Hostname: page-component-586b7cd67f-dsjbd Total loading time: 0 Render date: 2024-11-23T11:35:25.673Z Has data issue: false hasContentIssue false
  • English
  • Français

The mineral chemistry and petrology of Tertiary pitchstones from Scotland

Published online by Cambridge University Press:  03 November 2011

R. J. Preston ,
M. J. Hole ,
J. Still  and
H. Patton
H. Patton
Affiliation:
Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen, AB24 3UE, [email protected] Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen, AB24 3UE, U.K.
Get access Rights & Permissions [Opens in a new window]

Abstract

Sub-silicic to silicic pitchstones are widespread throughout the British Tertiary Igneous Province (BTIP), with examples being found at all the major igneous centres. Both highly porphyritic and almost completely aphyric varieties occur, and take the form of sills, dykes and lava flows. Here we present previously unreported mineral chemistry data on phenocryst and microcrystallite populations from a number of pitchstones from throughout the BTIP. Phenocryst assemblages are completely anhydrous, comprising mixtures of plagioclase, sanidine, fayalite, orthopyroxene, pigeonite, ferroaugite, ferrohedenbergite and quartz. Microcrystallite assemblages are also diverse, consisting of sanidine, ferrohedenbergite, fayalite and, occasionally, almost pure end-member ferrosilite, as well as hydrous phases such as ferrohornblende and biotite. Textural and mineral chemistry observations support interpretations derived from whole-rock and residual glass major element analyses, together with whole-rock trace element and the available Sr-Nd-Pb isotope data, that the Tertiary pitchstones of Scotland are either the products of intimate mixing between a range of basaltic magmas with hydrous crustal melts, or were formed by the crustal contamination of basaltic magmas.

Keywords

basaltBTIPcrustal meltscrystallitesdisequilibrium phenocrystsglassmagma mixing
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 89 , Issue 2 , 1998 , pp. 95 - 111
Copyright
Copyright © Royal Society of Edinburgh 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

