Abstract
Fission track ages have been measured for 12 sphenes, 18 zircons and 25 apatites separated largely from Lower Tertiary magmatic rocks of East Greenland, with a few examples from Caledonian rocks. The sphene and zircon ages of Caledonian rocks agree with other radiometric ages but apatite is strongly discordant indicating that these rocks cooled very slowly over a 200 m.y. period. It was not until the Permian/Lower Jurassic that they finally cooled below 100 ° C, possibly as a consequence of uplift and erosion at this time in connection with extensive rifting. No evidence of a Tertiary imprint has been found in these rocks.
Layered gabbros, such as Skaergaard, were emplaced at about the same time (ca. 54 m.y.) as the latest plateau basalts. Some evidence of syenitic activity from this period occurs in the Angmagssalik area ca. 400 km to the south but the syenites of Kangerdlugssuaq cluster around 50 m.y. The Gardiner ultramafic alkaline complex and some of the offshore gabbros apparently also were emplaced at about 50 m.y. Late dykes in the Kangerdlugssuaq area were emplaced over a considerable time span (43-34 m.y.) in keeping with their variable petrographic character, and the Kialineq centre was formed at 36.2±0.4 m.y.
Intrusions of the Masters Vig area differ in age. Kap Simpson and Kap Parry to the northeast were emplaced around 40 m.y. whereas the Werner Bjerge complex is the youngest igneous activity so far identified in Greenland with an age of 30.3±1.3 m.y.
Many apatites give strongly discordant ages of about 36 m.y. and these are concentrated in the area of a major domal uplift centred on Kangerdlugssuaq. The uplift is older than these ages but on field evidence post-dates the basalts. It probably formed in conjunction with alkaline magmatism at ca. 50 m.y. Cooling below ca. 200 ° was slow for these intrusions and was probably controlled by a number of factors including erosion of the dome, high heat flow caused by continuing dyke injection and regional plateau uplift. The last is believed to have taken place about 35 m.y. ago at the time of emplacement of the Kialineq plutons and last dykes. Renewed rapid erosion and declining heat flow at this time led to rapid cooling of the rocks now at the surface to below 100 °.
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References
Ahlman, H.W.: Studies in northeast Greenland, 1939–1940. Part I. The main morphological features of northeast Greenland. Geogr. Annlr. 23, 148–182 (1941)
Bearth, P.: On the alkali massif of the Werner Bjerge in East Greenland. Meddr. Grønland 153, Nr4, 1–63 (1959)
Beckinsale, R.D., Brooks, C.K., Rex, D.C.: K-Ar ages for the Tertiary of East Greenland. Bull. Geol. Soc. Den. 20, 27–37 (1970)
Birkelund, T., Perch-Nielsen, K.: Late Palaeozoic-Mesozoic evolution of central East Greenland. In: Geology of Greenland (A. Escher, W.S. Watt, eds.), pp 305–339. Geol. Surv. Greenland 1976
Birkenmajer, K.: Report on investigations of Tertiary sediments at Kap Brewster, Scoresby Sund, East Greenland. Rapp. Grønlands Geol. Unders. 48, 85–91 (1972)
Brooks, C.K.: Tertiary of East Greenland — a volcanic and plutonic record of continental break-up. Mem. Am. Assoc. Pet. Geol. 19, 150–160 (1973a)
Brooks, C.K.: Rifting and doming in southern East Greenland. Nature (London) Phys. Sci. 244, 23–25 (1973b)
Brooks, C.K.: Geomorphological observations at Kangerdlugssuaq, East Greenland. Greenland Geoscience 1, (in press)
