late Maastrichtian – early Paleocene times, the stress system in the region changed and extension took place along NW–SE- and N–S-trending faults. These form the present eastern limit of the basin and displaced and rotated the major N–S-trending blocks in the basin (e.g. Chalmers et al. 1999). This trend is identical to several shear zones in the Precambrian basement east of Disko Bugt, suggesting that these shear zones exerted an influence on later faulting and the trend of a possible major transfer fault situated in the Vaigat area (Dam 2002, Wilson et al. 2006). Major faulting also occurred along the NW–SE-trending faults and the rift blocks show evidence of major erosion before being covered by upper Maastrichtian – lower Paleocene marine sediments and middle Paleocene volcanic rocks (e.g. Dam & Sønderholm 1998; Dam et al. 1998a). Birkelund (1965), Rosenkrantz & Pulvertaft (1969), J.M. Hansen (1980b) and Nøhr- Hansen (1996) noted that the Cretaceous faunas and floras in the Nuussuaq Basin are similar to those of the North American Interior Seaway while there is an overwhelming European affinity in the Danian, suggesting that an important change in palaeogeography and palaeoceanography took place during the latest Cretaceous and earliest Paleocene (Rosenkrantz & Pulvertaft 1969; J.M. Hansen 1980b; Nøhr-Hansen & Dam 1997). Three major tectonic episodes have been recognised in the latest Maastrichtian – earliest Paleocene, each associated with incision of valley systems and development of submarine canyons. The first of these episodes (TSS 4) is of latest Maastrichtian age and is represented by the Kangilia Formation in which two major SE–NW-trending submarine canyons have been documented from outcrops (Figs 11, 12B). The second, earliest Paleocene episode (TSS 5) is represented by the Tupaasat and Nuuk Qiterleq Members of the Quikavsak Formation. It was associated with major uplift of the basin and fluvial valley incision into Early Paleocene fault scarps and was characterised by catastrophic deposition (Figs 11, 12C). The third episode (TSS 6) was associated with renewed uplift during the Early Paleocene, and valleys were incised into the old valley system (Paatuutkløften Member of the Quikavsak Formation). Crossing the Kuuganng uaq– Qunnilik Fault, the incised fluvial valleys pass westwards into a major submarine canyon system. The sand-dominated fill of this canyon system is referred to the marine Agatdal Formation, named after equivalent valley-fill sediments in central Nuussuaq. This episode was followed by very rapid subsidence. The incised valleys were eventually filled with transgressive estuarine and shoreface deposits before they were blanketed by offshore tuffaceous mudstones referred to the Eqalulik Formation (Figs 11, 12D) immediately prior to extrusion of picritic hyaloclastite breccias of the Vaigat Formation (Figs 11, 12E). The recurrent episodes of uplift and incision of submarine canyons and valleys in Atane Formation deposits in the eastern outcrop area resulted in major redistribution of sandstones into the deep-water environments to the west, and major turbidite sandstone bodies are thus suspected to be regionally present. TSS 7. Extrusion of the volcanic succession can be divided into two phases and is related to continental break-up in the Labrador Sea region (A.K. Pedersen et al. 2006a, and references therein). The first phase, of Selandian to Thanetian (late Paleocene) age, was dominated by extrusion of olivine-rich basalts and picrites (Figs 11, 12E) and later by more evolved, plagioclase-phyric basalts (Vaigat and Maligât Formations of the West Greenland Basalt Group). The first volcanism recorded in the Nuussuaq Basin took place in a marine environment and eruption centres were located in the westernmost part of the basin (Fig. 12E). Thick hyaloclastite fans of the Anaanaa and