Skip to main content Accessibility help
×
Home

Genesis of porphyry and plutonic mineralisation systems in metaluminous granitoids of the Grampian Terrane, Scotland

  • David Lowry (a1), Adrian J. Boyce (a2), Anthony E. Fallick (a2) and W. Edryd Stephens (a1)

Abstract

Mineralisation associated with Late Caledonian metaluminous granitoids in the Grampian Terrane has been investigated using stable isotope, fluid inclusion and mineralogical techniques.

A porphyry-stock-related style of mineralisation in the Grampian Terrane is characterised by a stockwork of veinlets and disseminations in dacite prophyries, consisting of quartz, dolomite, sulphides and late calcite, and well-developed wallrock alteration dominated by zones of phyllic, sericitic and propylitic alteration. On the basis of δ34S (+0·4±l·0‰), δ13C (−5·7‰ to + l·4‰) and δ18O (+10·8‰ to +19·9‰) it is likely that initial mineralising components were orthomagmatic with an input of external fluids during the later parageneses. Fluids were saline, boiling (up to 560°C), deficient in CO2, and ore deposition took place at depths of less than 3 km.

Plutonic-hosted mineralisation in appinites, diorites, tonalites and monzogranites is commonly represented by sporadic disseminations and occasional veins consisting of quartz, calcite and sulphides. Wallrock alteration is generally propylitic with phyllic vein selvages. Deposition from a cooling magma sourced fluid is indicated by δ34S (+2·6±l·5‰), δ13C (−7·2‰ to −4·5‰) and δ18O (+9·5‰ to + ll·8‰) data. Fluids were CO2-rich and of low salinity; inclusions were trapped below ≈460°C, and formed at estimated depths of 3–5 km.

Differences between these styles of mineralisation may due to multiple factors, the most important being the nature of the fluid: porphyry systems are dominated by greater volumes and much higher temperatures of hydrothermal fluids. Other controlling factors are likely to be the compositional characteristics of the melt source region, the mechanism of magma ascent, the level of emplacement, and the nature of the host metasediments. Variations in δ34S between the two groups are related, for the most part, to redox processes during magma and fluid genesis and not by crustal contamination.

Nolarge porphyry-related mineral deposits have been found in the Grampian Terrane, unlike those in Mesozoic and Tertiary continental margin environments. This is largely due to a combination of detrimental factors which massively reducesthe probability of economic mineralisation. These include the already metamorphosed nature of the host Dalradian, the absence of seawater (which entered many subduction-related magmatic systems), a poorly-developed system of deep faults (most deposits too deep to be influenced by surface-derived fluids), and the absence of supergene enrichment. The main processes which aid the concentration of mineralisation involve encroachment of external fluids (formation, meteoric and seawaters) into the magmatic system, but these fluids were largely absent from the Grampian host block at the time of granitoid intrusion.

The results of this study can be used in characterising the sources of fluids in sedimentary-hosted ore veins known (or considered) to be underlain by metaluminous granitoid batholiths, particularly in estimating the degree of magmatic fluid inputs into the vein systems: an example where this interaction has occurred (the Tyndrum Fault Zone) is discussed.

