Hostname: page-component-78c5997874-ndw9j Total loading time: 0 Render date: 2024-11-14T01:29:20.677Z Has data issue: false hasContentIssue false
  • English
  • Français

Caledonian strike-slip terrane accretion in W. Ireland: insights from very low-grade metamorphism (illite–chlorite crystallinity and b0 parameter)

Published online by Cambridge University Press:  05 October 2009

A. H. N. RICE  and
D. M. WILLIAMS
A. H. N. RICE*
Affiliation:
University of Vienna, Department of Geodynamics and Sedimentology, Althanstraße 14, 1090 Vienna, Austria
D. M. WILLIAMS
Affiliation:
Department of Earth and Ocean Sciences, National University of Ireland, Galway, Ireland
*
*Author for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Analysis of pelites with detrital white-micas in the Clew Bay–Galway Bay segment of the Irish Caledonides indicates that b0 data from whole-rock and < 2 μm fractions generally show differences smaller than the errors of the method, irrespective of (001) illite crystallinity values, probably due to metamorphic recrystallization. Intermediate pressure metamorphism of the Ordovician–Silurian Clew Bay Group indicates slow subduction, allowing partial thermal re-equilibration before exhumation. In contrast, the Croagh Patrick Group Laurentian shelf-sediments underwent high-pressure alteration, suggesting rapid subduction/exhumation, synchronous with strike-slip faulting. The Murrisk Group, which underwent high-intermediate pressure metamorphism in an Ordovician back-arc, forms a separate terrane to the Croagh Patrick Group to the north and also to the Ordovician Lough Nafooey and Tourmakeady groups and Rosroe Formation in the south, in which low-intermediate pressure alteration occurred. These, together with the Silurian North Galway Group, may have undergone heating due to movement over or deposition on the hot Gowlaun Detachment as the Connemara Dalradian was exhumed. The South Connemara Group also underwent a high-pressure alteration, consistent with its inferred subduction environment. Evidence of contact alteration, due to known or inferred buried late- to post-Caledonian granitoid plutons, has been found in the Clew Bay, Louisburg–Clare Island, Croagh Patrick, Murrisk and South Connemara groups. These show evidence of lower-pressure alteration than the surrounding country-rocks.

Keywords

very low-grade metamorphismclay mineralsb0 spacingillite crystallinitychlorite crystallinityterranesIrelandCaledonides
Type
Original Article
Information
Geological Magazine , Volume 147 , Issue 2 , March 2010 , pp. 281 - 298
Copyright
Copyright © Cambridge University Press 2009

