Hostname: page-component-cd9895bd7-mkpzs Total loading time: 0 Render date: 2024-12-18T15:18:48.808Z Has data issue: false hasContentIssue false
  • English
  • Français

Mineral chemistry of the Mull-Morvern Tertiary lava succession, western Scotland

Published online by Cambridge University Press:  05 July 2018

Andrew C. Kerr
Andrew C. Kerr*
Affiliation:
Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, UK
Get access Rights & Permissions [Opens in a new window]

Abstract

The 1800 m thick preserved remnant of the Tertiary lava succession of Mull and Morvern consists of three basic mantle-derived magma types, with compositions varying from tholeiitic to mildly alkalic, and from picritic basalts to trachytes. This results in a similarly wide range in mineral compositions. Contrary to the suggestions of previous workers the mineral chemistry of the lava succession (in conjunction with published major and trace element chemistry) is strongly supportive of a fractional crystallisation origin for the more evolved lavas.

Resorped and regrown (with more basic material) plagioclase phenocrysts found in the more-evolved are indicative of magma mixing processes involving replenishment of an evolving magma chamber with more-basic magma. Lavas containing 15–20 vol.% plagioclase phenocrysts probably represent eruptions from the top of a magma chamber where flotation cumulates of plagioclase had developed. Fragmental phenocrysts found in some highly plagioclase phyric lavas (from near the top of the preserved lava succession) suggest that the eruption of lavas may have been explosive.

Keywords

Tertiary lavasfractional crystallizationplagioclaseMull-MorvernScotland
Type
Research Article
Information
Mineralogical Magazine , Volume 62 , Issue 3 , June 1998 , pp. 295 - 312
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1998