Copyright

References

Hide All
Chaussidon, M. & Lorand, J. P. 1990. Sulphur isotope composition of orogenic spinel lherzolite massifs from Ariege (North-Eastern Pyrenees, France): An ion microprobe study. GEOCHIM COSMOCHIM ACTA 54, 2835–46.
Clayburn, J. A. P., Harmon, R. S., Pankhurst, R. J. & Brown, J. F. 1983. Sr, O, and Pb isotope evidence for origin and evolution of Etive Igneous Complex, Scotland. NATURE 303, 492–7.
Craig, H. 1957. Isotope standards for carbon and oxygen and correction factors for mass-spectrometric analysis of carbon dioxide. GEOCHIM COSMOCHIM ACTA 12, 133–49.
Curtis, S. F., Pattrick, R. A. D., Jenkin, G. R. T., Fallick, A. E., Boyce, A. J. & Treagus, J. E. 1993. Fluid inclusion and stable isotope study of fault-related mineralisation in the Tyndrum area, Scotland. TRANS INSTN MIN METALL (SECT B) 102, 3947.
Ellis, R. A., Coats, J. S., Fortey, N. J., Johnson, C. E. & Parker, M. E. 1977. Investigation of disseminated coppe mineralization near Kilmelford, Argyllshire, Scotland. BGS MINER RECONNAISSANCE REP 9.
Ellis, R. A., Marsden, G. R. & Fortey, N. J. 1978. Disseminated sulphide mineralization at Garbh Achadh, Argyllshire, Scotland. BGS MINER RECONNAISSANCE REP 23.
Evans, A. M., Haslam, H. W. & Shaw, R. P. 1979. Porphyry style copper-molybdenum mineralization in the Ballachulish igneous complex, Argyllshire, with special reference to fluid inclusions. PROC GEOL ASSOC 96, 4751.
Fallick, A. E., Jocelyn, J., Donnelly, T., Guy, M. & Behan, C. (1985). Origin of agates in volcanic rocks fro Scotland. NATURE 313, 672–4.
Field, C. W. 1973. Sulfur isotope abundances in hydrothermal sulfatesulfide assemblages of the American Cordillera. GEOL SOC AM, ABS WITH PROGS 10, 619.
Field, C. W. & Gustafson, L. B. 1976. Sulfur isotopes in the porphyry copper deposit at El Salvador, Chile. ECON GEOL 71, 1533–48.
Freidman, I. & O'Neil, J. R. 1977. Compilation of stable isotope fractionation factors of geochemical interest. In Fleischer, M. (ed.) Data of Geochemistry (6th Ed.), USGS PROF PAP 440–KK.
Godwin, C. I., Watson, P. H. & Shen, K. 1986. Genesis of the Lass vein system, Beaverdell silver camp, south central British Columbia. CAN J EARTH SCI 23, 1615–26.
Graham, C. M., Greig, K. M., Sheppard, S. M. F. & Turi, B. 1983. Genesis and mobility of the H2O-CO2 fluid phase during regional greenschist and epidote amphibolite facies metamorphism: a petrological and stable isotope study in the Scottish Dalradian. J GEOL SOC LONDON 140, 577–99.
Haas, J. L. 1971. The effect of salinity on the maximum thermal gradient of a hydrothermal systemat hydrostatic pressure. ECON GEOL 66, 940–46.
Hall, A. J., Boyce, A. J. & Fallick, A. E. 1987. Iron sulphides in metasediments: isotopic support fora retrogressive pyrrhotite to pyrite reaction. CHEM GEOL (ISOT GEOSCIE SECT) 65, 305-10.
Hall, A. J., Boyce, A. J. & Fallick, A. J. 1988. A sulphur isotope study of iron sulphides in the Late Precambrian Dalradian Easdale Slate Formation, Argyll, Scotland. MINERAL MAG 52, 483–90.
Hall, A. J., Boyce, A. J. & Fallick, A. J. 1994. A sulphur isotope study of iron sulphides in the late Precambrian Dalradian Ardrishaig Phyllite Formation, Knapdale, Argyll. SCOTT J GEOL 30, 6371.
Harris, M., Kay, E. A., Widnall, M. A., Jones, E. M. & Steele, G. B. 1988. Geology and mineralisation of the Lagalochan intrusive complex, western Argyll, Scotland. TRANS INSTN MINMETALL (SECT B) 97, 1521.
Harmon, R. S. & Halliday, A. N. 1980. Oxygen and strontium isotope relationships in the British Late Caledonian granites. NATURE 283, 21–5.
Haslam, H. W. & Kimbell, G. S. 1981. Disseminated copper-molybdenum mineralisation near Ballachulish, Highland Region. BGS MINER RECONNAISSANCE PROG REP 43.
Haslam, H. W. & Cameron, D. G. 1985. Disseminated molybdenum mineralisation in the Etive plutonic complex in the western Highlands of Scotland. BGS MINER RECONNAISSANCE PROG REP 76.
Hutton, D. H. W. 1987. Strike-slip terranes and a model for the evolution of the British and Irish Caledonides. GEOL MAG 124, 405–25.
Ionov, D. A., Hoefs, J., Wedepohl, K. H. & Wiechert, U. 1992. Contentand isotopic composition of sulphur in ultramafic xenoliths from central Asia. EARTH PLANET SCI LETTS 111, 269–86.
