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The minor intrusions of Assynt, NW Scotland: early development of magmatism along the Caledonian Front

  • K. M. Goodenough (a1), B. N. Young (a2) (a3) and I. Parsons (a4)

Abstract

The Assynt Culmination of the Moine Thrust Belt, in the northwest Scottish Highlands, contains a variety of Caledonian alkaline and calc-alkaline intrusions that are mostly of Silurian age. These include a significant but little-studied suite of dykes and sills, the Northwest Highlands Minor Intrusion Suite. We describe the structural relationships of these minor intrusions and suggest a classification into seven swarms. The majority of the minor intrusions can be shown to pre-date movement in the Moine Thrust Belt, but some appear to have been intruded during the period of thrusting. A complex history of magmatism is thus recorded within this part of the Moine Thrust Belt. New geochemical data provide evidence of a subduction-related component in the mantle source of the minor intrusions.

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Corresponding author

* E-mail: kmgo@bgs.ac.uk

References

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Atherton, M.P. and Ghani, A.A. (2002) Slab breakoff: a model for Caledonian, Late Granite syn-collisional magmatism in the orthotectonic (metamorphic) zone of Scotland and Donegal, Ireland. Lithos, 62, 65–85.
Bailey, E.B. (1935) The Glencoul Nappe and the Assynt Culmination. Geological Magazine, 72, 151–165.
Beccaluva, L., Coltorti, M., Di Girolamo, P., Melluso, L., Milani, L., Morra, V. and Siena, F. (2002) Petrogenesis and evolution of Mt. Vulture alkaline volcanism (Southern Italy). Mineralogy and Petrology, 74, 277–297.
Bonney, T.G. (1883) Notes on a series of rocks from the North-West Highlands collected by C. Callaway, Esq. Quarterly Journal of the Geological Society, 39, 414–422.
Canning, J.C., Henney, P.J., Morrison, M.A., van Calsteren, P.W.C, Gaskarth, J.W. and Swarbrick, A. (1998) The Great Glen Fault: a major vertical lithospheric boundary. Journal of the Geological Society, 155, 425–428.
Coward, M.P. (1983) The thrust and shear zones of the Moine Thrust zone and the NW Scottish Caledonides. Journal of the Geological Society, 140, 795–811.
Coward, M.P. (1985) The thrust structures of southern Assynt, Moine thrust zone. Geological Magazine, 122, 596–607.
Coward, M.P. and Potts, G.J. (1985) Fold nappes: examples from the Moine Thrust zone. Pp. 1147–1158 in: The Caledonide Orogen – Scandinavia and Related Areas (Gee, D.G. and Sturt, B.A., editors). John Wiley & Sons Ltd., Chichester, UK.
Elliott, D. and Johnson, M.R.W. (1980) Structural evolution in the northern part of the Moine thrust belt, NW Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences, 71, 69–96.
Fowler, M.B. and Henney, P.J. (1996) Mixed Caledonian appinite magmas: implications for lamprophyre fractionation and high Ba-Sr granite genesis. Contributions to Mineralogy and Petrology, 126, 199–215.
Gertisser, R. and Keller, J. (2003) Trace element and Nd, Sr, Pb and O isotope variations in medium-K and high-K volcanic rocks from Merapi Volcano, Central Java, Indonesia: Evidence for the involvement of subducted sediments in Sunda Arc magma genesis. Journal of Petrology, 44, 457–489.
Gillespie, M.R. and Styles, M.T. (1999) BGS Rock Classification Scheme Volume 1. Classification of Igneous Rocks. BritishGeological Survey Research report (2nd edition), RR 99-06. Available at the BGS website http://www.bgs.ac.uk/bgsrcs/
Halliday, A.N., Aftalion, M., Parsons, I., Dickin, A.P and Johnson, M.R.W. (1987) Syn-orogenic alkaline magmatism and its relationship to the Moine Thrust Zone and the thermal state of the lithosphere in NW Scotland. Journal of the Geological Society, 144, 611–617.
Heddle, M.F. (1881) The geognosy and mineralogy of Scotland. Sutherland – Continued. Mineralogical Magazine, 4, 197–254.
Horne, J. and Teall, J.J.H. (1892) On borolanite – an igneous rock intrusive in the Cambrian limestone of Assynt, Sutherlandshire, and the Torridon sandstone of Ross-shire. Transactions of the Royal Society of Edinburgh, 37, 163–178.
Irvine, T.N. and Baragar, W.R.A. (1971) A guide to the chemical classification of the common volcanic rocks. Canadian Journal of EarthSciences, 8, 523–548.
Johnson, M.R.W. and Parsons, I. (1979) Geological Excursion Guide to the Assynt District of Sutherland. Edinburgh Geological Society, Edinburgh.
Krabbendam, M. and Leslie, A.G. (2004) Lateral ramps and thrust terminations: an example from the Moine Thrust Zone, NW Scotland. Journal of the Geological Society, 161, in press.
Le Bas, M.J., Le Maitre, R.W., Streckeisen, A. and Zanettin, B. (1986) A chemical classification of volcanic rocks based on the total alkali-silica diagram. Journal of Petrology, 27, 745–750.
