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The Unit 12 allivalite, Eastern Layered Intrusion, Isle of Rum: a textural and geochemical study of an open-system magma chamber

Published online by Cambridge University Press:  12 November 2008

MARIAN B. HOLNESS  and
BEN WINPENNY
MARIAN B. HOLNESS*
Affiliation:
Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK
BEN WINPENNY
Affiliation:
Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK
*
*Author for correspondence: [email protected]
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Abstract

The Eastern Layered Intrusion of the Rum Central Complex, NW Scotland, comprises 16 macro-units broadly defined by a basal peridotite body overlain by gabbros and troctolites. The local term for the upper plagioclase-bearing cumulates is ‘allivalite’. The Unit 12 allivalite contains five subsidiary peridotite horizons, each continuous on the kilometre scale. Field, textural and geochemical evidence points to the Unit 12 allivalite forming by progressive accumulation of crystals from up to seven separate magma batches, varying from picrite to basalt. The thickness of the magma lens in the sill-like chamber was as low as 30 m during a significant part of the development of the Unit 12 allivalite, and evidence supports one eruption from the chamber during its accumulation.

Keywords

Rumlayered intrusioncumulatetexturetroctolite
Type
Original Article
Information
Geological Magazine , Volume 146 , Issue 3 , May 2009 , pp. 437 - 450
Copyright
Copyright © Cambridge University Press 2008

