8th International Nannoplankton Association Conference


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Emma Sheldon:
New nannofossil dating of the initial Early Paleocene volcanism in central W Greenland

New nannofossil data, from the Lower Paleocene succession in the Nuussuaq Basin, onshore W Greenland (Figure a), has been integrated with dinoflagellate cyst dating to produce a detailed biostratigraphic zonation. The succession has been divided into five dinoflagellate cyst zones (Trithyrodinium evittii (lowermost), Cerodinium pannuceum, Senegalinium iterlaaense, Palaeocystodinium bulliforme and Alisocysta margarita) which correlate with the global nannofossil (NP) biozonation scheme of Martini (1971) and published schemes from Denmark and the Northern Hemisphere (Perch-Nielsen, 1979; Thomsen, 1995; Varol, 1998).

Previous palynological dating (Hansen, 1980; Piasecki et al., 1992; Nøhr-Hansen, 1997a, b; Christiansen et al., 1997) of Paleocene sediments, at various localities on Nuussuaq, revealed ages which correlated with NP3-NP8. Perch-Nielsen (1973) and later Jürgensen & Mikkelsen (1974) used nannofossils to date Paleocene sections at Agatkløft (C Nuussuaq), Maraat Killiit (SW coast) and Kangilia, respectively, as Late Danian NP3.

In this work, nannofossil samples were taken from 4 wells (GANE#1, GANK#1, GANW# and GRO#3), on the SW coast of Nuussuaq, and three outcrop sections on the N coast (Kangilia, Annertuneq and Danienrygge). The samples yielded low-abundance and -diversity nannofossil assemblages; most specimens were very poorly preserved and were often obscured by amorphous organic material. As a result of this, samples were prepared using a 10% solution of potassium hydroxide to remove humic material.

The studied sections yielded nannofossil assemblages ranging from NP1-NP4. The stratigraphically most important nannofossils include Placozygus sigmoides, Neochiastozygus modestus, Prinsius martinii, Neochiastozygus saepes, Chiasmolithus cf. C. bidens and Neochiastozygus perfectus. First and last occurrences of these marker fossils have been correlated with the dinoflagellate cyst zones and nannofossil zonation schemes mentioned above (Figure b).

A rifting event, preluding initial volcanism in W Greenland, was associated with substantial uplift and repeated erosion and infilling of incised, subaerial valleys and submarine canyons, resulting in basin-wide unconformity. On the basis of nannofossil data, it is now possible to date these events (Nøhr-Hansen et al., subm.). Uplift was followed by a phase of very rapid subsidence shortly before the extrusion of picritic hyaloclastic breccias (Dam et al., 1998).

An assemblage including N. perfectus, N. cf. N. modestus, C. cf. C. bidens and P. dimorphosus dates the youngest sandstones lying directly below the first Paleocene volcanics as upper NP4, correlating with the base of the 'Alisocysta margarita' dinoflagellate cyst biozone (latest Danian or possibly earliest Selandian). These new biostratigraphic results compliment published 40Ar/39Ar data (Storey et al., 1998) and magnetostratigraphic data (Riisager & Abrahamsen, 1999), allowing a relatively accurate dating of the initiation of volcanism onshore W Greenland and the N Atlantic Igneous Province.


Dam, G., Larsen, M. & Sønderholm, M. 1998. Sedimentary response to mantle plumes: Implications from Paleocene onshore successions, West and East Greenland. Geology, 26(3): 207-210.

Hansen, J.M. 1980. Stratigraphy and structure of the Paleocene in central West Greenland and Denmark. Unpubl. lic. scient. thesis, Geological Institute, University of Copenhagen: 156pp.

Jürgensen, T. & Mikkelsen, N. 1974. Coccoliths from volcanic sediments (Danian) in Nûgssuaq, West Greenland. Geological Society of Denmark Bulletin, 23: 225-230.

Martini, E. 1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. Proceedings of the II Planktonic Conference, Roma, 1970, 2: 739-785.

Nøhr-Hansen, H. 1997a. Palynology of the boreholes GANE#1, GANK#1and GANT#1, Nuussuaq, West Greenland. Danmarks og Grønlands Geologiske Undersøgelse Rapport, 1997/89: 22pp.

Nøhr-Hansen, H. 1997b. Palynology of the GRO#3 well, Nuussuaq, West Greenland. Danmarks og Grønlands Geologiske Undersøgelse Rapport, 1997/151: 19 pp.

Perch-Nielsen, K. 1973. Danian/Maastrichtian coccoliths from Nûgssuaq, West Greenland. Bulletin of the Geological Society of Denmark, 22: 79-82.

Perch-Nielsen, K. 1979. Calcareous nannofossil zonation at the Cretaceous/Tertiary boundary in Denmark. In: T. Birkelund & R.G. Bromley (Eds). Cretaceous-Tertiary boundary events I. Proceedings, The Maastrichtian and Danian of Denmark. University of Copenhagen: 115-135.

Piasecki, S., Larsen, L.M., Pedersen, A.K. & Pedersen, G.K. 1992. Palynostratigraphy of the Lower Tertiary volcanics and marine clastic sediments in the southern part of West Greenland Basin: implications for the timing and duration of the volcanism. Rapport Grønlands Geologiske Undersøgelse, 154: 13-31.

Riisager, P. & Abrahamsen, N. 1999. Magnetostratigraphy of Palaeocene basalts from the Vaigat Formation of West Greenland. Geophysical Journal International, 137: 774-782.

Storey, M., Duncan, R.A., Pedersen, A.K., Larsen, L.M. & Larsen, H.C. 1998. 40Ar/39Ar geochronology of the West Greenland Tertiary volcanic province. Earth and Planetary Science Letters, 160: 569-586.

Thomsen, E. 1995. Kalk og kridt i den danske undergrund. In: O.B. Nielsen (Ed.). Danmarks geologi fra Kridt til i dag. Aarhus Geokompendier, Aarhus University: 1, 31-67.

Varol, O. 1998. Palaeogene. In: P.R. Bown (Ed.). Calcareous Nannofossil Biostratigraphy. Chapman & Hall: 200-224.


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