Naujánguit Members prograded towards the east (Figs 12F, 16). As the volcanic front moved eastwards, large lakes were formed between the volcanic front to the west and the cratonic crystalline basement to the east (Fig. 12F), giving rise to synvolcanic lacustrine deposits (Atanikerluk Formation). TSS 8. During the Eocene, magmatic activity in the Nuussuaq Basin resumed with an episode of intrusion of dyke swarms and extrusion of basalts and sparse comendite tuffs of the Kanísut Member. The volcanic succession was dissected by N–S-trending faults and a new NE–SW fault trend (the Itilli fault zone; Figs 10, 11). The tectonic activity probably waned during Late Palaeogene time, and during the Neogene the area was lifted by 1–2 km to its present elevation (Chalmers 2000; Bonow et al. 2007, and references therein; Japsen et al. 2009). 26
Nuussuaq Group new group History. The Nuussuaq Group comprises the pre- and synvolcanic Cretaceous–Paleocene sediments on a number of islands and peninsulas in West Greenland between 69° and 72°N (Fig. 10). Intrabasaltic sediments are not included in the Nuussuaq Group but in the overlying West Greenland Basalt Group, with the local exception of thin, intra-volcanic wedges of sediment that demonstrably interdigitate with prograding hyaloclastite breccias and lavas of the lowermost West Greenland Basalt Group. Initial investigations of the geology date back to K.L. Giesecke, who described the area in detail around 1810 (in: Steenstrup 1910), Rink (1853, 1857) and Nordenskiöld (1871); the latter erected three litho - stratigraphic units for the pre-volcanic sediment, separate from the intra-basaltic Ifsorisok Beds (Fig. 13; see section on ‘Previous work’ above). However, these units were not recognised by L. Koch (1929) in his exhaustive account of the stratigraphy of Greenland. He referred all the sediments to one formation – the Nugsuak For - mation – but also predicted that “future investigations will doubtlessly result in a division of the beds which I have included in one formation, into several formations” (L. Koch 1929 p. 258). A more detailed lithostratigraphical scheme was developed as a result of the work during the Nûgssuaq Expeditions 1938–1968 (see section on ‘Previous work’ above; Rosenkrantz 1970). This was, however, rather incomplete and included units, especially at member level, that were not formally described (Fig. 13). Name. After the Nuussuaq peninsula, where the most extensive outcrops occur (Fig. 10). Type area. The south coast of Nuussuaq, where the most complete and best exposed sections of the Nuussuaq Group occur, e.g. at Atanikerluk, the coastal slopes at Paatuut, along the western slope of the Ataata Kuua river, and in river gorges in the southern part of the Itilli val- Nordenskiöld 1871 Sinnifiklagren* Ifsorisoklagren* Öfre Atanekerdluk-lagren Atanelagren (N. Atanekerdluklagren) Koch 1929 Nugsuak Formation Troelsen 1956 Sinnifik Fm* Ifsorisok Fm* Upper Atanikerdluk Fm Patoot Fm Atane Fm Rosenkrantz 1970 Agatdal Fm Kangilia Fm Marine Upper Cretaceous Henderson et al. 1976 Ifsorisok Fm* Vaigat Fm Maligât Fm Pautut Fm Komelagren Kome Fm Kome Fm U. Atanikerdluk Fm Agatdal Fm Kangilia Fm Marine Upper Cretaceous Atane Fm Upernivik Næs Fm Present paper Ifsorisok Mb* Maligât Fm Vaigat Atanikerluk Fm Fm Eqalulik Fm Agatdal Quikavsak Fm Fm Kangilia Fm Upernivik Næs Fm Itilli Fm Atane Fm Slibestensfjeldet Fm Kome Fm Nuussuaq Group WGBG * Intrabasaltic sediments Fig. 13. Comparison of former lithostratigraphical subdivisions and the scheme used in this paper. All pre-volcanic and the earliest synvolcanic sedimentary rocks of the Nuussuaq Basin constitute the Nuussuaq Group (new), which comprises 10 formations (new or revised). WGBG, West Greenland Basalt Group. 27
Page 1 and 2: GEOLOGICAL SURVEY OF DENMARK AND GR
Page 4 and 5: Contents Abstract . . . . . . . . .
