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

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Slibestensfjeldet Formation new formation History. The Slibestensfjeldet Formation has previously been described as Unit 2, an informal lithological unit in the Slibestensfjeldet–Ikorfat area (Midtgaard 1996b). Name. After the prominent mountain of Slibestensfjeldet on the north coast of Nuussuaq (Fig. 22). Distribution. The Slibestensfjeldet Formation is known only from the north coast of Nuussuaq between Vesterfjeld and Ikorfat (Fig. 22; Midtgaard 1996b). The formation is not known to be preserved north of Nuussuaq, but it is expected to continue southwards, for some distance, in the subsurface. The extent of the formation west of the Ikorfat fault is not known. Type section. The type section is at Kussinikassaq where the formation is thickest (Figs 22, 30), immediately east of the basement high at Ikorfat beginning at an altitude of c. 60 m a.s.l. The base of the type section is located at 70°46.20´N, 53°03.37´W. Reference sections. Reference sections are found at Vesterfjeld, c. 860 m a.s.l., and in two gullies on Slibe - stensfjeldet c. 1 km east of Talerua, beginning at an altitude of c. 320 m a.s.l. (Fig. 30). Thickness. The Slibestensfjeldet Formation increases in thickness from 90 m at Vesterfjeld to c. 200 m at Kus - sinikassaq (Figs 22, 30). Lithology. A considerable lateral change in lithology characterises the Slibestensfjeldet Formation from Vesterfjeld to Ikorfat, a distance of approximately 10 km (Fig. 30; Midtgaard 1996b). At the type section, the formation is dominated by mudstones, interbedded with 0.2–2 m thick sandstone beds, which are structureless, parallel laminated, cross-laminated or hummocky cross-stratified (Figs 30, 31, 32). The mudstones contain c. 5% carbon, almost entirely of organic origin, traces of pyrite are restricted to a thin coal bed, and the calculated carbon/ sulphur (C/S) ratios are c. 100. The sandstone interbeds in the c. 200 m thick mudstone unit become increasingly common upwards. At the top of this coarsening-upward succession is a medium-grained sandstone unit 5 m thick, showing steeply dipping foresets; this facies is restricted to the areas west of the Talerua fault. In the east, the formation is dominated by sandstones interbedded with thin mudstones and conglomerate beds. Laminated black mudstones with sand streaks are abruptly overlain by very fine- to fine-grained, well-sorted sandstones dominated by horizontal lamination and hummocky crossstratification, whereas low-angle cross-bedding and wave ripple cross-lamination are subordinate (Midtgaard 1996a). The sandstones are often slightly bioturbated. Thin conglomerate beds composed of well-rounded clasts and showing erosional bases and wave-rippled tops, recur throughout the formation (Midtgaard 1996a). Fossils. The mudstones contain an assemblage of brackish-water dinocysts dominated by Pseudoceratium interiorense whereas the pollen Rugubivesiculites rugosus is absent (Figs 29, 30). Plant macrofossils from the lowermost part of the formation are referred to the Ikorfat flora, which has been assigned to the Early–Middle Albian (Boyd 1998a, b, c, 2000). Depositional environment. The widely distributed and thick coal bed at the base of the Slibestensfjeldet Formation indicates accumulation of peat under a slowly rising ground-water table. The overlying fine-grained, wave-rippled sandstones are interpreted as lake shoreline deposits and indicate an increasing rate of water level rise, which continued to the deposition of mudstones at depths below wave-base. In the mudstones, the C/S ratios of c. 100 and the stratigraphical position between the fluvial Kome and the fluvial Ravn Kløft Member indicate that the Slibestensfjeldet Formation was deposited in a large and deep lake. The overall, coarsening-upward, vertical facies succession is interpreted to record the infill of the lake and progradation of the shoreline. The presence of dinocysts, which are interpreted as brackish-water forms, suggests that the lake was connected to a coastal lagoon. The lake increased in depth from east to west, and wave-influenced, relatively shallow-water facies are only known from Vesterfjeld and Slibestensfjeldet. The conglomerate beds represent transgressive lags created by wave erosion and winnowing. The nearshore sandstones accu - mulated in large complex bedforms overprinted by wave-ripples (Midtgaard 1996a). The upper part of the Slibe stensfjeldet Formation locally developed as a Facing page: Fig. 30. Type section of the Slibestensfjeldet Formation at Kus sini - kassaq; reference sections of the formation at Vesterfjeld and Slibestensfjeldet. Note the marked increase in thickness towards the west (Kussinikassaq). All logs are from the north coast of Nuussuaq (Fig. 22). For legend, see Plate 1; GD, Gilbert Delta; Ps, palaeosol. 46
Vaigat Fm Vesterfjeld Slibestensfjeldet Kussinikassaq Slibestensfjeldet Formation Atane Formation Ravn Kløft Member Slibestensfjeldet Formation Ravn Kløft Member mud GD sand pebbles Slibestensfjeldet Formation Ravn Kløft Member GD c. 50 m not shown m 20 10 Kome Fm mud Ps sand pebbles 0 Kome Fm mud Ps sand pebbles 47
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 and 26: A Svartenhuk Halvø 50 km B Hinterl
Page 27 and 28: Nuussuaq Group new group History. T
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: Fig. 28. Reference locality of the
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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