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

Árkai, P., Faryad, S. W., Vidal, O. & Balogh, K. 2003. Very low-grade metamorphism of sedimentary rocks of the Meliata unit, Western Carpathians, Slovakia: implications of phyllosilicate characteristics. International Journal of Earth Sciences 92, 68–85.CrossRefGoogle Scholar
Bickle, M. J., Kidd, R. G. W. & Nisbet, E. 1972. The Silurian of the Croagh Patrick range, Co. Mayo. Scientific Proceedings of the Royal Dublin Society 4A, 231–49.Google Scholar
Chew, D. M., Daly, J. S., Page, L. M. & Kennedy, M. J. 2003. Grampian orogenesis and the development of blueschist-facies metamorphism in western Ireland. Journal of the Geological Society, London 160, 911–24.CrossRefGoogle Scholar
Clift, P. D. & Ryan, P. D. 1994. Geochemical evolution of an Ordovician island arc, South Mayo, Ireland. Journal of the Geological Society, London 151, 329–42.CrossRefGoogle Scholar
Crowley, Q. & Feely, M. 1997. New perspectives on the order and style of granite emplacement in the Galway Batholith, western Ireland. Journal of the Geological Society, London 134, 539–48.Google Scholar
Dewey, J. F. & Mange, M. 1999. Petrology of Ordovician and Silurian sediments in the western Irish Caledonides: tracers of short-lived Ordovician continent-arc collision orogeny and the evolution of the Laurentian Appalachian–Caledonian margins. In Continental Tectonics (eds MacNiocall, C. & Ryan, P. D.), pp. 55–108. Geological Society of London, Special Publication no. 164.Google Scholar
Dewey, J. F. & Ryan, P. D. 1990. The Ordovician evolution of the South Mayo Trough, western Ireland. Tectonics 9, 887–901.CrossRefGoogle Scholar
Dewey, J. F. & Ryan, P. D. 2004. The South Connemara Group reinterpreted: a subduction–accretion complex in the Caledonides of Galway Bay, western Ireland. Journal of Geodynamics 37, 513–29.Google Scholar
Dewey, J. F. & Shackleton, R. M. 1984. A model for the evolution of the Grampian tract in the early Caledonides and Appalachians. Nature 312, 115–21.CrossRefGoogle Scholar
Draut, A. E. & Clift, P. D. 2001. Geochemical evolution of arc magmatism during arc–continent collision, South Mayo, Ireland. Geology 29, 543–6.2.0.CO;2>CrossRefGoogle Scholar
Evans, D. H. 1996. Ugooloceras oblatum gen. and sp. Nov., an annulate orthocerid (orthocerida, nautiloidea) from the Llanvirn series of County Mayo. Irish Journal of Earth Sciences 15, 71–6.Google Scholar
Ffrench, G. D. & Williams, D. M. 1984. The sedimentology of the South Connemara Group, western Ireland – a possible Ordovician trench-fill sequence. Geological Magazine 121, 505–14.CrossRefGoogle Scholar
Frey, M. 1987. Low temperature metamorphism. London: Blackie, 351 pp.Google Scholar
Graham, J. R., Leake, B. E. & Ryan, P. D. 1989. The Geology of South Mayo, Western Ireland. Geological Society of London, Special Report. Edinburgh: Scottish Academic Press, 75 pp.Google Scholar
Grasemann, B. & Dunkl, I. 2003. Effects of the geometry of normal faulting on the near surface heat flow during extension: the example of the Rechnitz Metamorphic Core Complex (Austria). Mitteilungen der Österreichischen Geologischen Gesellschaft 93, 87–103.Google Scholar
Guidotti, C. V. & Sassi, F. P. 1986. Classification and correlation of metamorphic facies series by means of muscovite b0 data from low-grade metapelites. Neues Jahrbuch für Mineralogie, Abhandlungen 153, 363–80.Google Scholar
Higgs, K. T. & Williams, D. M. 2001. A Silurian microflora from the Ballytoohy Formation (upper Clew Bay Complex) of Clare Island. In New Survey of Clare Island, Volume 2: Geology (ed. Graham, J. R.), pp. 19–34. Dublin: Royal Irish Academy.Google Scholar
Johnston, J. D. & Phillips, W. E. A. 1995. Terrane amalgamation in the Clew Bay region, west of Ireland. Geological Magazine 132, 485–501.CrossRefGoogle Scholar
Kemp, A. E. S. & Merriman, R. J. 2008. Polyphase low-grade metamorphism of the Ingleton Group, northern England, UK: a case study of metamorphic inversion in a mudrock sequence. Geological Magazine 146, 237–51.CrossRefGoogle Scholar
Kemp, A. E. S., Oliver, G. H. S. & Baldwin, J. R. 1985. Low-grade metamorphism and accretion tectonics: Southern Uplands terrain, Scotland. Mineralogical Magazine 49, 335–44.CrossRefGoogle Scholar