Page 7 and 8: Preface The onshore Cretaceous-Pale
Page 9 and 10: Introduction The Nuussuaq Basin bel
Page 11 and 12: chemistry of the Nuussuaq Basin hav
Page 13 and 14: Fig. 5. Plant fossils from the Atan
Page 15 and 16: Peak 2010 m Peak 1900 m Peak 1760 m
Page 17 and 18: A lithostratigraphy for the marine
Page 19 and 20: to provide further funding for stud
Page 21 and 22: DGR Geological setting As a result
Page 23 and 24: TSS 8 Agatdal Fm Eqalulik Fm Kangil
Page 25: A Svartenhuk Halvø 50 km B Hinterl
Page 29 and 30: ley (Figs 2, 40, 65). The section a
Page 31 and 32: Central Nuussuaq Agatdalen South co
Page 33 and 34: 3 10 4 6 5 Qorlortorssuaq Slibesten
Page 35 and 36: volcanic sediments are referred to
Page 37 and 38: Fig. 20. View from Uummannaq toward
Page 39 and 40: In the Kuuk area, the sediments ove
Page 41 and 42: m m 15 14 14 13 12 11 10 9 8 7 6 5
Page 43 and 44: Kome Formation m 40 30 20 D tial re
Page 45 and 46: Fig. 28. Reference locality of the
Page 47 and 48: Vaigat Fm Vesterfjeld Slibestensfje
Page 49 and 50: Gilbert delta in the Ikorfat area (
Page 51 and 52: 150 300 450 100 250 400 m 550 50 20
Page 53 and 54: Fig. 36. Outcrop of the Upernivik N
Page 55 and 56: Correlation. The Upernivik Næs flo
Page 57 and 58: 12’ 09’ 15’ 06’ 03’ Saqqa
Page 59 and 60: m 0 GGU 247801 200 400 247815 ★
Page 61 and 62: wave-rippled sand streaked mudstone
Page 63 and 64: the formation in the marine mudston
Page 65 and 66: d d Fig. 47. Type locality of the S
Page 67 and 68: Fig. 49. Cross-bedded medium- to co
Page 69 and 70: and Qaarsut (Fig. 22). Its wider di
Page 71 and 72: Fig. 52. Two closely spaced section
Page 73 and 74: Type section. The type section of t
Page 75 and 76: Fig. 56. Delta front succession of
Page 77 and 78:
Fig. 59. The Kingittoq Member at Ki
Page 79 and 80:
sh L sh ch delta front Vaigat Forma
Page 81 and 82:
Fig. 63. Type locality of the Itivn
Page 83 and 84:
782 Quaternary cover 54° 888 Malig
Page 85 and 86:
Kuugannguaq-Qunnilik Fault and is o
Page 87 and 88:
and include clasts of intraformatio
Page 89 and 90:
deposited in a base-of-slope and ba
Page 91 and 92:
VK 53°30’ 53°15’ Niaqornat Tu
Page 93 and 94:
Umiivik-1 m Overburden ★ ★ No p
Page 95 and 96:
76). Heavily bioturbated interbedde
Page 97 and 98:
Fig. 78. Type locality of the Kussi
Page 99 and 100:
A B Itilli Formation Kussinerujuk M
Page 101 and 102:
160 140 120 100 Vaigat Formation Eq
Page 103 and 104:
Fig. 85. Mudstones and conglomerati
Page 105 and 106:
Fig. 87. Type section of the Kangil
Page 107 and 108:
m 150 140 130 120 110 100 90 Kangil
Page 109 and 110:
channellised, high-density currents
Page 111 and 112:
Thickness. The Annertuneq Conglomer
Page 113 and 114:
Fig. 96. A: Type locality of the Oy
Page 115 and 116:
On Svartenhuk Halvø, on the east s
Page 117 and 118:
Fig. 100. Reference locality of the
Page 119 and 120:
Tupaasat Member Atane Formation Fig
Page 121 and 122:
ever, have a fluvio-lacustrine orig
Page 123 and 124:
etween Tupaasat and Nuuk Qiterleq a
Page 125 and 126:
Vaigat Formation sill Quikavsak For
Page 127 and 128:
Fig. 112. The sharp boundary betwee
Page 129 and 130:
Agatdal Formation Eqalulik Formatio
Page 131 and 132:
Fig. 116. Basal conglomerate unit o
Page 133 and 134:
heterolithic deposits of the Kangil
Page 135 and 136:
GANE#1 Vaigat Fm Anaanaa Mb m Hyalo
Page 137 and 138:
Fig. 121. Well reference section of
Page 139 and 140:
Pedersen 1978). The beds are usuall
Page 141 and 142:
In detail, however, the boundary be
Page 143 and 144:
Fig. 126. Composite type section of
Page 145 and 146:
m m 240 340 m Pingu Member 230 230
Page 147 and 148:
Naujât Member Atane Formation, Kin
Page 149 and 150:
The TOC [Total Organic Carbon] cont
Page 151 and 152:
Fig. 133. Correlation of the member
Page 153 and 154:
Fig. 135. Type locality of the Ping
Page 155 and 156:
Fig. 137. Lower, sharp boundary of
Page 157 and 158:
m 130 125 110 t t invasive lava low
Page 159 and 160:
Fig. 141. Upper part of the Assoq M
Page 161 and 162:
Brown, R. 1875: Geological notes on
Page 163 and 164:
a rosetted spreite trace fossil: Da
Page 165 and 166:
ing bark from the Nûgssuaq peninsu
Page 167 and 168:
1998: The syn-volcanic Naajaat lake
Page 169 and 170:
Appendix: Place names and localitie
Page 171:
Place name Place name P Paatuut sou
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Geological Survey of Denmark and Greenland Bulletin 19 ... - Geus

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