Hostname: page-component-586b7cd67f-gb8f7 Total loading time: 0 Render date: 2024-11-22T06:36:50.224Z Has data issue: false hasContentIssue false
  • English
  • Français

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

Published online by Cambridge University Press:  03 November 2011

David Lowry ,
Adrian J. Boyce ,
Anthony E. Fallick  and
W. Edryd Stephens
David Lowry
Affiliation:
Department of Geology, University of St Andrews, Fife KY169ST, UK
Adrian J. Boyce
Affiliation:
Isotope Geology Unit, Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow G75 OQU, UK
Anthony E. Fallick
Affiliation:
Isotope Geology Unit, Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow G75 OQU, UK
W. Edryd Stephens
Affiliation:
Department of Geology, University of St Andrews, Fife KY169ST, UK
Get access Rights & Permissions [Opens in a new window]

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.

Keywords

Caledonianstable isotopefulid inclusionsulphide mineralogywallrock alterationmagmatic fluid
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 85 , Issue 3 , 1994 , pp. 221 - 237
Copyright
Copyright © Royal Society of Edinburgh 1994

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

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.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
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, 39–47.Google Scholar
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.Google Scholar
Ellis, R. A., Marsden, G. R. & Fortey, N. J. 1978. Disseminated sulphide mineralization at Garbh Achadh, Argyllshire, Scotland. BGS MINER RECONNAISSANCE REP 23.Google Scholar
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, 47–51.Google Scholar
Fallick, A. E., Jocelyn, J., Donnelly, T., Guy, M. & Behan, C. (1985). Origin of agates in volcanic rocks fro Scotland. NATURE 313, 672–4.CrossRefGoogle Scholar
Field, C. W. 1973. Sulfur isotope abundances in hydrothermal sulfatesulfide assemblages of the American Cordillera. GEOL SOC AM, ABS WITH PROGS 10, 619.Google Scholar
Field, C. W. & Gustafson, L. B. 1976. Sulfur isotopes in the porphyry copper deposit at El Salvador, Chile. ECON GEOL 71, 1533–48.CrossRefGoogle Scholar
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.Google Scholar
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.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
Haas, J. L. 1971. The effect of salinity on the maximum thermal gradient of a hydrothermal systemat hydrostatic pressure. ECON GEOL 66, 940–46.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
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, 63–71.CrossRefGoogle Scholar
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, 15–21.Google Scholar
Harmon, R. S. & Halliday, A. N. 1980. Oxygen and strontium isotope relationships in the British Late Caledonian granites. NATURE 283, 21–5.CrossRefGoogle Scholar
Haslam, H. W. & Kimbell, G. S. 1981. Disseminated copper-molybdenum mineralisation near Ballachulish, Highland Region. BGS MINER RECONNAISSANCE PROG REP 43.Google Scholar
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.Google Scholar
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.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
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, 788–91.2.3.CO;2>CrossRefGoogle Scholar
Kay, E. A. 1985. Hydrothermal mineralization and alteration of the Lagalochan Au-Cu-Mo prospect W. Scotland. Ph.D. thesis (unpubl.), University of London.Google Scholar
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, 4.1–4.22.Google Scholar
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.CrossRefGoogle Scholar
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.Google Scholar
Lowell, J. D. & Guilbert, J. M. 1970. Lateral and vertical alteration-mineralization zoning in porphyry ore deposits. ECON GEOL 65, 373–408.CrossRefGoogle Scholar
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.Google Scholar
Lowry, D. 1991. The genesis of Late Caledonian granitoid-related mineralization in Northern Britain. Ph.D. thesis (unpubl.). University of St Andrews, 625pp.Google Scholar
McCrea, J. M. 1950. On the isotopic chemistry of carbonates and a palaeotemperature scale. J CHEM PHYS 18, 849–57.CrossRefGoogle Scholar
McMillan, W. J. & Panteleyev, A. 1980. Ore Deposit Models—1. Porphyry Copper Deposits. GEOSCIE 7, 52–63.Google Scholar
Murowchick, J. B. & Barnes, H. L. 1987. Effects of temperature and degree of supersaturation on pyrite morphology. AM MINER 72, 1241–50.Google Scholar
Nash, J. T. 1976. Fluid inclusion petrology–data from porphyry copper deposits and applications to exploration. USGS PROF PAP 907–D.Google Scholar
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, 491–559.Google Scholar
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.Google Scholar
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.CrossRefGoogle Scholar
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, 198–210.Google Scholar
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.Google Scholar
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.Google Scholar
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.Google Scholar
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.Google Scholar
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.CrossRefGoogle Scholar
Roedder, E. 1984. Fluid Inclusions. MINER SOC AM, REV IN MINERAL 12.Google Scholar
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, 17–27.CrossRefGoogle Scholar
Sasaki, A. & Ishihara, S. 1979. Sulfur isotopic composition of the magnetite-series and ilmenite-series granitoids in Japan. CONTRIB MINERAL PETROL 68, 107–15.CrossRefGoogle Scholar
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.Google Scholar
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.Google Scholar
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.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
Shepherd, T. J., Rankin, A. H. & Alderton, D. H. M. 1985. A practical guide to fluid inclusion studies. London: Blackie.Google Scholar
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.CrossRefGoogle Scholar
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.Google Scholar
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.CrossRefGoogle Scholar
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.Google Scholar
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, 389–403.Google Scholar
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.CrossRefGoogle Scholar
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, 185–225.Google Scholar
Thirlwall, M. F. 1988. Geochronology of Late Caledonian magmatism in Northern Britain. J GEOL SOC LONDON 145, 951–67.CrossRefGoogle Scholar
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.Google Scholar
Titley, S. R. & Beane, R. E. 1981. Porphyry Copper Deposits; Part 1. Geologic Settings, Petrology and Tectogenesis. ECON GEOL (75th Anniv. Vol.) 214–35.Google Scholar
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.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
Zheng, Y.-F. 1990a. The effect of Rayleigh degassing of magma on sulphur isotope composition: A quantitative evaluation. TERRA NOVA 2, 74–8.CrossRefGoogle Scholar
Zheng, Y.-F. 1990b. The selective flux of sulfur and implications for magmatic sulfur isotope fractionation. ISOTOPENPRAXIS 26, 371–4.Google Scholar
Zhou, J-X. 1985. Geochemistry of the Kilmelford intrusives, west Scotland, in relation to the Caledonian orogeny. Ph.D. thesis (unpubl), University of London.Google Scholar
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.CrossRefGoogle Scholar