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A late ultramafic suite in the Kap Edvard Holm layered gabbro complex, East Greenland

Published online by Cambridge University Press:  01 May 2009

Christian Tegner  and
J. Richard Wilson
Christian Tegner
Affiliation:
Geologisk Institut, Aarhus Universitet, 8000 Aarhus C, Denmark
J. Richard Wilson
Affiliation:
Geologisk Institut, Aarhus Universitet, 8000 Aarhus C, Denmark
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Abstract

The Kap Edvard Holm Complex is an early Tertiary layered gabbro situated on the western side of the Kangerdlugssuaq fjord. Layered olivine gabbros in the Taco Point area are cut by several wehrlitic sill-like bodies which comprise a late ultramafic suite. An intrusive wehrlitic facies in the inner part of the bodies consists of olivine (+minor chrome-spinel) orthocumulate with clinopyroxene oikocrysts and interstitial plagioclase, kaersutite and phlogopite. A replacive facies which occurs in the marginal zones is texturally similar to the intrusive facies but contains no chromespinel and is more feldspathic, varying from a melanocratic olivine gabbro to a feldspathic wehrlite. It occurs where the sills wedge out laterally, in the lower contact zones where finger structures are widely developed, and in the upper contact zones where wehrlitic pipes feed melanocratic sheets, called parasol structures, which preferentially follow mafic layers in the host olivine gabbro. The wehrlites formed by the intrusion of hot, hydrous, ultrabasic magma into consolidated layered olivine gabbro. The replacive facies was formed by the volume for volume metasomatic replacement of olivine gabbro; dissolution of plagioclase was accompanied by crystallization of olivine. Some clinopyroxene was initially resorbed and later reprecipitated during this process. The relatively dense pore magma migrating upwards was restricted to pipes and spread out laterally when it encountered readily replaced mafic layers, while below the sills gabbro was replaced en masse and finger structures were formed. Similar late ultramafic suites occur in ophiolites, and their presence in the Kap Edvard Holm Complex supports suggestions that it acted as an ocean ridge type magma chamber during the initiation of early Tertiary sea floor spreading in the North Atlantic.

Type
Articles
Information
Geological Magazine , Volume 130 , Issue 4 , July 1993 , pp. 431 - 442
Copyright
Copyright © Cambridge University Press 1993