Ishihara, S. & Sasaki, A. 1989. Sulfur isotopic ratios of the magnetite-series and ilmenite-series granitoids of the Sierra Nevada batholith–a reconnaissance study. GEOLOGY 17, 788–91.
Kay, E. A. 1985. Hydrothermal mineralization and alteration of the Lagalochan Au-Cu-Mo prospect W. Scotland. Ph.D. thesis (unpubl.), University of London.
Land, L. S. 1983. The application of stable isotopes to studies of the origin of dolomite and to problems of diagenesis of clastic sediments. In Arthur, M. A. (ed.) Stable isotopes in sedimentary geology SEPM SHORT COURSE 10, 4.14.22.
Laouar, R., Boyce, A.J, Fallick, A. E. & Leake, B. E. 1990. A sulphurisotope study on selected Caledonian granites of Britain and Ireland. GEOL J 25, 359–69.
Longstaffe, F. J. 1989, Stable isotopes as tracers in clastic diagenesis. In Hutcheon, I. E. (ed.), Short course in burial diagenesis, MINERAL ASSOC CAN SHORT COURSE SER 15, 201–77.
Lowell, J. D. & Guilbert, J. M. 1970. Lateral and vertical alteration-mineralization zoning in porphyry ore deposits. ECON GEOL 65, 373408.
Lowry, D. 1986. The geology of the Kilmelford Region of Western Argyllshire, with special reference to Late Caledonian intrusives and associated hydrothermal alteration. B.Sc. dissertation (unpubl.), College of St. Paul & St.Mary, Cheltenham, 125pp.
Lowry, D. 1991. The genesis of Late Caledonian granitoid-related mineralization in Northern Britain. Ph.D. thesis (unpubl.). University of St Andrews, 625pp.
McCrea, J. M. 1950. On the isotopic chemistry of carbonates and a palaeotemperature scale. J CHEM PHYS 18, 849–57.
McMillan, W. J. & Panteleyev, A. 1980. Ore Deposit Models—1. Porphyry Copper Deposits. GEOSCIE 7, 5263.
Murowchick, J. B. & Barnes, H. L. 1987. Effects of temperature and degree of supersaturation on pyrite morphology. AM MINER 72, 1241–50.
Nash, J. T. 1976. Fluid inclusion petrology–data from porphyry copper deposits and applications to exploration. USGS PROF PAP 907–D.
Ohmoto, H. 1986. Stable isotope geochemistry of ore deposits. Ch. 14. In Valley, J. W., Taylor, H. P.Jnr. & O'Neil, J. R. (eds) Stable isotopes in high temperature geological processes. MINERAL SOCAM, REV IN MINERAL 16, 491559.
Ohmoto, H. & Rye, R. O. 1979. Isotopes of sulfur and carbon. Ch. 10 In Barnes, H. L. (ed.), Geochemistry of hydrothermal ore deposits (2nd Ed.), 509–67. New York: Wiley & Sons.
Pattison, D. R. 1989. P-T conditions and the influence of graphite on pelitic phase relations in the Ballachulish Aureole, Scotland. J PETROL 30, 1219–44.
Plant, J. A., Brown, G. C, Simpson, P. R. & Smith, R. T. 1980. Signatures of metalliferous granites in the Scottish Caledonides. TRANS INSTN MIN METALL (SECT B) 89, 198210.
Potter, R. W. II 1977. Pressure corrections for fluid inclusion homogenization temperatures based on the volumetric properties of the system NaCl-H2O. J RES USGS 5, 603–7.
Potter, R. W. II & Brown, D. L. 1977. The volumetric properties of aqueous sodium chloride solutions from 0 to 500°C at pressures up to 2000 bars based on a regression line of available data in the literature. USGS BULL 1421–C.
Rice, C. M. & Davies, B. 1979. Copper mineralization associated with an appinite pipe in Argyll, Scotland. TRANS INSTN MIN METALL (SECT B) 88, 154–60.
Rice, C. M. 1993. Mineralization associated with Caledonian intrusive activity. Ch. 3 In Pattrick, R. A. D. & Polya, D. A. (eds), Mineralization in the British Isles, 102–86.
Robinson, B. W. & Kusakabe, M. 1975. Quantitative preparation of SO2 for 34S/32S analysis from sulphides by combustion with cuprous oxide. ANAL CHEM 47, 1179–81.
Roedder, E. 1984. Fluid Inclusions. MINER SOC AM, REV IN MINERAL 12.
Rogers, G. & Dunning, G. R. 1991. Geochronology of appinite and related granitic magmatism in the W. Highlands of Scotland: constraints on the timing of transcurrent Fault movement. J GEOL SOC LONDON 148, 1727.
Sasaki, A. & Ishihara, S. 1979. Sulfur isotopic composition of the magnetite-series and ilmenite-series granitoids in Japan. CONTRIB MINERAL PETROL 68, 107–15.
Sasaki, A., Ulriksen, C. E., Sato, K. & Ishihara, S. 1984. Sulfur isotope reconnaissance of porphyry copper and manto-type deposits in Chile and the Philippines. BULL GEOL SURV JAPAN 35, 615–22.
