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The Wolf Rock, Cornwall: new chemical, isotopic age and palaeomagnetic data

Published online by Cambridge University Press:  01 May 2009

R. K. Harrison ,
N. J. Snelling ,
R. J. Merriman ,
G. E. Morgan  and
A. J. J. Goode
R. K. Harrison
Affiliation:
Institute of Geological Sciences, Exhibition Road, London SW7 2DE
N. J. Snelling
Affiliation:
Institute of Geological Sciences, Gray's Inn Road, London WC1X 8NG
R. J. Merriman
Affiliation:
Institute of Geological Sciences, Exhibition Road, London SW7 2DE
G. E. Morgan
Affiliation:
Department of Earth sciences, The University, Leeds 2
A. J. J. Goode
Affiliation:
Institute of Geological Sciences, Hoopern House, 101, Pennsylvania Road, Exeter, EX4 6DT
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Summary

By systematic sampling (including the drilling of orientated cores) new data are presented on the chemistry, petrography, mineralogy, K/Ar isotopic age and remanent magnetism of the Wolf Rock, Cornwall. The overall homogeneity of the Rock is confirmed as a fine-grained fluxioned microporphyritic phonolite. Major joints strike NNW–SSE and NNE–SSW and there is a pronounced floor jointing. New whole-rock and probe analyses of the constituent minerals are given. Nosean, previously recorded, is found to be replaced by analcime, cancrinite and other minerals. K–Ar determinations on nepheline and K-feldspar give mean ages of 112±2, and 130±6 Ma respectively. The mean pole position of 70° N, 6° E, suggests that the 130 Ma pole for stable Europe may have been somewhat closer to Europe than previously supposed. The significance of this Lower Cretaceous magmatism in the context of Mesozoic volcanism in Southern England and European alkaline provinces is discussed.

Type
Articles
Information
Geological Magazine , Volume 114 , Issue 4 , July 1977 , pp. 249 - 264
Copyright
Copyright © Cambridge University Press 1977