Allport, A. 1872. On the microscopic structure of the pitchstones of Arran. Geological Magazine 9, 110.CrossRefGoogle Scholar
Anderson, E. M.Radley, E. G. 1916. The pitchstones of Mull and their genesis. Quarterly Journal of the Geological Society of London 71, 20516.CrossRefGoogle Scholar
Bailey, E. B., Clough, C. T., Wright, W. B., Richey, J. E.Wilson, G. V. 1924. Tertiary and Post-Tertiary geology of Mull, Loch Aline, and Oban. Memoirs of the Geological Survey of Scotland. Edinburgh: H.M.S.O.Google Scholar
Beckinsale, R. D., Pankhurst, R. J., Skelhorn, R. R.Walsh, J. N. 1978. Geochemistry and petrogenesis of the Early Tertiary lava pile of the Isle of Mull, Scotland. Contributions to Mineralogy and Petrology 66, 41527.CrossRefGoogle Scholar
Bell, B. R.Harris, J. W. 1986. An Excursion Guide to the Geology of the Isle of Skye. Glasgow: The Geological Society of Glasgow.Google Scholar
Bell, B. R.Jolley, D. W. 1997. Application of palynological data to the chronology of the Paleogene lava fields of the British Province: implications for magmatic stratigraphy. Journal of the Geological Society of London 154, 70108.CrossRefGoogle Scholar
Bell, B. R., Claydon, R. V.Rogers, G. 1994. The petrology and geochemistry of cone-sheets from the Cuillin Igneous Complex, Isle of Skye: Evidence for combined assimilation and fractional crystallisation during lithospheric extension. Journal of Petrology 35, 105594.CrossRefGoogle Scholar
Binns, R. A. 1969. High-pressure megacrysts in basaltic lavas near Armidale, New South Wales. American Journal of Science 267-A, 3349.Google Scholar
Binns, R. A., Duggan, M. B.Wilkinson, J. F. G. 1970. High pressure megacrysts in alkaline lavas from north-eastern New South Wales. American Journal of Science 269, 13268.CrossRefGoogle Scholar
Brown, G. M. 1957. Pyroxenes from the early and middle stages of fractionation of the Skaergaard intrusion, East Greenland. Mineralogical Magazine 31, 51143.CrossRefGoogle Scholar
Brown, G. M.Vincent, E. A. 1963. Pyroxenes from the late stages of fractionation of the Skaergaard intrusion, East Greenland. Journal of Petrology 4, 17597.CrossRefGoogle Scholar
Buddington, A. F.Lindsley, D. H. 1964. Iron-titanium oxide minerals and synthetic equivalents. Journal of Petrology, 5, 31057.CrossRefGoogle Scholar
Buist, D. S. 1961. The composite sill of Rudh’ a’ Chromain, Carsaig, Mull. Geological Magazine 98, 6776.CrossRefGoogle Scholar
Carmichael, I. S. E. 1960a. The feldspar phenocrysts of some Tertiary acid glasses. Mineralogical Magazine 32, 587608.CrossRefGoogle Scholar
Cartnichael, I. S. E. 1960b. The pyroxenes and olivines from some Tertiary acid glasses. Journal of Petrology 1, 30936.Google Scholar
Carmichael, I. S. E. 1963a. The occurence of magnesian pyroxenes and magnetite in porphyritic acid glasses. Mineralogical Magazine 33, 394403.CrossRefGoogle Scholar
Carmichael, I. S. E. 1963b. The crystallisation of feldspar in volcanic acid liquids. Quarterly Journal of the Geological Society of London 119, 95131.CrossRefGoogle Scholar
Carmichael, I. S. E., Nicholls, J.Smith, A. L. 1970. Silica activity in igneous rocks. American Mineralogy 55, 24663.Google Scholar
Cox, K. G., Bell, J. D.Pankhurst, R. J. 1979. The Interpretation of Igneous Rocks. London: Unwin Hyman.CrossRefGoogle Scholar
Davidson, C. F. 1935. The Tertiary geology of Raasay, Inner Hebrides. Transactions of the Royal Society of Edinburgh 58, 375407.CrossRefGoogle Scholar
Deer, W. A., Howie, R. A.Zussman, J. 1997. Rock-Forming Minerals. Single Chain Silicates, 2nd edn. London: The Geological Society.Google Scholar
Dickin, A. P.Jones, N. W. 1983. Isotopic evidence for the age and origin of pitchstones and felsites, Isle of Eigg, NW Scotland. Journal of the Geological Society of London 140, 691700.CrossRefGoogle Scholar