Maguire, C. K. & Graham, J. R. 1996. Sedimentation and palaeogeographical significance of the Silurian rocks of the Louisburg–Clare Island succession, western Ireland. Transactions of the Royal Society of Edinburgh: Earth Sciences 86, 132–6.Google Scholar
Max, M. D. 1989. The Clew Bay Group: a displaced terrane of Highland Border Group rocks (Cambro-Ordovician) in Northwest Ireland. Geological Journal 24, 1–17.CrossRefGoogle Scholar
Max, M. D., Rex, D. & Winchester, J. A. 1988. The Farnacht Formation along the south side of the Clew Bay Fault Zone, Western Ireland: its chemistry and age of metamorphism. Geological Journal 23, 249–60.CrossRefGoogle Scholar
Merriman, R. J. & Frey, M. 1999. Patterns of very low-grade metamorphism in metapelitic rocks. In Low-grade metamorphism (eds Frey, M. & Robinson, D.), pp. 61–107. Oxford: Blackwell.Google Scholar
Merriman, R. J. & Roberts, B. 2001. Low-grade metamorphism in the Scottish Southern Uplands terrane: deciphering the patterns of accretionary burial, shearing and cryptic aureoles. Transactions of the Royal Society of Edinburgh: Earth Sciences 91, 521–37.CrossRefGoogle Scholar
Murphy, F. C., Anderson, T. B., Daly, J. S., Gallager, V., Graham, J. R., Harper, D. A. T., Johnston, J. D., Kennan, P. S., Kennedy, M. J., Long, C. B., Morris, J. H., O'Keeffe, W. G., Parkes, M., Ryan, P. D., Sloan, R. J., Stillman, C. J., Tietzch-Tyler, D., Todd, S. P. & Wrafter, J. P. 1991. An appraisal of Caledonian suspect terranes in Ireland. Irish Journal of Earth Sciences 11, 11–41.Google Scholar
O'Connor, P. D. & Williams, D. M. 1999. Tectonic control on sedimentation during transgression: a case study from Silurian successions in Ireland and Scotland. Geological Magazine 136, 75–82.CrossRefGoogle Scholar
O'Connor, P. J. 1989. Chemistry and Rb–Sr age of the Corvock Granite, Western Ireland. Geological Survey of Ireland Bulletin 4, 99–105.Google Scholar
Offler, R., McKnight, S. & Morand, V. 1998. Tectonothermal history of the western Lachlan Fold Belt, Australia: insights from white mica studies. Journal of Metamorphic Geology 16, 531–40.CrossRefGoogle Scholar
Padan, A., Kisch, H. J. & Shagam, R. 1982. Use of the lattice parameter b0 of dioctahedral illite/muscovite for the characterisation of P/T gradients of incipient metamorphism. Contributions to Mineralogy and Petrology 79, 85–95.CrossRefGoogle Scholar
Palmer, D., Johnston, J. D., Dooley, T. & Maguire, K. 1989. The Silurian of Clew Bay, Ireland; part of the Midland Valley of Scotland. Journal of the Geological Society, London 146, 385–8.CrossRefGoogle Scholar
Phillips, W. E. A. 1974. The stratigraphy, sedimentary environments and palaeogeography of the Silurian strata of Clare Island, Co. Mayo, Ireland. Journal of the Geological Society, London 130, 19–41.CrossRefGoogle Scholar
Pudsey, C. J. 1984. Ordovician stratigraphy and sedimentology of the South Mayo inlier. Irish Journal of Earth Sciences 6, 15–45.Google Scholar
Rice, A. H. N., Bevins, R. E., Robinson, D. & Roberts, D. 1989. Thrust related metamorphic inversion in the Caledonides of Finnmark, north Norway. In Evolution of metamorphic belts (eds Daly, J. S., Cliff, R. A. and Yardley, B. W. D.), pp. 413–21. Geological Society of London, Special Publication no. 43.Google Scholar
Rice, A. H. N. & Roberts, D. 1995. Very low-grade metamorphism of Upper Proterozoic sedimentary rocks of the Rybachi and Sredni Peninsulas and Kildin Island, NW Kola region, Russia. Norges geologisk undersøkelse, Special Publication 7, 259–70.Google Scholar
Robinson, D. 1981. Metamorphic rocks of an intermediate facies series juxtaposed at the Start boundary, southwest England. Geological Magazine 18, 297–301.CrossRefGoogle Scholar
Robinson, D. 1987. Transition from diagenesis to metamorphism in extensional and collisional settings. Geology 15, 866–9.2.0.CO;2>CrossRefGoogle Scholar
Robinson, D. & Bevins, R. E. 1986. Incipient metamorphism in the Lower Palaeozoic marginal basin of Wales. Journal of Metamorphic Geology 4, 101–13.CrossRefGoogle Scholar
Ryan, K. M. & Williams, D. M. 2007. Testing the reliability of discrimination diagrams for determining the tectonic and depositional environment of ancient sedimentary basins. Chemical Geology 242, 103–25.CrossRefGoogle Scholar