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References

Allport, S. 1871. On the microscopical structure and composition of a phonolite from the ‘Wolf Rock’. Geol. Mag. 8, 247–50.Google Scholar
Allport, S. 1874. Note on the phonolite from the ‘Wolf Rock’. Geol. Mag. 10, 462–3.Google Scholar
Bailey, D. K. 1964. Crustal warping – a possible tectonic control of alkaline magmatism. J. geophys. Res. 69, 1103–11.Google Scholar
Bailey, D. K. & Shairer, J. F. 1966. The system Na2O–Al2O3–Fe2O3–SiO2 at 1 atmosphere and the petrogenesis of alkaline rocks. J. Petrology 7, 114–70.CrossRefGoogle Scholar
Bott, M. H. P. & Watts, A. B. 1970. Deep structure of the continental margin adjacent to the British Isles. Report 70/14, Inst. of Geol. Sci. pp. 93–114.Google Scholar
Bowen, N. L. 1937. Recent high-temperature research on silicates and its significance in igneous geology. Am. J. Sci. 33, 1–21.Google Scholar
Clark, L. M. 1948. The identification of minerals in boiler deposits. Examples of hydrothermal synthesis in boilers. Mineralog. Mag. 28, 359–66.Google Scholar
Cottençon, A., Parant, B. & Flacelière, G. 1975. Lower Cretaceous gas-fields in Holland. In Petroleum and the Continental Shelf of North-West Europe. Vol. 1, Geology (ed. Woodland, A. W.), 402–12. Applied Science Publishers, Barking, England.Google Scholar
Cowperthwaite, I. A., Fitch, F. J., Miller, J. A., Mitchell, J. G. & Robertson, R. H. S. 1972. Sedimentation, petrogenesis and radioisotope age of the Cretaceous fuller's earth of Southern England. Clay Miner. 9, 309–27.CrossRefGoogle Scholar
Curry, D., Hamilton, D., & Smith, A. J. 1970. Geological evolution of the western English Channel and its relation to the nearby continental margin. Report 70/14, Inst. geol. Sci. pp. 129–56.Google Scholar
Dalrymple, G. V. & Lanphere, M. A. 1969. Potassium-argon Dating. San Francisco: W. H. Freeman.Google Scholar
Daly, R. A. 1933. Igneous Rocks and the Depths of the Earth. New York: McGraw-Hill.Google Scholar
Deer, W. A., Howie, R. A. & Zussman, J. 1963. Rock-Forming Minerals. Vol. 2: Chain Silicates. Vol. 4: Framework Silicates. London: Longmans.Google Scholar
Dodson, M. H. & Rex, D. C. 1971. Potassium—argon ages of slates and phyllites from S. W. England. Q. Jl geol. Soc. Lond. 126, 465–99.Google Scholar
Edgar, A. D. 1964. Studies on cancrinites. II. Stability fields and cell dimensions of calcium and potassium-rich cancrinites. Can. Miner. 8, 53–67.Google Scholar
El-Hinnawi, E. E. 1964. Petrochemical characters of African volcanic rocks. 1. Ethiopia and Red Sea Region (including Yemen and Aden). Neues Jahr. Min. pp. 65–81.Google Scholar
Goles, G. G. 1976. Some constraints on the origin of phonolites from the Gregory Rift, Kenya, and inferences concerning basaltic magmas in the Rift System. Lithos 9, 1–8.CrossRefGoogle Scholar
Halliday, A. N. & Mitchell, J. G. 1976. Structural, K–Ar, and 40Ar–39Ar age studies of adularia K-feldspar from the Lizard Complex, England. Earth Planet. Sci. Lett. 29, 227–337.CrossRefGoogle Scholar
Hyndman, D. W. 1972. Petrology of Igneous and Metamorphic Rocks. New York: McGraw-Hill.Google Scholar
Jeans, C. V., Merriman, R. J. & Mitchell, J. G. 1977. Origin of Bathonian and Lower Cretaceous Fuller's earths in England. Clay Miner. 12, 11–44.CrossRefGoogle Scholar
Lefort, J.-P. 1973. La ‘zonale’ Biscaye-Labrador: mise en évidence de cisaillements dextres antérieurs à l'ouverture de l'Atlantiques Nord. Mar. Geol. 14, M33–8.CrossRefGoogle Scholar
Lippard, S. J. 1973. The petrology of phonolites from the Kenya Rift. Lithos 6, 217–234.CrossRefGoogle Scholar
Lowndes, A. G. 1955. The Wolf Rock Rock phonolite used for tracing deep-water drift in the English Channel. Sci. Progr. 43, 434–45.Google Scholar
Miller, J. A. & Mohr, P. A. 1964. Potassium–argon measurements on the granites and some associated rocks from south-west England. Geol. J. 4, 105–26.CrossRefGoogle Scholar
Mitchell, J. G., MacIntyre, R. M. & Pringle, I. R. 1975. K–Ar and Rb–Sr isotope age studies on the Wolf Rock nosean-phonolite, Cornwall. Geol. Mag. 112, 55–61.CrossRefGoogle Scholar
Sallomy, J. T. & Briden, J. C. 1975. Palaeomagnetic studies of Lower Jurassic Rocks in England and Wales. Earth Planet. Sci. Lett. 24, 369–76.CrossRefGoogle Scholar
Schairer, J. F. 1950. The alkaline-feldspar join in the system Na Al SiO4–KAl SiO4–SiO2. J. Geol. 58, 512–17.CrossRefGoogle Scholar
Seager, A. F. 1967/1968. Mineralization and paragenesis at Dean Quarry, the Lizard, Cornwall. Trans. R. geol. Soc. Corn. 20, 97–113.Google Scholar
Seager, A. F., Fitch, J. F. & Miller, J. A. 1975. Dating post-metamorphic hydrothermal mineralization in the Lizard complex, Cornwall. Geol. Mag. 112, 519–22.Google Scholar
Snelling, N. J. 1968. In: Annual Report for 1967. Inst. geol. Sci. London.Google Scholar
Sørensen, H. (Ed). 1974. The Alkaline Rocks. New York: Wiley.Google Scholar
Teall, J. J. H. 1888. British Petrography. viii + 469 pp. London: Dulau.Google Scholar
Tilley, C. E. 1959. A note on the nosean phonolite of the Wolf Rock, Cornwall. Geol. Mag. 96, 503–4.Google Scholar
Van der Voo, R. & French, R. B. 1974. Apparent polar wandering for the Atlantic-bordering continents: Late Carboniferous to Eocene. Earth-Science Reviews, 10, 99–119.Google Scholar
Williams, C. A. 1975. Sea-floor spreading in the Bay of Biscay and its relationship to the North Atlantic. Earth Planet. Sci. Lett. 24, 440–56.CrossRefGoogle Scholar