Dickin, A. P., Moorbath, S.Welke, H. J. 1981. Isotope, trace element and major element geochemistry of Tertiary igneous rocks, Isle of Arran, Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences 72, 15970.CrossRefGoogle Scholar
Dickin, A. P., Jones, N. W., Thirlwall, M. F.Thompson, R. N. 1987. A Ce/Nd isotope study of crustal contamination processes affecting Palaeocene magmas in Skye, Northwest Scotland. Contributions to Mineralogy and Petrology 96, 45564.CrossRefGoogle Scholar
Donaldson, C. H. 1976. An experimental investigation of olivine morphology. Contributions to Mineralogy and Petrology 57, 187213.CrossRefGoogle Scholar
Donaldson, C. H., Usselman, T. M., Williams, R. J.Lofgren, G. E. 1975. Experimental modelling of the cooling history of Apollo 12 olivine basalts. Proceedings of the 6th Lunar Science Conference, 84370.Google Scholar
Emeleus, C. H., Dunham, A. C.Thompson, R. N. 1971. Iron-rich pigeonites from acid rocks in the Tertiary Igneous Province of Scotland. American Mineralogy 56, 94051.Google Scholar
Finger, L. W. 1972. The uncertainty in the calculated ferric iron content of a microprobe analysis. Carnegie Institute of Washington Yearbook 71, 600603.Google Scholar
Forester, R. W.Taylor, H. P. Jr 1977. 18O/16O, D/H and 13C/12C studies of the Tertiary igneous complex of Skye, Scotland. American Journal of Science 277, 13677.CrossRefGoogle Scholar
Frost, B. R., Lindsley, D. H.Andersen, D. J. 1988. Fe-Ti oxides-silicate equilibria: Assemblages with fayalitic olivine. American Mineralogy 73, 72740.Google Scholar
Gibb, F. G. F. 1973. The zoned clinopyroxenes of the Shiant Isles sill, Scotland. Journal of Petrology 14, 20330.CrossRefGoogle Scholar
Harker, A. 1908. The Geology of the small isles of Inverness-shire. Memoirs of the Geological Survey of Scotland. Edinburgh: H.M.S.O.Google Scholar
Hibbard, M. J. 1995. Petrography to Petrogenesis. London: Prentice-Hall.Google Scholar
Hole, M. J.Morrison, M. A. 1992. The differentiated dolerite boss, Cnoc Rhaonastil, Islay: a natural experiment in the low pressure differentiation of an alkali olivine-basalt magma. Scottish Journal of Geology 28, 5569.CrossRefGoogle Scholar
Ishii, T. 1975. The relations between temperature and composition of pigeonite in some lavas and their application to geothermometry. Mineralogical Journal 8, 4857.CrossRefGoogle Scholar
Judd, J. W. 1893. On composite dykes in Arran. Quarterly Journal of the Geological Society of London 49, 53664.CrossRefGoogle Scholar
Kerr, A. C. 1995. The geochemistry of the Mull-Morvern Tertiary lava succession, NW Scotland: An assessment of mantle sources during plume-related volcanism. Chemical Geology 122, 4358.CrossRefGoogle Scholar
Kretz, R. 1982. Transfer and exchange equilibria in a portion of the pyroxene quadrilateral as deduced from natural and experimental data. Geochimica Cosmochimica Acta 46, 41121.CrossRefGoogle Scholar
Lindsley, D. H. 1983. Pyroxene thermometry. American Mineralogy 68, 47793.Google Scholar
Lindsley, D. H.Andersen, D. J. 1983. A two-pyroxene thermometer. In Proceedings, Thirteenth Lunar and Planetary Science Conference Part 2. Journal of Geophysical Research 88, Supplement, A887A906.Google Scholar
Lofgren, G. 1974. An experimental study of plagioclase crystal morphology: isothermal crystallization. American Journal of Science 274, 24373.CrossRefGoogle Scholar
Lofgren, G. 1980. Experimental studies on the dynamics of crystallisation of silicate melts. In Hargraves, R. B. (ed.) Physics of Magmatic Processes. Princeton NJ: Princeton University Press.Google Scholar
MacDonald, J. G.Herriot, A. 1983. Macgregor's excursion guide to the geology of Arran. Glasgow: Geological Society of Glasgow.Google Scholar
Middlemost, E. A. K. 1975. The basalt clan. Earth Science Review 11, 33764.CrossRefGoogle Scholar