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

Bailey, E.B., Clough, C.T., Wright, W.B., Richey, J.E. and Wilson, G.V. (1924) Tertiary and post-Tertiary geology of Mull, Loch Aline and Oban. Mem. Geol. Surv. G.B., Scotland.Google Scholar
Beckinsale, R.D., Pankhurst, R.J., Skelhorn, R.R. and Walsh, J.N. (1978) Geochemistry and petrogenesis of the Early Tertiary lava pile of the Isle of Mull, Scotland. Contrib. Mineral. Petrol., 66, 415–27.CrossRefGoogle Scholar
Bell, B.R. and Claydon, R.V. (1992) The cumulus and post-cumulus evolution of the chrome-spinels in ultrabasic layered intrusions: evidence from the Cuillin Igneous Complex, Isle of Skye, Scotland. Contrib. Mineral. Petrol., 112, 242–53.CrossRefGoogle Scholar
Bryan, W.B. (1983) Systematics of modal phenocryst assemblages in submarine basalts: Petrologic implications. Contrib. Mineral. Petrol., 83, 62–74.CrossRefGoogle Scholar
Cox, K.G. and Mitchell, C. (1988) Importance of crystal settling in the differentiation of Deccan Trap basaltic magmas. Nature, 333, 447–9.CrossRefGoogle Scholar
Deer, W.A., Howie, R.A. and Zussman, J. (1992) An Introduction to the Rock-forming Minerals; Second edition. Longman, 696 pp.Google Scholar
Dick, H.J.B. and Bullen, T. (1984) Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas. Contrib. Mineral. Petrol., 86, 54–76.CrossRefGoogle Scholar
Donaldson, C.H. (1977) Petrology of anorthite-bearing gabbroic anorthosite dykes in NW Skye. J. Petrol., 18, 595–620.CrossRefGoogle Scholar
Emeleus, C.H. (1985) Tertiary lavas and sediments of Northwest Rhum, Inner Hebrides. Geol. Mag., 122, 419–37.CrossRefGoogle Scholar
Emeleus, C.H., Allwright, E.A., Kerr, A.C. and Williamson, I.T., 1996. Red tuffs in the Palaeocene lava successions of the Inner Hebrides. Scott. J. Geol., 32, 83–9.CrossRefGoogle Scholar
Esson, J., Dunham, A.C. and Thompson, R.N. (1975) Low-alkali, high-calcium olivine tholeiite lavas from the Isle of Skye, Scotland. J. Petrol., 16, 488–97.CrossRefGoogle Scholar
Fisk, M.R. and Bence, A.E. (1980) Experimental crystallisation of Cr-spinel in FAMOUS basalt 527-1-1. Earth Planet. Sci. Lett., 48, 111–23.CrossRefGoogle Scholar
Gibb, F.G.F. (1973) The zoned clinopyroxenes of the Shiant Isles Sill, Scotland. J. Petrol., 14, 203–30.CrossRefGoogle Scholar
Gibson, S.A. (1988) The geochemistry, mineralogy and petrology of the Trotternish sill complex, N Skye, Scotland. Unpublished Ph.D. thesis University of Kingston.Google Scholar
Haggerty, S.E. (1976) Opaque mineral oxides in terrestrial igneous rocks. In: Oxide Minerals. (Rumble, D., ed.). Mineralogical Society of America, Reviews in Mineralogy, Vol. 3.Google Scholar
Harker, A. (1904) The Tertiary Igneous Rocks of Skye. Memoirs of the Geological Survey G.B., Scotland.CrossRefGoogle Scholar
Henderson, P. (1982 ) Inorganic Geochemistry. Pergamon. 353 pp.Google Scholar
Herzberg, C.T. and Chapman, N.A. (1976 ) Clinopyroxene geothermometry of spinel lherzolite. Amer. Mineral., 61, 626–37.Google Scholar
Jurewicz, A.J.G. and Watson, E.B. (1988) Cations in olivine, Part 1: Calcium partitioning and Ca-Mg distribution between olivines and coexisting melts, with petrologic applications. Contrib. Mineral. Petrol., 99, 176–85.CrossRefGoogle Scholar
Kerr, A.C. (1993 a) The geochemistry and petrogenesis of the Mull-Morvern Tertiary lava succession, Argyll, Scotland. Unpublished Ph.D. Thesis. University of Durham.Google Scholar
Kerr, A.C. (1993 b) Elemental evidence for an enriched small-fraction melt input into Tertiary Mull basalts, Western Scotland. J. Geol. Soc. London, 150, 763–9.CrossRefGoogle Scholar
Kerr, A.C. (1995 a) The geochemistry of the Mull-Morvern Tertiary lava succession, NW Scotland; an assessment of mantle sources during plume related volcanism Chem. Geol., 122, 43–58.CrossRefGoogle Scholar
Kerr, A.C. (1995 b) The geochemical stratigraphy, field relations and temporal variation of the Mull-Morvern Tertiary lava succession, NW Scotland. Trans. Roy. Soc. Edinburgh; Earth Sciences.In Press.CrossRefGoogle Scholar
Kerr, A.C., Kempton, P.D. and Thompson, R.N. (1995) Crustal assimilation during turbulent magma ascent (ATA); New isotopic evidence from the Mull Tertiary lava succession N.W. Scotland. Contrib. Mineral. Petrol., 119, 142–54.CrossRefGoogle Scholar
Larsen, L.M., Watt, W.S. and Watt, M. (1989) Geology and petrology of the lower Tertiary plateau basalts of the Scoresby Sund region, East Greenland. Greenland Geol. Surv. Bull., 157, 162 pp.Google Scholar
Marshall, L.A., 1984. Origin of some mixed-magma and net-veined ring intrusions. J. Geol. Soc., London, 141, 171–82.CrossRefGoogle Scholar
Morimoto, N. (1988) The nomenclature of pyroxenes. Mineral. Mag., 52, 535–50.CrossRefGoogle Scholar
Morrison, M.A., Thompson, R.N., Gibson, I.L. and Marriner, G.F. (1980) Lateral chemical heterogeneity in the Palaeocene upper mantle beneath the Scottish Hebrides. Phil. Trans. Royal Soc.; London, A297, 229–44.Google Scholar
Nielsen, R.L. (1988) A model for the simulation of combined major and trace element liquid lines of descent. Geochim. Cosmochim. Acta, 52, 27–38.CrossRefGoogle Scholar
Preston, R.J. and Bell, B.R. (1997) Cognate xenoliths from a tholeiitic subvolcanic sill complex: Implications for fractional crystallisation and crustal contamination processes. Mineral. Mag., 61, 329–49.CrossRefGoogle Scholar
Ridley, W.I. (1977) The crystallisation trends of Spinels in Tertiary basalts from Rhum and Muck and their petrogenetic significance. Contrib. Mineral. Petrol., 64, 243–55.CrossRefGoogle Scholar
Simkin, T. and Smith, J.V. (1970) Minor element distribution in olivine. J. Geol.. 78, 304–25.CrossRefGoogle Scholar
Skelhorn, R.R., MacDougall, J.D.S. and Longland, P.J.N. (1969) The Tertiary igneous geology of the Isle of Mull. Geol. Assoc. Guides, No. 20.Google Scholar
Sparks, R.S.J. and Huppert, H. (1984) Density changes during fractional crystallisation of basaltic magmas: fluid dynamic implications. Contrib. Mineral. Petrol., 85, 300–9.CrossRefGoogle Scholar
Thompson, R.N. (1974) Primary basalts and magma genesis. Contrib. Mineral. Petrol., 45, 317–41.CrossRefGoogle Scholar
Thompson, R.N. and Morrison, M.A. (1988 ) Asthenospheric and lower-lithospheric mantle contributions to continental extensional magmatism: an example from the British Tertiary Province. Chem. Geol., 68, 1–15.CrossRefGoogle Scholar
Thompson, R.N., Esson, J. and Dunham, A.C. (1972) Major element chemical variation in the Eocene lavas of the Isle of Skye. Scotland. J. Petrol., 13, 219–53.CrossRefGoogle Scholar
Thompson, R.N., Dickin, A.P., Gibson, I.L. and Morrison, M.A. (1982) Elemental fingerprints of isotopic contamination of Hebridean Palaeocene mantle derived magmas by Archean sial. Contrib. Mineral. Petrol., 79, 159–68.CrossRefGoogle Scholar
Walker, G.P.L. (1970) The distribution of amygdale minerals in Mull and Morvern (Western Scotland). In Studies in Earth Sciences, West Commemoration Volume. (Murty, T.V.V.G.R.K. and Rao, S.S., eds.). 181–94.Google Scholar
Wallace, J.M., Ellam, R.M., Meighan, I.G., Lyle, P. and Rogers, N.W. (1994) Sr isotope data for the Tertiary lavas of N. Ireland: Evidence for open system processes. J. Geol. Soc., London, 151, 869–77.CrossRefGoogle Scholar
Williamson, I.T. (1979) The petrology and structure of the Tertiary volcanic rocks of West-Central Skye, NW Scotland. Unpublished Ph.D. thesis, University of Durham, UK.Google Scholar