Hostname: page-component-8448b6f56d-mp689 Total loading time: 0 Render date: 2024-04-20T02:50:50.989Z Has data issue: false hasContentIssue false
  • English
  • Français

Late Caledonian transpression and the structural controls on pluton construction; new insights from the Omey Pluton, western Ireland

Published online by Cambridge University Press:  10 December 2015

William McCarthy ,
R. John Reavy ,
Carl T. Stevenson  and
Michael S. Petronis
William McCarthy*
Affiliation:
Department of Earth & Environmental Sciences, University of St Andrews, St Andrews, Fife, KY16 9AL, UK. Email: wm37@st-andrews.ac.uk
R. John Reavy
Affiliation:
School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
Carl T. Stevenson
Affiliation:
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
Michael S. Petronis
Affiliation:
Environmental Geology, Natural Resource Management Department, New Mexico Highlands University, Las Vegas NM 87701, USA
*
*Corresponding author
Get access Rights & Permissions [Opens in a new window]

Abstract

The Galway Granite Complex is unique among the British and Irish Caledonian granitoid terranes, as it records punctuated phases of magmatism from ∼425–380 Ma throughout the latest phase of the Caledonian Orogeny. Remapping of the Omey Pluton, the oldest member of this suite, has constrained the spatial distribution and contact relationships of the pluton's three main facies relative to the nature of the host rock structure. The external contacts of the pluton are mostly concordant to the limbs and hinge of the Connemara Antiform. New AMS data show that a subtle concentric outward dipping foliation is present, and this is interpreted to reflect pluton inflation during continued magma ingress. Combined field, petrographic and AMS data show that two sets of shear zones (NNW–SSE and ENE–WSW) cross-cut the concentric foliation, and that these structures were active during the construction of the pluton. We show that regional sinistral transpression at ∼420 Ma would have caused dilation along the intersection of these two fault sets, and suggest that this facilitated centralised magma ascent. Lateral emplacement was controlled by the symmetry of the Connemara Antiform to ultimately produce a discordant phacolith. We propose that regional sinistral transpression at ∼420 Ma influenced the siting of smaller intrusions over NNW–SSE faults, and that the later onset of regional transtension caused larger volumes of magma to intrude along the E–W Skird Rocks Fault at ∼400 Ma.

Keywords

Anisotropy of magnetic susceptibilityanticlineascent and emplacementCaledonian graniteflowfoldGalway Granite Complexmicrostructurephacolithtranspression
Type
Articles
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 106 , Issue 1 , March 2015 , pp. 11 - 28
Copyright
Copyright © The Royal Society of Edinburgh 2015 

