Hostname: page-component-586b7cd67f-tf8b9 Total loading time: 0 Render date: 2024-11-25T03:50:02.137Z Has data issue: false hasContentIssue false
  • English
  • Français

The geology and geochemistry of the strathy complex of north-east Sutherland, Scotland

Published online by Cambridge University Press:  05 July 2018

Valerie E. Moorhouse  and
Steven J. Moorhouse
Valerie E. Moorhouse
Affiliation:
Geological Sciences, School of Natural Sciences, The Hatfield Polytechnic, Hatfield, Hertfordshire AL10 9AB
Steven J. Moorhouse
Affiliation:
Geological Sciences, School of Natural Sciences, The Hatfield Polytechnic, Hatfield, Hertfordshire AL10 9AB
Get access Rights & Permissions [Opens in a new window]

Abstract

The Strathy complex is a fault-bounded block of the sub-Moine succession basement characterized by a marked aeromagnetic anomaly. XRF analyses of 94 rocks for 26 elements are used to illustrate the geochemistry of the complex. It comprises siliceous grey gneisses (50 analyses), subordinate amphibolite (13 analyses), hornblende gneiss (13 analyses), and ultramafites (1 analysis), with scapolite-diopside marble and calc-silicate rocks (3 analyses from Strathy, 14 analyses of other calc-silicates). Geochemically the Strathy gneisses are quite distinct from the adjacent Moine lithologies, being unusually low in K, Rb, La, and Ce, and high in SiO2 and Na2O, whilst differences in immobile elements such as Ti and Zr preclude their derivation from a Moine source. The Strathy complex is unlike other high-grade gneiss terrains and apparently acquired its characteristic geochemical features by the removal of an anatectic melt under amphibolite-facies conditions leaving a refractory residue of quartz, plagioclase, Ca-poor amphibole, and garnet ± staurolite in siliceous gneisses. Subsequent influx of water, retrogression to biotite-bearing assemblages, production of sillimanite, and anateclic trondhjemitic melts took place during the maximum metamorphism of the surrounding Moine. The complex is considered to have originated as a dacitic supracrustal sequence with minor sediments and mafic-ultramafic intrusives. REE and Y abundances suggest a Proterozoic age, possibly as part of the Laxfordian cycle.

Type
Research Article
Information
Mineralogical Magazine , Volume 47 , Issue 343 , June 1983 , pp. 123 - 137
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1983

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

Arth, J. G., and Hanson, G. N. (1975) Geochim. Cosmochim. Ada, 39, 325–62.CrossRefGoogle Scholar
Brown, P. E. (1967) Contrib. Mineral. Petrol. 14, 1–26.CrossRefGoogle Scholar
Brown, P. E. (1971) Mineral. Mag. 38, 446–50.CrossRefGoogle Scholar
Collins, R. S. (1941) Univ. Lond. Ph.D. thesis (unpubl.).Google Scholar
Cooper, D. C. and Field, D. (1977) Earth Planet. Sci. Lett. 35, 105–15.CrossRefGoogle Scholar
Frey, F. A. (1969) Geochim. Cosmochim. Ada, 33, 1429–47.CrossRefGoogle Scholar
Harrison, V. E., and Moorhouse, S. J. (1976) J. Geol. Soc. Lond. 132, 461–6.CrossRefGoogle Scholar
Holland, J. G., and Lambert, R. StJ. (1975) Precambrian Res. 2, 161–88.CrossRefGoogle Scholar
Home, J., and Greenly, E. (1896) Q. J. geol. Soc. Lond. 52, 633–50.Google Scholar
Knabe, W. (1966) Univ. Gottingen Ph.D. thesis (unpubl.), in Winkler, H. G. F. (1967) q.v. Google Scholar
Moorhouse, S. J. (1976) Scott. J. Geol. 12, 159–65.CrossRefGoogle Scholar
Moorhouse, S. J. and Harrison, V. E. (1976) Nature, 259, 249–50.CrossRefGoogle Scholar
Moorhouse, S. J. and Moorhouse, V. E. (1977) Scott. J. Geol. 13, 289– 300.CrossRefGoogle Scholar
Moorhouse, S. J. (1979a) Mineral. Mag. 43, 211–25.CrossRefGoogle Scholar
Moorhouse, S. J. (1979b) Scott. J. Geol. 15, 69–70.CrossRefGoogle Scholar
Moorhouse, V. E. (1979) Univ. Hull Ph.D. thesis (unpubl.).Google Scholar
Read, H. H. (1931) The Geology of Central Sutherland. Mem. Geol. Surv. G.B.Google Scholar
Schreyer, W., and Seifert, F. (1969) Am. J. Sci. 267, 371–88.CrossRefGoogle Scholar
Sheraton, J. W., Skinner, A. C. and Tarney, J. (1973) In The early Precambrian of Scotland and related rocks of Greenland (Park, R. G., and Tarney, J., eds.), Univ. of Keele, 13–30.Google Scholar
Tarney, J. (1976) In The Early History of the Earth (Windley, B. F., ed.), Wiley, London, 405–17.Google Scholar
Tarney, J. and Windley, B. F. (1977) J. Geol. Soc. Lond. 134, 153–72.CrossRefGoogle Scholar
Taylor, S. R. (1965) Phys. Chem. Earth, 6, 133–213.CrossRefGoogle Scholar
Turner, F. J. (1968) Metamorphic Petrology, McGraw- Hill, New York.Google Scholar
Winchester, J. A. and Lambert, R. StJ. (1970) Proc. Geol. Assoc. Lond. 81, 275–301.CrossRefGoogle Scholar
Winchester, J. A. and Floyd, P. A. (1977) Chem. Geol. 20, 325–43.CrossRefGoogle Scholar
Winkler, H. G. F. (1967) Petrogenesis of Metamorphic Rocks, Springer-Verlag, Berlin.CrossRefGoogle Scholar
Wright, A. E., Tarney, J., Palmer, K. F., Moorlock, B. S. P., and Skinner, A. C. (1973) In The early Precambrian of Scotland and related rocks of Greenland (Park, R. G., and Tarney, J., eds.), Univ. of Keele, 157–77.Google Scholar