Hostname: page-component-586b7cd67f-t7czq Total loading time: 0 Render date: 2024-11-22T14:51:46.376Z Has data issue: false hasContentIssue false
  • English
  • Français

The structure and petrology of ultrabasic rocks in the southern part of the Cuillin Igneous Complex, Isle of Skye

Published online by Cambridge University Press:  03 November 2011

R. V. Claydon  and
B. R. Bell
R. V. Claydon
Affiliation:
Department of Geology and Applied Geology, University of Glasgow, Lilybank Gardens, Glasgow G12 8QQ, Scotland.
B. R. Bell*
Affiliation:
Department of Geology and Applied Geology, University of Glasgow, Lilybank Gardens, Glasgow G12 8QQ, Scotland.
*
* To whom correspondence should be addressed.
Get access Rights & Permissions [Opens in a new window]

Abstract

The ultrabasic rocks of the southern portion of the Early Tertiary Cuillin Igneous Complex, Isle of Skye, are recognised as forming a Peridotite Series s.l. and have been separated into six distinct structural–lithological units. These units range from almost pure dunite (Unit 1, at the lowest structural level), through to feldspathic peridotites and allivalites (Units 5 and 6, at the highest structural levels). Detailed field and mineralogical studies indicate that both cumulus and postcumulus processes involving ultrabasic (picritic) magmas may be identified, and that the latter processes have significantly modified many of the primary features of these rocks.

Layering, both modal and phase, is present within all six units, although it is more prominent within the higher units, especially Units 5 and 6. Differing orientations of fabrics defined by cumulus spinel and intercumulus plagioclase layers within Unit 3 indicate the important role of compaction and intercumulus melt migration. Unit 4 is extremely heterogeneous, involving material ranging in composition from peridotite to allivalite, and provides clear evidence for postcumulus melt movement, magma-mixing, disruption and brecciation. Units 5 and 6 developed with a more porous cumulus framework, giving rise to dendritic growths involving cumulus olivine and poikilitic plagioclase.

It is concluded that postcumulus melt movement, injection and magma-mixing, involving ultrabasic magmas, were significant processes in the formation of the ultrabasic rocks of the Cuillin Igneous Complex.

Keywords

peridotiteallivalitelayeringcumulatespostcumulushybridisationbrecciamixing.
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 83 , Issue 4 , 1992 , pp. 635 - 653
Copyright
Copyright © Royal Society of Edinburgh 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