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

9. References

Ahmed-Said, Y. & Leake, B. E. 1996. The conditions of metamorphism of a grossular–wollastonite vesuvianite skarn from the Omey Granite, Connemara, western Ireland, with special reference to the chemistry of vesuvianite. Mineralogical Magazine 60, 541–50.Google Scholar
Alimohammadian, H., Hamidi, Z., Aslani, A., Shahidi, A., Cifelli, F. & Mattei, M. 2013. A tectonic origin of magnetic fabric in the Shemshak Group from Alborz Mts. (northern Iran). Journal of Asian Earth Sciences 73, 419–28.Google Scholar
Badley, M. E. 1976. Stratigraphy, structure and metamorphism of Dalradian rocks of the Maumturk Mountains, Connemara, Ireland. Journal of the Geological Society, London 132, 509–20.Google Scholar
Baxter, S., Graham, N. T., Feely, M., Reavy, R. J. & Dewey, J. F. 2005. A microstructural and fabric study of the Galway Granite, Connemara, western Ireland. Geological Magazine 142, 81–95.Google Scholar
Benn, K., Paterson, S. R., Lund, S. P., Pignotta, G. S. & Kruse, S. 2001. Magmatic fabrics in batholiths as markers of regional strains and plate kinematics: example of the Cretaceous Mt. Stuart batholith. Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy 26, 343–54.Google Scholar
Brown, M. & Solar, G. S. 1998. Granite ascent and emplacement during contractional deformation in convergent orogens. Journal of Structural Geology 20, 1365–93.Google Scholar
Brown, P. E., Ryan, P. D., Soper, N. J. & Woodcock, N. H. 2008. The Newer Granite problem revisited: a transtensional origin for the Early Devonian Trans-Suture Suite. Geological Magazine 145, 235–56.Google Scholar
Buchwaldt, R., Kroner, A., Toulkerides, T., Todt, W. & Feely, M. 2001. Geochronology and Nd–Sr systematics of late Caledonian granites in western Ireland: new implications for the Caledonian Orogeny. Geological Society of America Abstracts with Programs 33(1), A32.Google Scholar
Cobbing, E. J. 1969. The Geology of the District Northwest of Clifden, Co. Galway. Proceedings of the Royal Irish Academy. Section B: Biological, Geological and Chemical Science 67, 303–25.Google Scholar
Corry, C. E. 1988. Laccoliths: Mechanics of emplacement and growth. Geological Society of America Special Paper 220, 3–10.Google Scholar
Crowley, Q. & Feely, M. 1997. New perspectives on the order and style of granite emplacement in the Galway Batholith, western Ireland. Geological Magazine 134, 539–48.Google Scholar
Desouky, M. E., Feely, M. & Mohr, P. 1996. Diorite-granite magma mingling and mixing along the axis of the Galway Granite batholith, Ireland. Journal of the Geological Society, London 153, 361–74.Google Scholar
Dewey, J. F. & Strachan, R. A. 2003. Changing Silurian–Devonian relative plate motion in the Caledonides: sinistral transpression to sinistral transtension. Journal of the Geological Society, London 160, 219–29.Google Scholar
Elias, E. M., Macintyre, R. M. & Leake, B. E. 1988. The cooling history of Connemara, western Ireland, from K-Ar and Rb-Sr age studies. Journal of the Geological Society, London 145, 649–60.Google Scholar
Feely, M., Coleman, D., Baxter, S. & Miller, B. 2003. U–Pb zircon geochronology of the Galway Granite, Connemara, Ireland: implications for the timing of late Caledonian tectonic and magmatic events and for correlations with Acadian plutonism in New England. Atlantic Geology 39, 175–84.Google Scholar
Feely, M., Selby, D., Conliffe, J. & Judge, M. 2007. Re–Os geochronology and fluid inclusion microthermometry of molybdenite mineralisation in the late-Caledonian Omey Granite, western Ireland. Applied Earth Science 116, 143–49.Google Scholar
Feely, M., Selby, D., Hunt, J. & Conliffe, J. 2010. Long-lived granite-related molybdenite mineralization at Connemara, western Irish Caledonides. Geological Magazine 147, 886–94.Google Scholar
Ferguson, C. C. & Al-Ameen, S. I. 1986. Geochemistry of Dalradian pelites from Connemara, Ireland: new constraints on kyanite genesis and conditions of metamorphism. Journal of the Geological Society, London 143, 237–52.Google Scholar