Le Maitre, R.W. and 11 others (1989) A Classification of Igneous Rocks and Glossary of Terms. Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks. Blackwell Scientific Publications, Oxford.
McDonough, W.F. and Sun, S.-S. (1995) The composition of the Earth. Chemical Geology, 120, 223–255.
Oliver, G.J.H. (2002) Chronology and terrane assembly, new and old controversies. Pp. 201–212 in: The Geology of Scotland (Trewin, N.H., editor). The Geological Society, London.
Park, R.G, Stewart, A.D. and Wright, D.T. (2002) The Hebridean terrane. Pp 45–80 in: The Geology of Scotland (Trewin, N.H., editor).The Geological Society, London.
Parsons, I. (1965) The feldspathic syenites of the Loch Ailsh intrusion, Assynt, Scotland. Journal of Petrology, 6, 365–394.
Parsons, I. (1979) The Assynt alkaline suite. Pp. 677–681 in: BritishCaledonides Reviewed (Harris, A.L., Holland, C.H., Leake, B.E., editors). Geological Society of London.
Parsons, I. (1999) Late Ordovician to mid-Silurian alkaline intrusions of the North-west Highlands of Scotland. Pp. 347–393 in: Caledonian Igneous Rocks of Great Britain. (Stephenson, D., Bevins, R.E., Millward, D., Highton, A.J., Parsons, I., Stone, P. and Wadsworth, W.J., editors). Geological Conservation Review Series, No. 17. Joint Nature Conservation Committee, Peterborough, UK.
Parsons, I. and McKirdy, A.P. (1983) Inter-relationship of igneous activity and thrusting in Assynt: excavations at Loch Borralan. ScottishJournal of Geology, 19, 59–66.
Peach, B.N., Horne, J., Gunn, W., Clough, C.T., Hinxman, L.W. and Teall, J.J.H. (1907) The geological structure of the North-West Highlands of Scotland. Memoir of the Geological Survey of the United Kingdom.
Phemister, J. (1926) The alkaline igneous rocks of the Loch Ailsh district. In: The Geology of Strath Oykell and Lower Lochsh in (Read, H.H., Phemister, J. and Ross, G., editors). Memoir of the Geological Survey of Great Britain, Sheet 102 (Scotland).
Sabine, P.A. (1952) The ledmorite dyke of Achmelvich, near Lochinver, Sutherland. Mineralogical Magazine, 29, 827–832.
Sabine, P.A. (1953) The petrography and geological significance of the post-Cambrian minor intrusions of Assynt and the adjoiningdistricts of north-west Scotland. Quarterly Journal of the Geological Society, 109, 137–171.
Shand, S.J. (1910) On borolanite and its associates in Assynt. Transactions of the Edinburgh Geological Society, 9, part III, 202–215.
Stormer, J.C. and Nicholls, J. (1978) XLFRAC: A program for the interactive testing of magmatic differentiation models. Computers and Geoscience, 4, 143–159.
Strachan, R.A., Smith, M., Harris, A.L. and Fettes, D.J. (2002) The Northern Highland and Grampian terranes. Pp. 81–148 in: The Geology of Scotland (Trewin, N.H., editor). The Geological Society, London.
Sun, S.-S. and McDonough, W.F. (1989) Chemical and isotopic systematics of oceanic basalts: implications for mantle compositions and processes. P. 313–347 in: Magmatism in the Ocean Basins (Saunders, A.D. and Norry, M.J., editors). Special Publication No. 42, Geological Society of London.
Teall, J.J.H. (1900) On nepheline-syenite and its associates in the North-west of Scotland. Geological Magazine, 7, 385–392.
Teall, J.J.H. (1907) Post-Cambrian igneous rocks of older date than the great thrust-movements of the region: their petrography. Pp. 440–452 in: The Geological Structure of the North-West Highlands of Scotland (Peach, B.N., Horne, J., Gunn, W., Clough, C.T., Hinxman, L.W. and Teall, J.J.H., editors). Memoir of the Geological Survey of the United Kingdom.
Thirlwall, M.F. and Burnard, P. (1990) Pb-Sr-Nd isotope and chemical study of the origin of undersaturated and oversaturated shoshonitic magmas from the Borralan pluton, Assynt, NW Scotland. Journal of the Geological Society, 147, 259–269.
Thompson, R.N. and Fowler, M.B. (1986) Subductionrelated shoshonitic and ultrapotassic magmatism: a study of Siluro-Ordovician syenites from the Scottish Caledonides. Contributions to Mineralogy and Petrology, 94, 507–522.
Van Breemen, O., Aftalion, M. and Johnson, M.R.W. (1979) Age of the Loch Borrolan Complex, Assynt, and late movements alongthe Moine Thrust Zone. Journal of the Geological Society, 136, 489–495.
Woolley, A.R. (1970) The structural relationships of the Loch Borrolan Complex, Scotland. Geological Journal, 7, 171–182.
Young, B.N. (1989) The petrology and petrogenesis of a suite of minor alkaline intrusions in the Assynt District, Sutherland. Unpublished PhD thesis, University of Aberdeen.
Young, B.N., Parsons, I. and Threadgould, R. (1994) Carbonatite near the Loch Borralan intrusion, Assynt. Journal of the Geological Society, 151, 945–954.

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The minor intrusions of Assynt, NW Scotland: early development of magmatism along the Caledonian Front

  • K. M. Goodenough (a1), B. N. Young (a2) (a3) and I. Parsons (a4)

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