Hostname: page-component-848d4c4894-ndmmz Total loading time: 0 Render date: 2024-06-08T08:27:58.182Z Has data issue: false hasContentIssue false
  • English
  • Français

Kinetics of pyrope megacryst reactions in ascending basaltic magma – relevance to high-pressure magmatic crystallization at Elie Ness, East Fife

Published online by Cambridge University Press:  01 May 2009

Colin H. Donaldson
Colin H. Donaldson
Affiliation:
Department of Geology, University of St Andrews, St Andrews, Fife KYI6 9ST, Scotland
Get access Rights & Permissions [Opens in a new window]

Abstract

The rates of resorption of pyrope in basaltic melt and of pyrope decomposition to pyroxene + melt at pressures below the stability of garnet are used to examine the proposition (Chapman, 1976) that pyrope megacrysts in the Elie Ness neck began ascent from the mantle at 1300–1450°C. Both reactions are extremely rapid at these temperatures and yet the petrographic evidence is that neither occurred. Either the transporting magma cooled extremely rapidly during ascent (> 30000 °/h) or, more likely, was considerably cooler than previously proposed. Water was a significant constituent of the magma, and a crystallization temperature for the garnet of as little as 1000 °C is possible, based on existing phase–equilibria data.

Type
Articles
Information
Geological Magazine , Volume 121 , Issue 6 , November 1984 , pp. 615 - 620
Copyright
Copyright © Cambridge University Press 1984

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

Anderson, O. L. 1979. The role of fracture dynamics in kimberlite pipe formation. In Kimberlite Diatremes and Diamonds. Their Geology, Petrology and Geochemistry (eds. Boyd, F. R and Mayer, H. O. A.), pp. 344–53. American Geophysical Union.CrossRefGoogle Scholar
Balsillie, D. 1927. Contemporaneous volcanism in East Fife. Geological Magazine 64, 481–94.CrossRefGoogle Scholar
Boyd, F. R. & Nixon, P. H. 1980. Discrete nodules from the kimberlites of East Griqualand, southern Africa. Carnegie Institute of Washington Yearbook 79, 196–302.Google Scholar
Chapman, N. A. 1976. Inclusions and megacrysts from undersaturated tuffs and basanites, East Fife, Scotland. Journal of Petrology 16, 472–98.CrossRefGoogle Scholar
Chapman, N. A. & Powell, R. 1976. Origin of anorthoclase megacrysts in alkali basalts. Contributions to Mineralogy and Petrology 58, 29–35.CrossRefGoogle Scholar
Colvine, R. J. L. 1968. Pyrope from Elie, Fife. Scottish Journal of Geology 4, 283–6.CrossRefGoogle Scholar
Cumming, G. A. 1935. The structural and volcanic geology of the Elie–St. Monance district, Fife. Transactions of the Edinburgh Geological Society 13, 340–65.CrossRefGoogle Scholar
Dawson, J. B. D. 1980. Kimberlites and Their Xenoliths. Berlin: Springer-Verlag.CrossRefGoogle Scholar
Dawson, J. B. & Stephens, W. E. 1976. Statistical classification of garnets from kimberlites and associated xenoliths – addendum. Journal of Geology 84, 495–6.CrossRefGoogle Scholar
Dickey, J. S. 1968. Eclogitic and other inclusions in the Mineral Breccia Member of the Deborah Volcanic Formation at Kakanui, New Zealand. American Mineralogist 53, 1304–19.Google Scholar
Donaldson, C. H. 1984. Crystal dissolution rates in a basaltic melt. In Progress in Experimental Petrology N.E.R.C. (in press).Google Scholar
Francis, E. H. 1977. Volcanic Necks. In The Geology of East Fife (Forsyth, I. H & Chisholm, J. I), pp 171–220. Memoir, Geological Survey of Great Britain.Google Scholar
Francis, E. H. & Hopgood, A. M. 1970. Volcanism and the Ardross Fault. Scottish Journal of Geology 6, 162–85.CrossRefGoogle Scholar
Geikie, A. 1902. The Geology of Eastern Fife. Memoir, Geological Survey of Scotland, Edinburgh.Google Scholar
Heddle, M. F. 1901. The Mineralogy of Scotland, vol. 2 pp. 47–8. St Andrews University Press.Google Scholar
Hunter, R. H. & Taylor, L. A. 1982. Instability of garnet from the mantle: glass as evidence of metasomatic melting. Geology 10, 617–20.2.0.CO;2>CrossRefGoogle Scholar
Macintyre, R. M., Cliff, R. A. & Chapman, N. A. 1981. Geochronological evidence for phased volcanic activity in Fife and Caithness necks, Scotland. Transactions of the Royal Society of Edinburgh 72, 1–7.CrossRefGoogle Scholar
McCallister, R. H., Mayer, H. O. A. & Aragon, R. 1979. Partial thermal history of two exsolved clinopyroxenes from the Thaba Putsoa kimberlite pipe, Lesotho. In Proceedings of the 2nd International Kimberlite Conference, vol. 2, pp. 244–7.Google Scholar
Mason, B. 1966. Pyrope, augite and hornblende from Kakanui, New Zealand. New Zealand Journal of Geology and Geophysics 9, 474–80.CrossRefGoogle Scholar
Merrill, R. B. & Wyllie, P. J. 1975. Kaersutite and kaer-sutite eclogite from Kakanui New Zealand – water-excess and water-deficient melting to 30 kilobars. Geological Society of America Bulletin 86, 555–70.2.0.CO;2>CrossRefGoogle Scholar
Mitchell, R. H., Carswell, D. A. & Clarke, D. B. 1980. Geological implications and validity of calculated equilibration conditions for ultramafic xenoliths from the Pipe 200 kimberlite, Northern Lesotho. Contributions to Mineralogy and Petrology 72, 205–17.CrossRefGoogle Scholar
Scarfe, C. M., Takahashi, E. & Yoder, H. S. 1980. Rates of dissolution of upper mantle minerals in an alkali–olivine basalt melt at high pressures. Carnegie Institute of Washington Yearbook 79, 290–6.Google Scholar
Wyllie, P. J. 1971. The Dynamic Earth. New York. Wiley.Google Scholar