Ferguson, C. C. & Harvey, P. K. 1979. Thermally overprinted Dalradian rocks near Cleggan, Connemara Western Ireland. Proceedings of the Geologists' Association 90, 43–50.Google Scholar
Friedrich, A. M., Hodges, K. V, Bowing, S. A. & Martin, M. W. 1999a. Geochronological constraints on the magmatic, metamorphic and thermal evolution of the Connemara Caledonides, western Ireland. Journal of the Geological Society, London 156, 1217–30.Google Scholar
Friedrich, A. M., Bowring, S. A., Martin, M. W. & Hodges, K. V. 1999b. Short-lived continental magmatic arc at Connemara, western Irish Caledonides: implications for the age of the Grampian orogeny. Geology 27, 27–30.Google Scholar
Graham, N. T., Feely, M. & Callaghan, B. 2000. Plagioclase-rich microgranular inclusions from the late-Caledonian Galway Granite, Connemara, Ireland. Mineralogical Magazine 64, 113–20.Google Scholar
Harker, A. 1909. The Natural History of Igenous Rocks. New York: Macmillan. 384 pp.Google Scholar
Hutton, D. H. W. 1988. Granite emplacement mechanisms and tectonic controls: inferences from deformation studies. Transactions of the Royal Society of Edinburgh: Earth Sciences 79, 245–55.Google Scholar
Hutton, D. H. W. 2009. Insights into magmatism in volcanic margins: bridge structures and a new mechanism of basic sill emplacement – Theron Mountains, Antarctica. Petroleum Geoscience 15, 269–78.Google Scholar
Hutton, D. H. W. & Alsop, G. I. 1996. The Caledonian strike-swing and associated lineaments in NW Ireland and adjacent areas: sedimentation, deformation and igneous intrusion patterns. Journal of the Geological Society, London 153, 345–60.Google Scholar
Hutton, D. H. W. & Siegesmund, S. 2001. The Ardara Granite: Reinflating the Balloon Hypothesis. Zeitschrift der Deutschen Geologischen Gesellschaft 152, 309–23.Google Scholar
Jacques, J. M. & Reavy, R. J. 1994. Caledonian plutonism and major lineaments in the SW Scottish Highlands. Journal of the Geological Society, London 151, 955–1060.Google Scholar
Jelinek, V. 1981. Characterization of the magnetic fabric of rocks. Tectonophysics 79, T63–T67.Google Scholar
Just, J. & Kontny, A. 2011. Thermally induced alterations of minerals during measurements of the temperature dependence of magnetic susceptibility: a case study from the hydrothermally altered Soultz-sous-Forêts granite, France. International Journal of Earth Sciences 101, 819–39.Google Scholar
Kilburn, C., Shackleton, R. M. & Pitcher, W. S. 1965. The stratigraphy and origin of the portaskaig boulder bed series (Dalradian). Geological Journal 4, 343–60.Google Scholar
Kinahan, G. H. 1869. Explanation to accompany Sheet 105 with that portion of Sheet 114 that lies north of Galway Bay. Memoir of the Geological Survey of Ireland, Dublin.Google Scholar
Kinahan, G. H. 1878. Explanatory memoir to accompany Sheets 93 and 94, with the adjoining portions of Sheets 83, 84, and 103, of the maps of the Geological Survey of Ireland. Memoir of the Geological Survey of Ireland, Dublin.Google Scholar
Kligfield, R., Owens, W. H. & Lowrie, W. 1981. Magnetic susceptibility anisotropy, strain, and progressive deformation in Permian sediments from the Maritime Alps (France). Earth and Planetary Science Letters 55, 181–89.Google Scholar
Leake, B. E. 1974. The crystallization history and mechanism of emplacement of the western part of the Galway Granite, Connemara, Western Ireland. Mineralogical Magazine 39, 498–513.Google Scholar
Leake, B. E. 1986. The geology of SW Connemara, Ireland: a fold and thrust Dalradian and metagabbroic-gneiss complex. Journal of the Geological Society, London 143, 221–36.Google Scholar
Leake, B. E. 2008. Mechanism of emplacement and crystallisation history of the northern margin and centre of the Galway Granite, western Ireland. Transactions of the Royal Society of Edinburgh: Earth Sciences 97(for 2006), 1–23.Google Scholar
