Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-19T00:34:15.299Z Has data issue: false hasContentIssue false
  • English
  • Français

Silicate mineralogy of the Behelvie cumulates, N E Scotland

Published online by Cambridge University Press:  05 July 2018

W. J. Wadsworth
W. J. Wadsworth*
Affiliation:
Department of Geology, The University, Manchester M13 9PL
Get access Rights & Permissions [Opens in a new window]

Abstract

Ultramafic, troctolitic and gabbroic rocks at the northern end of the Belhelvie layered intrusion display progressive cryptic variation over a stratigraphic thickness of approximately 800 m in steeply-dipping cumulates, which young from W to E. This variation is shown by olivine (Fo87−77), orthopyroxene (En87−79), clinopyroxene (Ca45Mg48Fe7 to Ca44.5Mg45.5Fe10) and plagioclase (An81−75). The Belhelvie succession is believed to be equivalent to the poorly-exposed and structurally complex Insch Lower Zone. A laterally impersistent hypersthene-gabbro unit within the main sequence is re-interpreted as a downfaulted block of slightly more evolved cumulates. A repeat sequence of peridotites, troctolites and gabbros on the eastern side of the intrusion, and separated from the underlying main succession by a thin septum of country rock, is believed to represent a fresh influx of magma.

Keywords

silicatescryptic variationcumulatesBelhelvieScotland
Type
Research Article
Information
Mineralogical Magazine , Volume 55 , Issue 378 , March 1991 , pp. 113 - 119
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1991

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

Ashcroft, W. A. and Boyd, R. (1976) The Belhelvie mafic igneous intrusion, Aberdeenshire–a re-investigation. Scott. J. Geol., 12, 1–14.CrossRefGoogle Scholar
Ashcroft, W. A. and Munro, M. (1978) The structure of the eastern part of the Insch mafic intrusion, Aberdeenshire. Ibid., 14, 55–79.Google Scholar
Boyd, R. (1972) The geology of the Belhelvie mafic intrusion and its environs, Aberdeenshire. Unpubl. Ph.D. thesis, Univ. of Aberdeen.Google Scholar
Boyd, R. and Munro, M. (1978) Deformation of the Belhelvie mass, Aberdeenshire. Scott. J. Geol., 14, 29–44.CrossRefGoogle Scholar
Eales, H. V., Field, M., de Klerk, W. J., and Scoon, R. N. (1988) Regional trends of chemical variation and thermal erosion in the Upper Critical Zone, Western Bushveld Complex. Mineral. Mag., 52, 63–79.CrossRefGoogle Scholar
McGregor, D. M. and Wilson, R. C. L. (1967) Gravity and magnetic surveys of the younger gahbros of Aberdeenshire. Q. J. Geol. Soc. London, 123, 99–123.CrossRefGoogle Scholar
Munro, M. (1984) Cumulate relation in the ‘Younger Basic’ masses of the Huntly-Portsoy area, Grampian Region. Scott. J. Geol., 20, 343–59.CrossRefGoogle Scholar
Munro, M. (1986a) Geology of the country around Aberdeen. Mem. Br. Geol. Surv., Sheet 77 (Scotland), 124 pp.Google Scholar
Munro, M. (1986b) Mylonite zones in the Insch ‘Younger Basic’ mass. Scott. J. Geol., 22, 132–6.CrossRefGoogle Scholar
Read, H. H. (1923) The petrology of the Arnage district in Aberdeenshire. Q. J. Geol. Soc. London, 79, 132–6.CrossRefGoogle Scholar
Read, H. H. and Farquahar, O. C. (1956) The Buchan anticline of the Banff nappe of Dalradian rocks in north-east Scotland. Ibid., 112, 131–54.Google Scholar
Stewart, F. H. (1946) The gabbroic complex of Belhelvie in Aberdeenshire. Ibid., 102, 464–98.Google Scholar
Stewart, F. H. and Johnson, M. R. W. (1960) The structural problems of the younger gabbros of north-east Scotland. Trans. Edinb. Geol. Soc., 18, 104–12.CrossRefGoogle Scholar
Wadsworth, W. J. (1970) The Aberdeenshire layered intrusion of north-east Scotland. Geol. Soc. S. Africa. Special Publication, 1, 566–75.Google Scholar
Wadsworth, W. J. (1982) The basic plutons. In Igneous Rocks of the British Isles (D. S. Sutherland, ed.). J. Wiley & Sons, 135–48.Google Scholar
Wadsworth, W. J. (1986) Silicate mineralogy in the later fractionation stages of the lnsch intrusion, N.E. Scotland. Mineral. Mag., 50, 583–95.CrossRefGoogle Scholar
Wadsworth, W. J. (1988) Silicate mineralogy of the Middle Zone cumulates and associated gabbroic rocks from the Insch intrusion N.E. Scotland. Ibid., 52, 309–22.Google Scholar
Stewart, F. H., and Rothstein, A. T. V. (1966) Cryptic layering in the Belhelvie intrusion, Aberdeenshire. Scott. J. Geol. 2, 54–66.Google Scholar
Weedon, D. S. (1970) The ultrabasic/basic igneous rocks of the Huntly region. Ibid., 6, 26–40.Google Scholar