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References

Barnes, S. J. 1986. The effect of trapped liquid crystallization on cumulus mineral compositions in layered intrusions Contributions to Mineralogy and Petrology 93, 524–31.CrossRefGoogle Scholar
Bedard, J. H., Sparks, R. S. J., Renner, R., Cheadle, M. J. & Hallworth, M. A. 1988. Peridotite sills and metasomatic gabbros in the Eastern Layered Series of the Rhum Complex Journal of the Geological Society, London 145, 207–24.CrossRefGoogle Scholar
Bedard, J. H. 1991. Cumulate recycling and crustal evolution in the Bay of Island ophiolite Journal of Geology 99, 225–49.CrossRefGoogle Scholar
Benn, K. & Laurent, R. 1987. Intrusive suite documented in the Troodos ophiolite plutonic complex, Cyprus Geology 15, 821–4.2.0.CO;2>CrossRefGoogle Scholar
Benn, K., Nicolas, A. & Reuber, I. 1988. Mantle-crust transition zone and origin of wehrlitic magmas: Evidence from the Oman ophiolite Tectonophysics 151, 75–85.CrossRefGoogle Scholar
Bennett, M. C., Emblin, S. R., Robins, B. & Yeo, W. J. A. 1986. High-temperature ultramafic complexes in the North Norwegian Caledonides: I – Regional setting and field relationships Norges geologiske undersokelse Bulletin 405, 1–40.Google Scholar
Bernstein, S., Rosing, M. T., Brooks, C. K. & Bird, D. K. 1992. An ocean-ridge type magma-chamber at a passive volcanic, continental margin-The Kap Edvard Holm Layered Gabbro Complex, East Greenland Geological Magazine 129, 437–56.CrossRefGoogle Scholar
Brooks, C. K. & Nielsen, T. F. D. 1982. The Phanerozoic development of the Kangerdlugssuaq area, East Green-land Meddelelser om Gronland 9, 3–30.Google Scholar
Brooks, C. K., Larsen, L. M. & Nielsen, T. F. D. 1991. Importance of iron-rich tholeiitic magmas at divergent plate margins: A reappraisal Geology 19, 269–72.2.3.CO;2>CrossRefGoogle Scholar
Butcher, A. R., Young, I. M. & Faithfull, J. W. 1985. Finger structures in the Rhum Complex Geological Magazine 122, 491–502.CrossRefGoogle Scholar
Cameron, E. N. & Desborough, G. A. 1964. Origin of certain magnetite-bearing pegmatites in the eastern part of the Bushveld Complex, South Africa Economic Geology 59, 197–225.CrossRefGoogle Scholar
Claydon, R. V. & Bell, B. R. 1992. The structure and petrology of ultrabasic rocks in the southern part of the Cuillin Igneous Complex, Isle of Skye Transactions of the Royal Society of Edinburgh, Earth Sciences 83, 635–53.CrossRefGoogle Scholar
Ernewein, M., Pflumio, C. & Whitechurch, H. 1988. The death of an accretion zone as evidenced by the magmatic history of the Sumail ophiolite, Oman Tectonophysics 151, 247–74.CrossRefGoogle Scholar
Hess, H. H. 1960. Stillwater igneous complex, Montana: a quantitative mineralogical study. Geological Society of America Memoir 80, 230 pp.Google Scholar
Huppert, H. E. & Sparks, R. S. J. 1980. The fluid dynamics of a basaltic magma chamber, replenished by an influx of hot, dense, ultrabasic magma Contributions to Mineralogy and Petrology 75, 279–89.CrossRefGoogle Scholar
Irvine, T. N. 1974. Petrology of the Duke Island Ultramafic Complex, Southeastern Alaska. Geological Society of America Memoir 138, 240 pp.Google Scholar
Irvine, T. N. 1980. Magmatic infiltration metasomatism, double-diffusive fractional crystallization, and adcumulus growth in the Muskox intrusion and other layered intrusions. In Physics of Magmatic Processes (ed. Hargraves, R. B.), pp. 325–83. Princeton: New York.CrossRefGoogle Scholar
Irvine, T. N. 1982. Terminology for layered intrusions Journal of Petrology 23, 127–62.CrossRefGoogle Scholar
Irvine, T. N. 1987. Layering and related structures in the Duke Island and Skaergaard intrusions: similarities, differences and origins. In Origins of Igneous Layering (ed. Parsons, I.), pp. 185–245. Reidel.CrossRefGoogle Scholar
Juteau, T., Ernewein, M., Reuber, I., Whitechurch, H. & Dahl, R. 1988 a. Duality of magmatism in the plutonic sequence of the Sumail Nappe, Oman Tectonophysics 151, 107–35.CrossRefGoogle Scholar
Juteau, T., Beurrier, M., Dahl, R. & Nehlig, P. 1988 b. Segmentation at a fossil spreading axis: The plutonic sequence of the Wadi Haymiliyah area (Haylayn Block, Sumail Nappe, Oman) Tectonophysics 151, 167–97.CrossRefGoogle Scholar
Kerr, R. C. & Tait, S. R. 1985. Convective exchange between pore fluid and an overlying reservoir of denser fluid: a post-cumulus process in layered intrusions Earth and Planetary Science Letters 75, 147–56.CrossRefGoogle Scholar
Kruger, F. J. & Marsh, J. S. 1985. The mineralogy, petrology, and origin of the Merensky Cyclic Unit in the Western Bushveld Complex Economic Geology 80, 958–74.CrossRefGoogle Scholar
Larsen, L. M. & Watt, W. S. 1985. Episodic volcanism during break-up of the North Atlantic: evidence from East Greenland plateau basalts Earth and Planetary Science Letters 73, 105–16.CrossRefGoogle Scholar
McBirney, A. R. & Sonnenthal, E. L. 1990. Metasomatic replacement in the Skaergaard intrusion, East Green-land: preliminary observations Chemical Geology 88, 245–60.CrossRefGoogle Scholar
Morse, S. A., Owens, B. E. & Butcher, A. R. 1987. Origin of finger structures in the Rhum Complex: phase equilibrium and heat effects Geological Magazine 124, 205–10.CrossRefGoogle Scholar
Nicolas, A. 1989. Structures of Ophiolite and Dynamics of Oceanic Lithosphere. Kluwer Academic Publications. 320 pp.CrossRefGoogle Scholar
Nicholson, D. M. & Matihez, E. A. 1991. Petrogenesis of the Merensky Reef in the Rustenburg section of the Bushveld Complex Contributions to Mineralogy and Petrology 107, 293–309.CrossRefGoogle Scholar
Raedeke, L. D. & McCallum, I. S. 1984. Investigations in the Stillwater Complex: Part II. Petrology and Petrogenesis of the Ultramafic Series Journal of Petrology 25, 395–420.CrossRefGoogle Scholar
Robins, B. 1982. Finger structures in the Lille Kuford layered intrusion, Finmark, Northern Norway Contributions to Mineralogy and Petrology 81, 290–5.CrossRefGoogle Scholar
Robins, B., Haukvik, L. & Jansen, S. 1987. The organization and internal structure of cyclic units in the Honningsvåg Intrusive Suite, North Norway: Implications for intrusive mechanism, double-diffusive convection and pore-magma infiltration. In Origins of Igenous Layering (ed. Parsons, I.), pp. 287–312. Reidel.CrossRefGoogle Scholar
Schiffries, C. M. 1982. The petrogenesis of a platiniferous dunite pipe in the Bushveld Complex: Infiltration metasomatism by a chloride solution Economic Geology 77, 1439–53.CrossRefGoogle Scholar
Tait, R. S. 1985. Fluid dynamic and geochemical evolution of cyclic unit 10, Rhum, Eastern Layered Series Geological Magazine 122, 469–84.CrossRefGoogle Scholar
Tegner, C., Wilson, J. R. & Brooks, C. K. in press. Intraplutonic quench zones in the Kap Edvard Holm layered gabbro complex, East Greenland. Journal of PetrologyGoogle Scholar
Viljoen, M. J. & Scoon, R. N. 1985. The distribution and main geologic features of discordant bodies of iron-rich ultramafic pegmatite in the Bushveld Complex Economic Geology 80, 1109–28.CrossRefGoogle Scholar
Yoder, H. S. 1965. Diopside-anorthite-water at five and ten kilobars and its bearing on explosive volcanism Carnegie Institute of Washington Yearbook 64, 82–9.Google Scholar