Leake, B. E. 2011. Stoping and the mechanisms of emplacement of the granites in the Western Ring Complex of the Galway granite batholith, western Ireland. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 102, 1–16.Google Scholar
Leake, B. E., Tanner, P. W. G., Singh, D. & Halliday, A. N. 1983. Major southward thrusting of the Dalradian rocks of Connemara, western Ireland. Nature 305, 210–13.Google Scholar
Leake, B. E. & Tanner, G. P. W. 1994. The Geology of the Dalradian and Associated Rocks of Connemara, Western Ireland. Dublin: Royal Irish Academy. 96 pp.Google Scholar
Leggo, P. J., Compston, W. & Leake, B. E. 1966. The geochronology of the Connemara granites and its bearing on the antiquity of the Dalradian Series. Quarterly Journal of the Geological Society, London 122, 91–116.Google Scholar
Long, C. B. & McConnell, B. 1995. Bedrock Geology, 1:100,000 Series. Geological Survey of Ireland Sheet 10.Google Scholar
Madden, J. S. 1987. Gamma-ray spectrometric studies of the main Galway Granite, Connemara, western Ireland. PhD Thesis, National University of Ireland.Google Scholar
Magee, C., Stevenson, C. T. E., Driscoll, B. O. & Petronis, M. S. 2012. Local and regional controls on the lateral emplacement of the Ben Hiant Dolerite intrusion, Ardnamurchan (NW Scotland). Journal of Structural Geology 39, 66–82.Google Scholar
Max, M. D., Long, C. B. & Geoghegan, M. A. 1978. The Galway Granite. Bulletin of the Geological Survey of Ireland 2, 431–51.Google Scholar
McCarthy, W. 2013. An evaluation of orogenic kinematic evolution utilizing crystalline and magnetic anisotropy in granitoids. PhD Thesis, University College Cork, National University of Ireland.Google Scholar
McCarthy, W., Petronis, M. S., Reavy, R. J. & Stevenson, C. T. E. 2015. Distinguishing diapirs from inflated plutons; an integrated rock magnetic, magnetic fabric and structural study on the Roundstone Pluton, western Ireland. Journal of the Geological Society, London 172, 550–65.Google Scholar
Meere, P. A. & Mulchrone, K. F. 2006. Timing of deformation within Old Red Sandstone lithologies from the Dingle Peninsula, SW Ireland. Journal of the Geological Society, London 163, 461–69.Google Scholar
Molyneux, S. J. & Hutton, D. H. W. 2000. Evidence for significant granite space creation by the ballooning mechanism: The example of the Ardara pluton, Ireland. Geological Society of America Bulletin 112, 1543–58.Google Scholar
Neilson, J. C., Kokelaar, B. P. & Crowley, Q. G. 2009. Timing, relations and cause of plutonic and volcanic activity of the Siluro-Devonian post-collision magmatic episode in the Grampian Terrane, Scotland. Journal of the Geological Society, London 166, 545–61.Google Scholar
Owens, W. H. 1974. Mathematical model studies on factors affecting the magnetic anisotropy of deformed rocks. Tectonophysics 24, 115–31.Google Scholar
Owens, W. H. 2000. Statistical analysis of normalized and unnormalized second rank tensor data, with application to measurements of anisotropy of magnetic susceptibility. Geophysical Research Letters 27, 2985–88.Google Scholar
Parés, J. M. & van der Pluijm, B. A. 2002. Evaluating magnetic lineations (AMS) in deformed rocks. Tectonophysics 350, 283–98.Google Scholar
Passchier, C. W. & Trouw, R. A. J. 2005. Microtectonics. Berlin Heidelberg New York: Springer-Verlag. 366 pp.Google Scholar
Pe-Piper, G., Piper, D. J. W. & Matarangas, D. 2002. Regional implications of geochemistry and style of emplacement of Miocene I-type diorite and granite, Delos, Cyclades, Greece. Lithos 60, 47–66.Google Scholar
Petronis, M. S., Hacker, D. B., Holm, D. K., Geissman, J. W. & Harlan, S. S. 2004. Magmatic flow paths and palaeomagnetism of the Miocene Stoddard Mountain laccolith, Iron Axis region, Southwestern Utah, USA. Geological Society, London, Special Publications 238, 251–83.Google Scholar
Petronis, M. S., Driscoll, B. O., Stevenson, C. T. E. & Reavy, R. J. 2012. Controls on emplacement of the Caledonian Ross of Mull Granite, NW Scotland: Anisotropy of magnetic susceptibility and magmatic and regional structures. Geological Society of America Bulletin 124(5/6), 906–27.Google Scholar
