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

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interpreted as a lacustrine flooding surface which can be mapped westwards into the volcanic terrain where it separates subaerial lavas of the Naujánguit Member from overlying hyaloclastite breccias at or just above the base of the Ordlingassoq Member (A.K. Pedersen 1985; A.K. Pedersen et al. 1993; G.K. Pedersen et al. 1998) (Fig. 131). On eastern Disko, the lowest member of the Atanikerluk Formation is the dominantly fluvial Akunneq Member, and the base of this member constitutes the lower boundary of the formation; this is well exposed in the coastal section from Pingu to Nuu gaarsuk (Figs 132, 133). The upper boundary of the Atanikerluk Formation is either a recent erosion surface or the boundary with volcanic or volcaniclastic deposits of the Vaigat or Maligât Formations (Figs 16, 131). Geological age. The Atanikerluk Formation is dated by dinocysts, pollen or plant macrofossils, and is constrained by magnetostratigraphic and radiometric dating of the correlative volcanic units. A maximum age for the Atanikerluk Formation is obtained from the NP4 – possibly early NP5 marine dinocysts in the underlying Eqalulik Formation (Nøhr-Hansen et al. 2002). Samples from the volcanic Ordlingassoq and Rinks Dal Members give radiometric ages of 60.7–61.1 ± 0.5–1.0 Ma, recalculated from Storey et al. (1998). This indicates an early to mid-Paleocene (possibly Selandian) age for the Atanikerluk Formation according to the timescale of Gradstein et al. (2004) and Ogg et al. (2008). Correlation. The two regional, coarsening-upward successions recognised in the Atanikerluk Formation correlate with the volcanic Ordlingassoq and Rinks Dal Members of the Vaigat and Maligât Formations respectively (Fig. 131). Correlation of individual members of the Atanikerluk Formation to strata of the Vaigat For - mation on Disko presents some difficulties due to lack of exposures along the north coast of the island. The Atanikerluk Formation is younger than the Eqalulik Formation despite the similarity in macroplant fossils between the Abraham and the Naujât Members. Subdivision. The Atanikerluk Formation is subdivided into five members: the Naujât, Akunneq, Pingu, Umiussat and Assoq Members (Fig. 123). Naujât Member revised member History. The Naujât Member was established by Koch (1959). Its distribution is expanded here, but otherwise the definition of the member is retained. Name. The member is named from a small cove (modern spelling Naajaat) on the south coast of Nuussuaq, just west of Saqqaqdalen (Fig. 40; Koch 1955). Distribution. The distribution of the Naujât Member along the south-east coast of Nuussuaq was mapped by Koch (1959 plates 5–7). He recognised the Naujât Member in almost continuous outcrops and scree-covered slopes on the western side of Saqqaqdalen and along Naujât Member U S 70 m S Q Atane Formation Fig. 129. Type locality of the Naujât Member (Atanikerluk Formation) along the western slope of Saqqaqdalen near Naajaat (for location, see Fig. 40). An angular unconformity is seen between the Atane Formation and the Quikavsak Formation (Q). The latter is conformably overlain by lacustrine mudstones of the Naujât Member, which is cut by a sill (S). The outcrop of pale yellow sandstones in the distance belongs to the Umiussat Member (U). 146
Naujât Member Atane Formation, Kingittoq Member Fig. 130. Outcrop of the Naujât Member overlying the Atane Formation at Eqip Inaarsuata Qaqqaa, at the northern end of the Saqqaqdalen valley (located as EIQ in Fig. 2). The lacustrine mudstones drape erosional relief on the top of the Atane Formation. The Naujât Member is c. 200 m thick. the coast from Naajaat to Kingittoq (Fig. 40). The member was traced in scree and landslides in the Paatuut area, and, at Ataata Kuua, in a thin succession between the mudstones of the Eqalulik Formation and the hyaloclastite breccias of the Ordlingassoq Member below Point 1010 m (Figs 15, 16; A.K. Pedersen et al. 1993, 2007b). In Saqqaqdalen, the Naujât Member continues northwards for about 25 km along the upper western slopes of the valley (A.K. Pedersen et al. 2007a). On Disko, the Naujât Member is known from scattered outcrops along the north coast at Qorlortorsuaq and towards Nuugaarsuk (G.K. Pedersen et al. 1998 fig. 12). The delineation of the member on Disko is also discussed under the distribution of the Pingu Member. Type section. The type section was described in the southwestern end of Saqqaqdalen, above Naajaat, by Koch (1959; Figs 124, 129). The type section is located at 70°04.10´N, 52°10.78´W. Reference section. A reference section is proposed at Kingittoq (Fig. 127). A sedimentological log is shown in G.K. Pedersen et al. (1998 fig. 10). Thickness. The Naujât Member is thickest on Nuussuaq, up to 230 m at Kingittoq (Koch 1959) and