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. J GEOL SOC LONDON 145, 207–24.CrossRefGoogle Scholar
Bell, B. R. & Claydon, R. V. 1992. The cumulus and post-cumulus evolution of chrome-spinels in ultrabasic layered intrusions: Evidence from the Cuillin Igneous Complex, Isle of Skye, Scotland. CONTRIB MINERAL PETROL (in press).Google Scholar
Bell, B. R. & Harris, J. W. 1986. An excursion guide to the geology of the Isle of Skye. Glasgow: Geological Society of Glasgow.Google Scholar
Bevan, J. C. & Hutchison, R. 1984. Layering in the Gars-bheinn ultrabasic sill, Isle of Skye: A new interpretation and its implications. SCOTT J GEOL 20, 329–41.CrossRefGoogle Scholar
Bowen, N. L. 1928. The evolution of the igneous rocks. Princeton, N.J.: Princeton University Press.Google Scholar
Brown, G. M. 1956. The layered ultrabasic rocks of Rhum, Inner Hebrides. PHILOS TRANS R SOC LONDON B240, 1–53.Google Scholar
Butcher, A. R. 1985. Channelled metasomatism in Rhum layered cumulates-evidence from late-stage veins. GEOL MAG 122, 503–18.CrossRefGoogle Scholar
Butcher, A. R., Young, I. M. & Faithfull, J. W. 1985. Finger structures in the Rhum Complex. GEOL MAG 122, 491–502.CrossRefGoogle Scholar
Claydon, R. V. 1990. A petrological study of mafic hypabyssal and ultramafic plutonie rocks of the Cuillin Igneous Complex, Isle of Skye, Scotland. Ph.D. Thesis, University of Glasgow.Google Scholar
Donaldson, C. H. 1975. Ultrabasic breccias in layered intrusions. The Rhum Complex. J GEOL 83, 33–45.CrossRefGoogle Scholar
Donaldson, C. H. 1977. Petrology of anorthite-bearing gabbroic anorthosite dykes in northwest Skye. J PETROL 18, 595–620.CrossRefGoogle Scholar
Donaldson, C. H. 1982a. Origin of some of the Rhum harrisites by segregation of intercumulus liquid. MINER MAG 45, 201–9.CrossRefGoogle Scholar
Donaldson, C. H. 1982b. Spinifex-textures komatiites: a review of textures, compositions and layering. In Arndt, N. T. & Nisbet, E. G. (Eds.) Komatiites, 213–44. London: George Allen & Unwin.Google Scholar
Donaldson, C. H., Drever, H. I. & Johnston, R. 1973. Crystallisation of poikilo-macrospherulitic feldspar in a Rhum peridotite. NATURE 243, 69–70.Google Scholar
Drever, H. I. & Johnston, R. 1958. The petrology of picritic rocks in minor intrusions—a Hebridean Group. TRANS ROY SOC EDINBURGH 63, 459–99.CrossRefGoogle Scholar
Drever, H. I. & Johnston, R. 1966. A natural high-lime liquid more basic than basalt. J PETROL 7, 414–20.CrossRefGoogle Scholar
Emeleus, C. H. 1987. The Rhum Layered Complex. In Parsons, I. (Ed.) Origins of layering in igneous rocks, 263–86. Dordrecht: D. Reidel.CrossRefGoogle Scholar
Finger, L. W. 1972. The uncertainty in the calculated ferric iron content of a microprobe analysis. CAR INST YBOOK 71, 600–03.Google Scholar
Geikie, A. & Teall, J. J. H. 1984. On the banded structure of some Tertiary gabbros in the Isle of Skye. Q J GEOL SOC LONDON 50, 645–60.CrossRefGoogle Scholar
Gibb, F. G. F. 1965. The age relationships between the Sgurr Dubh ultrabasic laccolite and Cuillin gabbros. SCOTT J GEOL 1, 300–03.CrossRefGoogle Scholar
Gibb, F. G. F. 1968. Flow differentiation in the xenolithic ultrabasic dykes of the Cuillins and the Strathaird Peninsula, Isle of Skye, Scotland J. PETROL 9, 411–43.CrossRefGoogle Scholar
Gibb, F. G. F. 1974. Supercooling and the crystallization of plagioclase from a basaltic magma. MINER MAG 39, 641–53.CrossRefGoogle Scholar
Gibb, F. G. F. 1976. Ultrabasic rocks of Rhum and Skye: the nature of the parent magma. J GEOL SOC LONDON 132, 209–22.CrossRefGoogle Scholar
Greenwood, R. C, Donaldson, C. H. & Emeleus, C. H. 1990. The contact zone of the Rhum ultrabasic intrusion: evidence of peridotite formation from magnesian magmas. J GEOL SOC LONDON 147, 209–12.CrossRefGoogle Scholar
Harker, A. 1904. The Tertiary Igneous Rocks of Skye. MEM GEOL SURV SCOTLAND.CrossRefGoogle Scholar
Harker, A. 1908. The Geology of the Small Isles of Inverness-shire. MEM GEOL SURV SCOTLAND.Google Scholar