Brooks, C.K., Fawcett, J.J., Gittins, J.: Caledonian magmatic activity in south-eastern Greenland. Nature 260, 694–695 (1976)
Brooks, C.K., Gleadow, A.J.W.: A fission track age for the Skaergaard intrusion and the age of East Greenland basalts. Geology 5, 539–540 (1977)
Brooks, C.K., Rønsbo, J.G., Nielson, T.F.D.: Leucite from East Greenland: A new petrographic sub-province of the Tertiary North Atlantic province. Bull. Geol. Soc. Den. 24, 93–98 (1975)
Brooks, C.K., Rucklidge, J.C.: A Tertiary lamprophyre dyke with high pressure xenoliths and megacrysts from Wiedemans Fjord, East Greenland. Contrib. Mineral Petrol. 42, 197–212 (1973)
Brooks, C.K., Rucklidge, J.C.: Strongly undersaturated Tertiary volcanic rocks from the Kangerdlugssuaq area, East Greenland. Lithos 7, 239–248 (1974)
Brown, P.E.: A layered plutonic complex of alkali basalt parentage: the Lilloise intrusion, East Greenland. J. Geol. Soc. London 129, 405–418 (1973)
Brown, P.E., Breemen, O. van, Noble, R.H., Macintyre, R.M.: Mid-Tertiary igneous activity in East Greenland — the Kialineq complex. Contrib. Mineral. Petrol. 64, 109–122 (1977)
Brown, P.E., Brown, R.D., Chambers, A.D., Soper, N.J.: Fractionation and assimilation in the Borjtinderne Syenite, East Greenland. Contrib. Mineral. Petrol. 67, 25–34 (1978)
Coe, K.: The Hurry Inlet Granite and related rocks of Liverpool Land East Greenland. Grønlands Geol. Unders. Bull. 115, 1–34 (1975)
Deer, W.A.: Tertiary igneous rocks between Scoresby Sund and Kap Gustav Holm, East Greenland. In: Geology of Greenland (A. Escher, W.S. Watts, eds.), pp 405–429. Geol. Surv. Greenland 1976
Fitch, F.J., Hooker, P.J., Miller, J.A., Brereton, N.R.: Glauconite dating of Palaeocene-Eocene rocks from East Kent and the timescale of Palaeogene volcanism in the North Atlantic region. J. Geol. Soc. London 135, 499–512 (1978)
Fleischer, R.L., Price, P.B., Walker, R.M.: Effects of temperature, pressure and ionization on the formation and stability of fission tracks in minerals and glasses. J. Geophys. Res. 70, 1497–1502 (1965)
Frisch, W., Keusen, H.: Gardiner intrusion, an ultramafic complex at Kangerdlugssuaq, East Greenland. Grønlands Geol. Unders. Bull. 122, 1–62 (1977)
Gleadow, A.J.W.: Fission track evidence for the evolution of rifted continental margins. In: Short papers of the fourth international conference on geochronology, cosmochronology and isotope geology (R.E. Zartman, ed.). U.S. Geol. Surv. Open File Rep. 78–701, 146–148 (1978)
Gleadow, A.J.W., Hurford, A.J., Quaife, R.: Fission track dating of zircons: improved etching techniques. Earth Planet. Sci. Lett. 33, 273–276 (1976)
Gleadow, A.J.W., Lovering, J.F.: Fission track geochronology of King Island, Bass Strait, Australia: relationship to continental rifting. Earth Planet. Sci. Lett. 37, 429–437 (1978a)
Gleadow, A.J.W., Lovering, J.F.: Thermal history of granitic rocks from western Victoria: a fission track dating study. J. Geol. Soc. Aust. 25, 323–340 (1978b)
Haller, J.: Tectonic map of East Greenland (1∶500,000). An account of tectonism, plutonism and volcanism in East Greenland. Meddr. Grønland 171, Nr 5, 1–286 (1970)
Haller, J.: Geology of the East Greenland Caledonides. London: Wiley 1971
Hansen, B.T., Steiger, R.H.: The geochronology of the Scoresby Sund area I: Rb-Sr mineral ages. Rapp. Grønlands Geol. Unders. 37, 55–57 (1971)
Harrison, T.M., Armstrong, R.L., Naeser, C.W., Harakal, J.E.: Geochronology and thermal history of the Coast Plutonic Complex, near Prince Rupert, British Columbia. Can. J. Earth Sci. 16, 400–410 (1979).