Ryan, K. M., Williams, D. M., Coleman, D. S. & Loewy, S. In press. A revision of the Ordovician stratigraphy for the western Ireland Caledonides and implications for tectonic models. Geological Journal.Google Scholar
Ryan, P. D., Floyd, P. A. & Archer, J. B. 1980. The stratigraphy and petrochemistry of the Lough Nafooey Group (Tremadocian), western Ireland. Journal of the Geological Society, London 137, 443–58.CrossRefGoogle Scholar
Ryan, P. D., Sawal, V. K. & Rowlands, A. S. 1983. Ophiolite mélange separates ortho- and paratectonic Caledonides in western Ireland. Nature 301, 50–2.CrossRefGoogle Scholar
Ryan, P. D., Max, M. D. & Kelly, T. 1983. The petrochemistry of basic volcanic rocks of the South Connemara Group (Ordovician), western Ireland. Geological Magazine 120, 141–52.CrossRefGoogle Scholar
Smethurst, M. A., MacNiocaill, C. & Ryan, P. D. 1994. Oroclinal bending in the Caledonides of western Ireland. Journal of the Geological Society, London 151, 315–28.CrossRefGoogle Scholar
Stone, P. & Merriman, R. J. 2004. Basin thermal history favours an accretionary origin for the Southern Uplands terrane, Scottish Caledonides. Journal of the Geological Society, London 161, 829–36.CrossRefGoogle Scholar
Tanner, P. W. G., Dempster, T. J. & Dickin, A. P. 1989. Time of docking of the Connemara terrane with the Delaney Dome Formation, western Ireland. Journal of the Geological Society, London 146, 389–92.CrossRefGoogle Scholar
Till, R. 1974. Statistical methods for the Earth scientist. London: Macmillan, 154 pp.CrossRefGoogle Scholar
Warr, L. N. 1996. Standardized clay mineral crystallinity data from the very low-grade metamorphic facies rocks of southern New Zealand. European Journal of Mineralogy 8, 115–27.CrossRefGoogle Scholar
Warr, L. N., Primmer, T. J. & Robinson, D. 1991. Variscan very low-grade metamorphism in southwest England: a diastathermal and thrust related origin. Journal of Metamorphic Geology 9, 751–64.CrossRefGoogle Scholar
Warr, L. N. & Rice, A. H. N. 1994. Interlaboratory standardization and calibration of clay mineral crystallinity and crystallite size data. Journal of Metamorphic Geology 12, 141–52.CrossRefGoogle Scholar
Williams, A. & Curry, G. B. 1985. Lower Ordovician Brachiopoda from the Tourmakeady Limestone, Co. Mayo, Ireland. Bulletin of the British Museum (Natural History) Geology 38, 183–269.Google Scholar
Williams, D. M. 1984. The stratigraphy and sedimentology of the Ordovician Partry Group, southeastern Murrisk, Ireland. Geological Journal 19, 173–86.CrossRefGoogle Scholar
Williams, D. M. 2002. Buried oblique-slip faults in the Irish Caledonides. Geological Journal 37, 135–42.CrossRefGoogle Scholar
Williams, D. M., Armstrong, H. A. & Harper, D. A. T. 1988. The age of the South Connemara Group, Ireland, and its relationship to the Southern Uplands Zone of Scotland and Ireland. Scottish Journal of Geology 24, 279–87.CrossRefGoogle Scholar
Williams, D. M., Harkin, J., Armstrong, H. A. & Higgs, K. T. 1994. A late Caledonian mélange in Ireland: implications for tectonic models. Journal of the Geological Society, London 151, 307–14.CrossRefGoogle Scholar
Williams, D. M., Harkin, J. & Higgs, K. T. 1996. Implications of new microfloral evidence from the Clew Bay Complex for Silurian relationships in the western Irish Caledonides. Journal of the Geological Society, London 153, 771–7.CrossRefGoogle Scholar
Williams, D. M., Harkin, J. & Rice, A. H. N. 1997. Umbers, ocean crust and the Irish Caledonides: terrane transpression and the morphology of the Laurentian margin. Journal of the Geological Society, London 154, 829–38.CrossRefGoogle Scholar
Williams, D. M. & Harper, D. A. T. 1991. End-Silurian modifications of Ordovician terranes in western Ireland. Journal of the Geological Society, London 148, 165–71.CrossRefGoogle Scholar
Williams, D. M. & Rice, A. H. N. 1989. Low-angled extensional faulting and the emplacement of the Connemara Dalradian, Ireland. Tectonics 8, 417–28.CrossRefGoogle Scholar
Supplementary material: PDF

Rice Supplementary Material

Supplementary Material.pdf

Download Rice Supplementary Material(PDF)
PDF 439.4 KB