in Saqqaqdalen (G.K. Pedersen et al. 1998). On Disko, the member is thin; up to 10 m are preserved at Qorlortorsuaq on the north coast between Qullissat and Asuk (A.K. Pedersen 1985). Lithology. The Naujât Member comprises dark grey to black mudstones with thin, discontinuous layers of sandstones and thin tuff beds. The tuffs are strongly altered and the original chemical composition cannot be determined, but examination of thin sections suggests that the tuffs correlate with the Vaigat Formation. Mineralogically, the mudstones are dominated by kaolinite and quartz with minor feldspar, illite and smectite. Gibbsite has only been identified in 15% of the samples, mostly from the upper part of the member. Pyrite has not been detected. 147
Page 1 and 2:
GEOLOGICAL SURVEY OF DENMARK AND GR
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Contents Abstract . . . . . . . . .
Page 7 and 8:
Preface The onshore Cretaceous-Pale
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Introduction The Nuussuaq Basin bel
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chemistry of the Nuussuaq Basin hav
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Fig. 5. Plant fossils from the Atan
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Peak 2010 m Peak 1900 m Peak 1760 m
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A lithostratigraphy for the marine
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to provide further funding for stud
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DGR Geological setting As a result
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TSS 8 Agatdal Fm Eqalulik Fm Kangil
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A Svartenhuk Halvø 50 km B Hinterl
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Nuussuaq Group new group History. T
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ley (Figs 2, 40, 65). The section a
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Central Nuussuaq Agatdalen South co
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3 10 4 6 5 Qorlortorssuaq Slibesten
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volcanic sediments are referred to
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Fig. 20. View from Uummannaq toward
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In the Kuuk area, the sediments ove
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m m 15 14 14 13 12 11 10 9 8 7 6 5
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Kome Formation m 40 30 20 D tial re
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Fig. 28. Reference locality of the
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Vaigat Fm Vesterfjeld Slibestensfje
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Gilbert delta in the Ikorfat area (
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150 300 450 100 250 400 m 550 50 20
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Fig. 36. Outcrop of the Upernivik N
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Correlation. The Upernivik Næs flo
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12’ 09’ 15’ 06’ 03’ Saqqa
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m 0 GGU 247801 200 400 247815 ★
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wave-rippled sand streaked mudstone
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the formation in the marine mudston
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d d Fig. 47. Type locality of the S
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Fig. 49. Cross-bedded medium- to co
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and Qaarsut (Fig. 22). Its wider di
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Fig. 52. Two closely spaced section
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Type section. The type section of t
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Fig. 56. Delta front succession of
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Fig. 59. The Kingittoq Member at Ki
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sh L sh ch delta front Vaigat Forma
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Fig. 63. Type locality of the Itivn
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782 Quaternary cover 54° 888 Malig
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Kuugannguaq-Qunnilik Fault and is o
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and include clasts of intraformatio
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deposited in a base-of-slope and ba
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VK 53°30’ 53°15’ Niaqornat Tu
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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: m m 240 340 m Pingu Member 230 230
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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