Krishnaswami, S., Lal, D., Prabhu, N., Macdougall, D.: Characteristics of fission tracks in zircon: applications to geochronology and Cosmology. Earth Planet. Sci. Lett. 22, 51–59 (1974)
Larsen, H.C.: Offshore continuation of East Greenland dyke swarm and North Atlantic ocean formation. Nature 274, 220–223 (1978)
Naeser, C.W., Faul, H.: Fission track annealing in apatite and sphene. J. Geophys. Res. 74, 705–710 (1969)
Naeser, C.W., Forbes, R.B.: Variation of fission track ages with depth in two deep drill holes (abs.). Trans. Am. Geophys. Union 57, 353 (1976)
Naeser, C.W., Johnson, N.M., McGee, V.E.: A practical method of estimating standard error of age in the fission-track dating method. In: Short papers of the fourth international conference on geochronology, cosmochronology and isotope geology (R.E. Zartman, ed.). U.S. Geol. Surv. Open File Rep. 78–701, 303–305 (1978)
Nielsen, T.F.D.: Possible mechanism of continental breakup in the North Atlantic. Nature 253, 182–184 (1975)
Nielsen, T.F.D.: The Tertiary dike swarms of the Kangerdlugssuaq area, East Greenland. An example of magmatic development during continental break-up. Contrib. Mineral. Petrol. 67, 63–78 (1978)
Noe-Nygaard, A.: Tertiary igneous rocks between Shannon and Scoresby Sund, East Greenland. In: Geology of Greenland (A.E. Escher, W. S. Watt, eds.), pp. 386–404. Geol. Surv. Greenland 1976
Pankhurst, R.J., Beckinsale, R.D., Brooks, C.K.: Strontium and oxygen isotope evidence relating to the petrogenesis of the Kangerdlugssuaq alkaline intrusion, East Greenland. Contrib. Mineral. Petrol. 54, 17–42 (1976)
Shepard, S.M.F., Brown, P.E., Chambers, A.D.: The Lilloise intrusion, East Greenland: hydrogen isotope evidence for the efflux of magmatic water into the contact metamorphic aureole Contrib. Mineral. Petrol. 63, 129–148 (1977)
Soper, N.J., Higgins, A.C., Downie, C., Mathews, D.W., Brown, P.E.: Late Cretaceous — Early Tertiary Stratigraphy of the Kangerdlugssuaq area, East Greenland, and the opening of the northeast Atlantic. J. Geol. Soc. London 132, 85–102 (1976a)
Soper, N.J., Downie, C., Higgins, A.C., Costa, L.I.: Biostratigraphic ages of Tertiary basalts on the East Greenland continental margin and their relationship to plate separation in the northeast Atlantic. Earth Planet. Sci. Lett. 32, 149–157 (1976b)
Surlyk, F.: Jurassic basin evolution of East Greenland. Nature 274, 130–133 (1978)
Talwani, M., Eidholm, O.: Evolution of the Norwegian-Greenland Sea. Geol. Soc. Am. Bull. 88, 969–999 (1977)
Vogt, P.R., Avery, O.E.: Detailed magnetic surveys in the northeast Atlantic and Labrador Sea. J. Geophys. Res. 79, 363–389 (1974)
Wager, L.R.: Geological investigations in east Greenland, I, General geology from Angmagssalik to Kap Dalton. Meddr. Grønland 105, Nr. 2, 1–46 (1934)
Wager, L.R.: Geological investigations in east Greenland IV, The stratigraphy and tectonics of Knud Rasmussens land and the Kangerdlugssuaq region. Meddr. Grønland 134, Nr 5, 1–64 (1947)
Wager, L.R., Brown, G.M.: Layered igneous rocks. Edingburgh-London: Oliver and Boyd 1968
Wager, L.R., Deer, W.A.: A dyke swarm and coastal flexure in east Greenland. Geol. Mag. 75, 39–46 (1938)
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Gleadow, A.J.W., Brooks, C.K. Fission track dating, thermal histories and tectonics of igneous intrusions in East Greenland. Contr. Mineral. and Petrol. 71, 45–60 (1979). https://doi.org/10.1007/BF00371880
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DOI: https://doi.org/10.1007/BF00371880