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References

Asimow, P. D. & Ghiorso, M. S. 1998. Algorithmic modifications extending MELTS to calculate subsolidus phase relations. American Mineralogist 83, 1127–31.CrossRefGoogle Scholar
Bédard, 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
Brown, G. M. 1956. The layered ultrabasic rocks of Rhum, Inner Hebrides. Philosophical Transactions of the Royal Society of London, Series B 240, 1–54.Google Scholar
Butcher, A. R. 1985. Channelled metasomatism in Rhum layered cumulates – evidence from late-stage veins. Geological Magazine 122, 503–18.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
Dunham, A. C. & Wadsworth, W. J. 1978. Cryptic variation in the Rhum layered intrusion. Mineralogical Magazine 42, 347–56.CrossRefGoogle Scholar
Elliott, M. T., Cheadle, M. J. & Jerram, D. A. 1997. On the identification of textural equilibrium in rocks using dihedral angle measurements. Geology 25, 355–8.2.3.CO;2>CrossRefGoogle Scholar
Emeleus, C. H. 1994. 1:20 000 solid geology map of Rum. 2nd edn. Edinburgh: Scottish Natural Heritage.Google Scholar
Emeleus, C. H., Cheadle, M. J., Hunter, R. H., Upton, B. G. J. & Wadsworth, W. J. 1996. The Rum Layered Suite. In Layered Intrusions (ed. Cawthorn, R. G.), pp. 403–39. Developments in Petrology, vol. 15. The Netherlands: Elsevier.CrossRefGoogle Scholar
Faithfull, J. W. 1985. The Lower Eastern Layered Series of Rhum. Geological Magazine 122, 459–68.CrossRefGoogle Scholar
Ghiorso, M. S. & Sack, R. O. 1995. Chemical mass transfer in magmatic processes. IV. A revised and internally consistent thermodynamic model for the interpolation and extrapolation of liquid-solid equilibria in magmatic systems at elevated temperatures and pressures. Contributions to Mineralogy and Petrology 119, 197–212.CrossRefGoogle Scholar
Harker, A. 1908. The geology of the Small Isles of Inverness-shire. Memoirs of the Geological Survey of Scotland, Sheet 60, 210 pp.Google Scholar
Holness, M. B. 1999. Contact metamorphism and anatexis of Torridonian arkose by minor intrusions of the Rum Igneous Complex, Inner Hebrides, Scotland. Geological Magazine 136, 527–42.CrossRefGoogle Scholar
Holness, M. B. 2005. Spatial constraints on magma chamber replenishment events from textural observations of cumulates: the Rum Layered Intrusion, Scotland. Journal of Petrology 46, 1585–1601.CrossRefGoogle Scholar
Holness, M. B. 2007. Textural immaturity of cumulates as an indicator of magma chamber processes: infiltration and crystal accumulation in the Rum Layered Suite. Journal of the Geological Society, London 164, 529–39.CrossRefGoogle Scholar
Holness, M. B., Cheadle, M. J. & McKenzie, D. 2005. On the use of changes in dihedral angle to decode late-stage textural evolution in cumulates. Journal of Petrology 46, 1565–83.CrossRefGoogle Scholar
Holness, M. B., Hallworth, M. A., Woods, A. & Sides, R. E. 2007. Infiltration metasomatism of cumulates by intrusive magma replenishment: the Wavy Horizon, Isle of Rum, Scotland. Journal of Petrology 48, 563–87.CrossRefGoogle Scholar
Holness, M. B., Nielsen, T. F. N. & Tegner, C. 2007. Textural maturity of cumulates: a record of chamber filling, liquidus assemblage, cooling rate and large-scale convection in mafic layered intrusions. Journal of Petrology 48, 141–57.CrossRefGoogle Scholar
Huppert, H. E. & Sparks, R. S. J. 1980. The fluid dynamics of a basaltic magma chamber replenished by influx of hot, dense ultramafic magma. Contributions to Mineralogy and Petrology 75, 279–89.CrossRefGoogle Scholar
Irvine, T. N. 1987. Appendix 1: Glossary of terms for layered intrusions. In Origins of Igneous Layering (ed. Parsons, I.), pp. 641–7. Dordrecht, Holland: D. Reidel Publishing Company.CrossRefGoogle Scholar
Kushiro, I. 1972. Effects of water on the composition of magmas formed at high pressures. Journal of Petrology 13, 311–34.CrossRefGoogle Scholar
Maaløe, S. 1978. The origin of rhythmic layering. Mineralogical Magazine 42, 337–45.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
O'Driscoll, B., Donaldson, C. H., Troll, V. R., Jerram, D. A. & Emeleus, C. H. 2007 a. An origin for harrisitic and granular olivine in the Rum Layered Suite, NW Scotland: a crystal size distribution study. Journal of Petrology 48, 253–70.CrossRefGoogle Scholar
O'Driscoll, B., Hargraves, R. B., Emeleus, C. H., Troll, V., Donaldson, C. H. & Reavy, R. J. 2007 b. Magmatic lineations inferred from anisotropy of magnetic susceptibility fabrics in units 8, 9 and 10 of the Rum Eastern Layered Series, NW Scotland. Lithos 98, 27–44.CrossRefGoogle Scholar
Palacz, Z. A. 1985. Sr–Nd–Pb isotopic evidence for crustal contamination in the Rhum intrusion. Earth and Planetary Science Letters 74, 35–44.CrossRefGoogle Scholar
Renner, R. & Palacz, Z. 1987. Basaltic replenishment of the Rhum magma chamber: evidence from unit 14. Journal of the Geological Society, London 144, 961–70.CrossRefGoogle Scholar
Rosenberg, C. L. & Riller, U. 2000. Partial melt topology in statically and dynamically recrystallized granite. Geology 28, 7–10.2.0.CO;2>CrossRefGoogle Scholar
Tait, S. R. 1985. Fluid dynamic and geochemical evolution of cyclic unit 10, Rhum, Eastern Layered Series. Geological Magazine 122, 469–84.CrossRefGoogle Scholar
Tepley, F. J. III & Davidson, J. P. 2003. Mineral-scale Sr-isotope constraints on magma evolution and chamber dynamics in the Rum layered intrusion, Scotland. Contributions to Mineralogy and Petrology 145, 628–41.CrossRefGoogle Scholar
Upton, B. G. J., Skovgaard, A. C., McClurg, J., Kirstein, L., Cheadle, M., Emeleus, C. H., Wadsworth, W. J. & Fallick, A. E. 2002. Picritic magmas and the Rum ultramafic complex, Scotland. Geological Magazine 139, 437–52.CrossRefGoogle Scholar
Vernon, R. H. 1968. Microstructures of high-grade metamorphic rocks at Broken Hill, Australia. Journal of Petrology 9, 1–22.CrossRefGoogle Scholar
Volker, J. A. & Upton, B. G. J. 1990. The structure and petrogenesis of the Trallval and Ruinsival areas of the Rhum ultrabasic complex. Transactions of the Royal Society of Edinburgh: Earth Sciences 81, 69–88.CrossRefGoogle Scholar
Wager, L. R. & Deer, W. A. 1939. Geological investigations in East Greenland: Part III – The petrology of the Skaergaard Intrusion, Kangerdlugssuaq. Meddelelser om Grønland 105, 1–323.Google Scholar
Yoder, H. S. Jr. 1973. Contemporaneous basaltic and rhyolitic magmas. American Mineralogist 58, 153–71.Google Scholar
Young, I. M., Greenwood, R. C. & Donaldson, C. H. 1988. Formation of the Eastern Layered Series of the Rhum Complex, northwest Scotland. Canadian Mineralogist 26, 225–33.Google Scholar
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