Hunter, R. H. 1987. Textural equilibration in layered igneous rocks. In Parsons, I. (Ed.) Origins of layering in igneous rocks, 473–503. Dordrecht: D. Reidel.CrossRefGoogle Scholar
Hutchison, R. 1964. The Tertiary basic rocks of the Western Cuillin, Isle of Skye. Ph.D. Thesis, University of Glasgow.Google Scholar
Hutchison, R. 1966. The age relationships between the Sgurr Dubh ultrabasic laccolite and Cuillin gabbros. SCOTT J GEOL 2, 227–8.CrossRefGoogle Scholar
Hutchison, R. 1968. Origin of the White Allivalite, Western Cuillin, Isle of Skye. GEOL MAG 105, 338–47.CrossRefGoogle Scholar
Hutchison, R. & Bevan, J. C. 1977. The Cuillin Layered Igneous Complex—Evidence for multiple intrusion and former presence of a picritic liquid. SCOTT J GEOL 13, 197–210.CrossRefGoogle Scholar
Irvine, T. N. 1979. Rocks whose composition is determined by crystal accumulation and sorting. In Yoder, H. S. (Ed.) The evolution of the igneous rocks, Fiftieth Anniversary Perspectives, 245–306. Princeton N.J.: Princeton University Press.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 Hargraves, R. B. (Ed.) Physics of magmatic processes, 325–83. Princeton, N.J.: Princeton University Press.CrossRefGoogle Scholar
Irvine, T. N. 1982. Terminology for layered intrusion. J PETROL 23, 127–62.CrossRefGoogle Scholar
Irvine, T. N. 1987. Processes involved in the formation and development of layered igneous rocks. In Parsons, I. (Ed.) Origins of layering in igneous rocks, 649–56. Dordrecht: D. Reidel.Google Scholar
Kushiro, I. 1979. Fractional crystallisation of basaltic magma. In Yoder, H. S. (Ed.) The evolution of the igneous rocks, Fiftieth Anniversary Perspectives, 171–203. Princeton, N.J.: Princeton University Press.Google Scholar
Marshall, L. A. & Sparks, R. S. J. 1984. Origin of some mixed-magma and net-veined ring intrusions. J GEOL SOC LONDON 141, 171–182.CrossRefGoogle Scholar
McBirney, A. R. 1984. Igneous petrology. San Francisco: Freeman, Cooper.Google Scholar
McBirney, A. R. & Noyes, R. M. 1979. Crystallization and layering in the Skaergaard Intrusion. J PETROL 20, 487–554.CrossRefGoogle Scholar
Morse, S. A. 1980. Basalts and phase diagrams. New York: Springer-Verlag.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. GEOL MAG 124, 205–10.CrossRefGoogle Scholar
Osborn, E. F. 1979. The reaction principle. In Yoder, H. S. (Ed.) The evolution of the igneous rocks, Fiftieth Anniversary Perspectives, 133–69. Princeton, N.J.: Princeton University Press.Google Scholar
Parsons, I. 1987. The origins of layering in igneous rocks. Dordrecht: D. Reidel.CrossRefGoogle Scholar
Roeder, P. L., Campbell, I. H. & Jamieson, H. E. 1979. A re-evaluation of the olivine-spinel geothermometer. CONTRIB MINERAL PETROL 68, 324–34.CrossRefGoogle Scholar
Robins, B. 1982. Finger structures in the Lille Kufjord Layered Intrusion, Finnmark, Northern Norway. CONTRIB MINERAL PETROL 81, 290–5.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. TRANS ROY SOC EDINBURGH: EARTH SCI 81, 69–88.CrossRefGoogle Scholar
Wadsworth, W. J. 1961. The layered ultrabasic rocks of south-west Rhum, Inner Hebrides. PHILOS TRANS R SOC LONDON B244, 21–64.Google Scholar
Wager, L. R. & Brown, G. M. 1968. Layered igneous rocks. Edinburgh: Oliver & Boyd.Google Scholar
Wager, L. R., Brown, G. M. & Wadsworth, W. J. 1960. Types of igneous cumulates. J PETROL 1, 73–85.CrossRefGoogle Scholar
Weedon, D. S. 1961. Basic igneous rocks of the Southern Cuillin, Isle of Skye. TRANS GEOL SOC GLASGOW 24, 190–212.CrossRefGoogle Scholar
Weedon, D. S. 1965. The layered ultrabasic rocks of Sgurr Dubh, Isle of skye. SCOTT J GEOL 1, 41–68.CrossRefGoogle Scholar
Young, I. M. 1984. Mixing of supernatant and interstitial fluids in the Rhum Layered Intrusion. MINER MAG 48, 345–50.CrossRefGoogle Scholar
Young, I. M. & Donaldson, C. H. 1985. Formation of granular-textured layers and laminae within the Rhum crystal pile. GEOL MAG 122, 519–28.CrossRefGoogle Scholar
Zinovieff, P. 1958. The basic layered intrusion and associated igneous rocks of the central and eastern Cuillin Hills, Isle of Skye. Ph.D. Thesis, University of Oxford.Google Scholar