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A gravity survey of Islay, Scotland

Published online by Cambridge University Press:  01 May 2009

E. M. Durrance
E. M. Durrance
Affiliation:
Department of Geology, University of Exeter, Exter, Devon
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Summary

The results of a gravity survey of Islay indicate that, with respect to a local Bouguer anomaly datum of 260 g.u., a positive anomaly of 100 g.u. occurs over the Lewisian gneiss of the Rhinns of Islay, and, immediately to the E, a negative anomaly of —120 g.u. occurs S of Bowmore. Both anomalies trend N—E to S—W. The negative anomaly is interpreted as due to the presence of a structural basin occupied by a maximum 4600 m of Bowmore Sandstones and Dalradian meta-sediments. The boundary between the Lewisian gneiss and this basin is the Loch Indaal fault. At the head of Loch Indaal this fault bifurcates, one branch continuing north-eastwards as the Bonahaven fault, the other trending northwards as the Loch Gruinart fault, All the faults are considered to possess transcurrent components. The stratigraphic position of the Bowmore Sandstones is similar to that of the supposed Torridonian sediments of western Islay.

Type
Articles
Information
Geological Magazine , Volume 113 , Issue 3 , May 1976 , pp. 251 - 261
Copyright
Copyright © Cambridge University Press 1976

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References

Bailey, E. B. 1917. The Islay anticline (Inner Hebrides). Q. Jl. geol. Soc. Lond. 72, 132–59.CrossRefGoogle Scholar
Bailey, E. B. & Maufe, H. B. 1960. The geology of Ben Nevis and Glen Coe. Mem. geol. Surv U.K. (Scotland).Google Scholar
Bailey, R. J., Buckley, J. S. & Kielmas, M. M. 1975. Geomagnetic reconaissance on the continental margin of the British Isles between 54° and 57° N. Jl. geol. Soc. Lond. 131, 275–82CrossRefGoogle Scholar
Bott, M. H. P. & Watts, A. B. 1970. The Great Glen fault in the Shetland area. Nature, Lond. 227, 269.CrossRefGoogle Scholar
Bullerwell, W. 1972. Aeromagnetic map of Great Britain — Sheet 1. Institute of Geological Sciences.Google Scholar
Dobson, M. R. & Evans, D. 1974. The geological structure of the Malin Sea. Jl. geol. Soc. Lond. 130, 475–8.CrossRefGoogle Scholar
Dobson, M. R., Evans, D. & Wittington, R. 1975. The offshore extension of the Loch Gruinart fault, Islay. Scott. J. Geol. 11, 23–35.CrossRefGoogle Scholar
Flinn, D. 1969. A geological interpretation of the aeromagnetic maps of the continental shelf around Orkney and Shetland. Geol. J. 6, 279–92.CrossRefGoogle Scholar
Garson, M. S. & Plant, J. 1972. Possible dextral movements on the Great Glen and Minch faults in Scotland. Nature Phys. Sci. 240, 31–5.CrossRefGoogle Scholar
Holgate, N. 1969. Palaeozoic and Tertiary transcurrent movements on the Great Glen Fault. Scott. J. Geol. 5, 97–139.CrossRefGoogle Scholar
Johnstone, G. S. 1966. British Regional Geology — The Grampian Highlands. Institute of Geological SciencesGoogle Scholar
Kennedy, W. Q. 1946. The Great Glen fault. Q. Jl. geol. Soc. Lond. 102, 41–72.CrossRefGoogle Scholar
McQuillin, R. & Tuson, J. 1965. Interpretations from gravity measurements of the sizes of some British Tertiary granites. Proc. geol. Soc. Lond. 1621, 59–60.Google Scholar
Pitcher, W. S. 1969. Northeast-trending faults of Scotland and Ireland, and chronology of displacements. In Kay, M. (Ed.): North Atlantic — geology and continental drift, a symposium, Mem. Amer. Ass. Petrol. Geol. 12 724–33.Google Scholar
Powell, D. W. 1970. Magnetised rocks within the Lewisian of Western Scotland and under the Southern Uplands. Scott. J. Geol. 6, 353–69.CrossRefGoogle Scholar
Riddihough, R. P. 1968. Magnetic surveys off the north coast of Ireland, Proc. R. Ir. Acad. B 66, 27–41.Google Scholar
Riddihough, R. P. & Young, D. G. G. 1971. Gravity and magnetic surveys of Inishowen and adjoining sea areas off the north coast of Ireland. Proc. geol. Soc. Lond. 1664, 215–20.Google Scholar
Stewart, A. D. 1962. On the Torridonian sediments of Colonsay and their relationship to the main outcrop in north-west Scotland. Lpool. Manchr. Geol. J. 3, 121–56.CrossRefGoogle Scholar
Stewart, A. D. 1969. Torridonian rocks of Scotland reviewed. In Kay, M. (Ed.): North Atlantic—geology and continental drift, a symposium. Mem. Amer. Ass. Petrol. Geol. 12, 595–608.Google Scholar
Stewart, A. D. & Hackman, B. D. 1973. Precambrian sediments of western Islay. Scott. J. Geol. 9, 185–201.Google Scholar
Walker, F. 1960. The Islay—Jura dyke swarm, Trans. geol. Soc. Glasg. 24, 121–37.Google Scholar
Wilkinson, S. B. 1907. The geology of Islay, including Oronsay and portions of Colonsay and Jura. Mem. geol. Surv U.K. (Scotland).Google Scholar
Wright, W. B. & Bailey, E. B. 1911. The geology of Colonsay and Oronsay, with part of the Ross of Mull. Mem. geol. Surv U.K. (Scotland).Google Scholar