Nekvasil, H. 1992a. Feldspar crystallisation in felsic magmas: a review. Transactions of the Royal Society of Edinburgh: Earth Sciences 83, 399407.CrossRefGoogle Scholar
Nekvasil, H. 1992b. Ternary feldspar crystallisation in high-temperature felsic magmas. American Mineralogy 77, 592604.Google Scholar
Pankhurst, R. J., Walsh, J. N., Beckinsale, R. D.Skelhorn, R. R. 1978. Isotopic and other geochemical evidence for the origin of the Loch Uisg granophyre, Isle of Mull, Scotland. Earth and Planetary Science Letters 38, 35563.CrossRefGoogle Scholar
Preston, R. J.Bell, B. R. 1997. Cognate gabbroic xenoliths from a tholeiitic subvolcanic sill complex: Implications for fractional crystallisation and crustal contamination processes. Mineralogical Magazine 61, 32949.CrossRefGoogle Scholar
Preston, R. J., Bell, B. R.Rogers, G. 1998. The Loch Scridain Xenolithic Sill Complex, Isle of Mull, Scotland: Fractional crystallisation, assimilation, magma-mixing and crustal anatexis in subvolcanic conduits. Journal of Petrology 39, 51950.CrossRefGoogle Scholar
Rice, C. M., Ashcroft, W. A., Batten, D. J., Boyce, A. J., Caulfield, J. B. D., Fallick, A. J., Hole, M. J., Jones, E., Pearson, M. J., Rogers, G., Saxton, J. M., Stuart, F. M., Trewin, N. H.Turner, G. 1995. The geology of an early hot spring system near Rhynie, Scotland. Journal of the Geological Society of London 152, 22550.CrossRefGoogle Scholar
Richey, J. E.Thomas, H. H. 1930. The Geology of Ardnamurchan, NW Mull and Coll. Memoirs of the Geological Survey of Scotland. Edinburgh: H.M.S.O.Google Scholar
Shore, M.Fowler, A. D. 1996. Oscillatory zoning in minerals: a common phenomenon. Canadian Mineralogy 34, 111126.Google Scholar
Smith, D. 1972. Stability of iron-rich pyroxene in the system CaSiO3-FeSiO3-MgSiO3. American Mineralogy 57, 37083.Google Scholar
Smith, D. 1974. Pyroxene-olivine-quartz assemblages in rocks associated with the Nain Anorthosite Massif, Labrador. Journal of Petrology 15, 5878.CrossRefGoogle Scholar
Thomas, H. H. 1922. On certain xenolithic Tertiary minor intrusions in the Island of Mull (Argyllshire). Quarterly Journal of the Geological Society of London 78, 22960.CrossRefGoogle Scholar
Thompson, R. N., Gibson, I. L., Marriner, G. F., Mattey, D. P.Morrison, M. A. 1980. Trace-element evidence of multistage mantle fusion and polybaric fractional crystallisation in the Palaeocene lavas of Skye, NW Scotland. Journal of Petrology 21, 26593.CrossRefGoogle Scholar
Thompson, R. N., Morrison, M. A., Dickin, A. P., Hendry, G. L. 1983. Continental flood basalts… Arachnids rule OK? In Hawkesworth, C. J., Norry, M. J. (eds) Continental Basalts and Mantle Xenoliths, 15885. Cheshire: Shiva Publishing.Google Scholar
Tilley, C. E. 1957. A note on the pitchstones of Arran. Geological Magazine 94, 32933.CrossRefGoogle Scholar
Tilley, C. E.Muir, I. D. 1962. The Hebridean plateau magma type. Transactions of the Royal Society of Edinburgh 19, 20815.Google Scholar
Tuttle, O. F.Bowen, N. L. 1958. Origin of granite in the light of experimental studies in the system NaAlSi3O8-KAlSi3O8-SiO2-H2O. Geological Society of America Memoir 74.CrossRefGoogle Scholar
Tyrrell, G. W. 1928. The Geology of Arran. Memoirs of the Geological Survey of Scotland. Edinburgh: H.M.S.O.Google Scholar
Walsh, J. N., Beckinsale, R. D., Skelhorn, R. R.Thorpe, R. S. 1979. Geochemistry and petrogenesis of Tertiary granitic rocks from the Isle of Mull, Northwest Scotland. Contributions to Mineralogy and Petrology 71, 99116.CrossRefGoogle Scholar
Wilson, M. 1989. Igneous Petrogenesis. London: Unwin Hyman.CrossRefGoogle Scholar
Yoder, H. S. Jr, Stewart, D. B., Smith, J. V. 1957. Ternary feldspars. Carnegie Institute of Washington Yearbook 56, 20614.Google Scholar