Scott, R. A., Pattrick, R. A. D. & Polya, D. A. 1987. Sulphur isotopic and related studies on Dalradian stratabound mineralization in the Tyndrum region, Scotland. BGS Stable Isotope Report 130.
Scott, R. A., Pattrick, R. A. D. & Polya, D. A. 1991. Origin of sulphur in metamorphosed stratabound mineralisation from the Argyll Group Dalradian of Scotland. TRANS R SOC EDINBURGH: EARTH-SCI 82, 91–8.
Shelton, K. L. & Rye, D. M. 1982. Sulfur isotopic composition of ores from Mines Gaspe, Quebec: An example of sulfate-sulfide isotopic disequilibria in ore forming fluids with applications to other porphyry-type deposits. ECON GEOL 77, 1688–709.
Shepherd, T. J., Rankin, A. H. & Alderton, D. H. M. 1985. A practical guide to fluid inclusion studies. London: Blackie.
Sheppard, S. M. F. 1986. Characterization and isotopic variations in natural waters. Ch. 6. In Valley, J. W., Taylor, H. P. Jnr. & O'Neil, J. R. (eds), Stable isotopes in high temperature geological processes. MINERAL SOC AM, REV IN MINERAL 16, 165–81.
Sillitoe, R. H. 1988. Gold and silver deposits in porphyry systems. In Schafer, R. W., Cooper, J. J. & Vikre, P. G. (eds) Bulk mineable precious metal deposits of the Western United States, 233–57. Nevada, Reno: Geological Society of America.
Smitheringdale, W. G. & Jensen, M. L. 1963. Sulfur isotopic composition of the Triassic igneous rocks of eastern United States. GEOCHIM ET COSMOCHIM ACTA 27, 1183–207.
C-S., So, Rye, D. M. & Shelton, K. L. 1983. Carbon, hydrogen, oxygen and sulphur isotope, and fluid inclusion study of the Weolag tungsten-molybdenum deposit, Republic of Korea: fluid histories of metamorphic and ore-forming events. ECON GEOL 78, 1551–73.
Stephens, W. E. 1988. Granitoid plutonism in the Caledonian orogen of Europe. In Harris, A. L. & Fettes, D. J. (eds), The Caledonian-Appalachian Orogen, GEOL SOC LONDO SPEC PUBL 38, 389403.
Stephens, W. E. & Halliday, A. N. 1984. Geochemical contrasts between late Caledonian granitoid plutons of northern, central and southern Scotland. TRANS R SOC EDINBURGH: EARTH SCI 75, 259–73.
Taylor, B. E. 1986. Magmatic volatiles: isotopic variation of C, H and S. Ch. 7 In Valley, J. W., Taylor, H. P. Jnr. & O'Neil, J. R. (eds) Stable isotopes in high temperature geological processes. MINERAL SOC AM, REV IN MINERAL 16, 185225.
Thirlwall, M. F. 1988. Geochronology of Late Caledonian magmatism in Northern Britain. J GEOL SOC LONDON 145, 951–67.
Tindle, A. G., Webb, P. C. & Ixer, R. A. 1987. Fluid-rock interaction and associated rare metal mineralisation in the Glen Gairn intrusive complex, Scotland. Extended abstract, ‘The Origin of Granites’ Symposium, Edinburgh.
Titley, S. R. & Beane, R. E. 1981. Porphyry Copper Deposits; Part 1. Geologic Settings, Petrology and Tectogenesis. ECON GEOL (75th Anniv. Vol.) 214–35.
Weiss, S. & Troll, G. 1989. The Ballachulish Igneous Complex, Scotland: petrography, mineral chemistry and order of crystallization in the monzodiorite-quartz diorite suite and in the granite. J PETROL 30, 1069–115.
Willan, R. C. R. & Coleman, M. L. 1983. Sulfur isotope study of the Aberfeldy barite, zinc, lead deposit and minor sulfide mineralisation in the Dalradian Metamorphic Terrain, Scotland. ECON GEOL 78, 1619–56.
Williams-Jones, A. E. & Samson, I. M. 1989. A sulfur isotope study of the granite-related Madeline Copper Deposit, Gaspe, Quebec. An example of a sedimentary sulfur source. ECON GEOL 84, 1507–14.
Zheng, Y.-F. 1990a. The effect of Rayleigh degassing of magma on sulphur isotope composition: A quantitative evaluation. TERRA NOVA 2, 74–8.
Zheng, Y.-F. 1990b. The selective flux of sulfur and implications for magmatic sulfur isotope fractionation. ISOTOPENPRAXIS 26, 371–4.
Zhou, J-X. 1985. Geochemistry of the Kilmelford intrusives, west Scotland, in relation to the Caledonian orogeny. Ph.D. thesis (unpubl), University of London.
Zhou, J-X. 1988. A gold- and silver-bearing subvolcanic centre in the Scottish Caledonides near Lagalochan, Argyllshire. J GEOL SOC LONDON 145, 225–34.

Keywords

Related content

Powered by UNSILO

Genesis of porphyry and plutonic mineralisation systems in metaluminous granitoids of the Grampian Terrane, Scotland

  • David Lowry (a1), Adrian J. Boyce (a2), Anthony E. Fallick (a2) and W. Edryd Stephens (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.