Pitcher, W. S. 1998. The Nature and Origin of Granite, 2nd edition. London: Chapman & Hall. 387 pp.Google Scholar
Pitcher, W. S. & Bussell, M. A. 1977. Structural control of batholithic emplacement in Peru: a review. Journal of the Geological Society, London 133, 249–55.Google Scholar
Richey, J. E. 1932. Tertiary ring structures in Britain. Transactions of the Geological Society of Glasgow 19, 42–140.Google Scholar
Ryan, P. D., Snyderj, D. B., England, R. W., Soper, N. J., Snyder, D. B. & Hutton, D. H. W. 1995. The Antrim–Galway Line: a resolution of the Highland Border Fault enigma of the Caledonides of Britain and Ireland. Geological Magazine 132, 171–84.Google Scholar
Schofield, N., Heaton, L., Holford, S. P., Archer, S. G., Jackson, C. A. L. & Jolley, D. W. 2012. Seismic imaging of ‘broken bridges’: linking seismic to outcrop-scale investigations of intrusive magma lobes. Journal of the Geological Society, London 169, 421–26.Google Scholar
Selby, D., Creaser, R. A. & Feely, M. 2004. Accurate and precise Re–Os molybdenite dates from the Galway Granite, Ireland. Critical comment on ‘Disturbance of the Re–Os chronometer of molybdenites from the late-Caledonian Galway Granite, Ireland, by hydrothermal fluid circulation’. Geochemical Journal 38, 291–94.Google Scholar
Soper, N. J. & Woodcock, N. H. 2003. The lost Lower Old Red Sandstone of England and Wales: a record of post-Iapetan flexure or Early Devonian transtension? Geological Magazine 140, 627–47.Google Scholar
Stevenson, C. T. E., Hutton, D. H. W. & Price, A. R. 2008. The Trawenagh Bay Granite and a new model for the emplacement of the Donegal Batholith. Transactions of the Royal Society of Edinburgh: Earth Sciences 97(for 1996), 455–77.Google Scholar
Stone, P., Kimbell, G. S. & Henney, P. J. 1997. Basement control on the location of strike-slip shear in the Southern Uplands of Scotland. Journal of the Geological Society, London 154, 141–44.Google Scholar
Suzuki, K., Feely, M. & O'Reilly, C. 2001. Disturbance of the Re–Os chronometer of molybdenites from the late-Caledonian Galway Granite, Ireland, by hydrothermal fluid circulation. Geochemical Journal 35, 29–35.Google Scholar
Tanner, P. W. G., Dempster, T. J. & Dickin, A. P. 1989. Short Paper: Time of docking of the Connemara terrane with the Delaney Dome Formation, western Ireland. Journal of the Geological Society, London 146, 389–92.Google Scholar
Tarling, D. H. & Hrouda, F. (eds) 1993. The Magnetic Anisotropy of Rocks. London: Chapman & Hall. 217 pp.Google Scholar
Townend, R. 1966. The geology of some granite plutons from western Connemara, Co. Galway. Proceedings of the Royal Irish Academy 65 Section, 157–202.Google Scholar
Treloar, P. J. 1977. The stratigraphy, geochemistry and metamorphism of the rocks of the Recess area, Connemara, Eire. PhD Thesis, University of Glasgow, UK.Google Scholar
Treloar, P. J. 1982. The stratigraphy and structure of the rocks of the Lissoughter area, Connemara. Proceedings of the Royal Irish Academy 82 Section, 83–107.Google Scholar
Valley, P. M., Hanchar, J. M. & Whitehouse, M. J. 2011. New insights on the evolution of the Lyon Mountain Granite and associated Kiruna-type magnetite-apatite deposits, Adirondack Mountains, New York State. Geosphere 7, 357–89.Google Scholar
Vance, A. J. 1969. On Synneusis. Contributions to Mineralogy and Petrology 24, 7–29.Google Scholar
Vernon, R. H. 2004. A practical guide to Rock Microstructure. Cambridge, UK: Cambridge University Press. 594 pp.Google Scholar
Woodcock, N. H., Soper, N. J. & Strachan, R. A. 2007. A Rheic cause for the Acadian deformation in Europe. Journal of the Geological Society, London. 164 1023–36.Google Scholar
Wright, P. C. 1964. The petrology, chemistry and structure of the Galway granite of the Carna area, County Galway. Proceedings of the Royal Irish Academy 62 Section, 239–64.Google Scholar
Supplementary material: PDF

McCarthy supplementary material

Appendix

Download McCarthy supplementary material(PDF)
PDF 382.3 KB