Hostname: page-component-848d4c4894-sjtt6 Total loading time: 0 Render date: 2024-06-27T00:35:25.809Z Has data issue: false hasContentIssue false
  • English
  • Français

Palaeozoic palaeomagnetic studies, in the Welsh Basin-recent advances

Published online by Cambridge University Press:  01 May 2009

J. E. T. Channell ,
C. McCabe ,
T. H. Torsvik ,
A. Trench  and
N. H. Woodcock
J. E. T. Channell
Affiliation:
Department of Geology, University of Florida, Gainesville, FL 32611, USA
C. McCabe
Affiliation:
Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, USA
T. H. Torsvik
Affiliation:
Geological Survey of Norway, P. B. 3006 Lade, N-7002 Trondheim, Norway
A. Trench
Affiliation:
Department of Geology, University of Western Australia, Nedlands, Perth, WA 6009, Australia
N. H. Woodcock
Affiliation:
Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, U.K.
Get access Rights & Permissions [Opens in a new window]

Abstract

In the last two years, new palaeomagnetic data from Wales have resulted in radical revision of the Ordovician palaeogeography of Eastern Avalonia, part of the southern margin of the Iapetus Ocean. Combined with Palaeozoic palaeomagnetic data from Laurentia and Gondwana, these data suggest that Eastern Avalonia was a peri-Gondwanide high latitude continental fragment during at least part of Ordovician time, with a palaeolatitude of about 62° S and 51° S in Arenig and Llanvirn time, respectively. This implies a latitudinal width of the early Ordovician Iapetus Ocean between Eastern Avalonia and Laurentia of at least 30°. Geological evidence for the proximity of Eastern Avalonia and Laurentia suggests that the intervening Iapetus Ocean closed during Silurian time, from late Llandovery to early Ludlow. Recent palaeolatitude data from the Iapetus bordering continents are consistent with closure by middle to late Silurian time. New pre-Acadian early Devonian palaeomagnetic data from the Old Red Sandstone places the Welsh Basin at about 17° S, consistent with a palaeogeography in which Laurentia, Baltica, Avalonia, Armorica, and possibly Gondwana, were part of a single supercontinent. Pervasive late Carboniferous/early Permian remagnetization affects the Welsh Basin. The remagnetization is probably associated with fluids emanating from the Variscan thrust front. We do not observe remagnetization associated with Acadian orogeny and the remagnetizations, which have been studied in more detail in North America, appear to be a unique feature of the Variscan-Hercynian-Alleghenian orogeny.

Type
Articles
Information
Geological Magazine , Volume 129 , Issue 5 , September 1992 , pp. 533 - 542
Copyright
Copyright © Cambridge University Press 1992

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

Briden, J. C. & Morris, W. A. 1973. Palaeomagnetic studies in the British Caledonides-III Igneous rocks of the northern Lake District, England. Geophysical Journal of the Royal Astronomical Society 34, 27–46.CrossRefGoogle Scholar
Briden, J. C., Turnell, H. B. & Watts, D. R. 1984. British paleomagnetism, Iapetus Ocean, and the Great Glen Fault. Geology 12, 428–31.2.0.CO;2>CrossRefGoogle Scholar
Briden, J. C. & Mullan, A. J. 1984. Superimposed recent, Permo-Carboniferous and Ordovician palaeomagnetic remanence in the Builth Volcanic Series, Wales. Earth and Planetary Science Letters 69, 413–21.CrossRefGoogle Scholar
Bullard, E. C., Eve, J. E. & Smith, A. G. 1965. A symposium on continental drift, IV, The fit of the continents around the Atlantic. Philosophical Transactions of the Royal Society of London 258, 41–51.Google Scholar
Chamalaun, F. H. & Creek, K. M. 1964. Thermal demagnetisation studies on the Old Red Sandstone of the Anglo-Welsh cuvette. Journal of Geophysical Research 69, 1607–16.CrossRefGoogle Scholar
ChannellJ. E., T. J. E., T., McCabe, C. & Woodcock, N. H. 1992. An Early Devonian (pre-Acadian) magnetization component recorded in the Lower Old Red Sandstone of South Wales (UK). Geophysical Journal International 108, 883–94.CrossRefGoogle Scholar
Channell, J. E. T. & McCabe, C. 1992. Paleomagnetic data from the Borrowdale Volcanic Group (English Lake District): volcano-tectonics and Late Ordovician paleolatitudes. Journal of the Geological Society, London. in press.CrossRefGoogle Scholar
Claesson, K. C. 1978. Swedish Ordovician limestones: problems in clarifying their directions of magnetization. Physics of Earth and Planetary Interiors 16, 65–72.CrossRefGoogle Scholar
Creer, K. M. 1968. Palaeozoic palaeomagnetism. Nature 219, 246–50.CrossRefGoogle Scholar
Deutsch, E. R. 1980. Magnetism of the Mid-Ordovician Tramore volcanics, SE Ireland, and the question of a wide Proto-Atlantic Ocean. Journal of Geomagnetism and Geoelectricity 32, III, 77–98.CrossRefGoogle Scholar
Douglass, D. N. 1988. Paleomagnetics of Ringerike Old Red Sandstone and related rocks, southern Norway: implications for pre-Carboniferous separation of Baltica and British terranes. Tectonophysics 148, 11–27.CrossRefGoogle Scholar
House, M. R., Richardson, J. B., Chaloner, W. G., Allen, J. R. L., Holland, C. H. & Westoll, T. S. 1977. The correlation of Devonian rocks of the British Isles. Geological Society, London. Special Report, no. 7.Google Scholar
Jones, O. T. & Pugh, W. J. 1949. An early Ordovician shoreline in Radnorshire, near Builth Wells. Quarterly Journal of the Geological Society of London 105, 65–99.CrossRefGoogle Scholar
Kent, D. V. & Van Der Voo, R. 1990. Palaeozoic palaeogeography from palaeomagnetism of the Atlantic bordering continents. In Palaeozoic Palaeogeography and Biogeography (eds McKerrow, W. S. and Scotese, C. R.), pp. 49–56. Geological Society of London.Google Scholar
Kokelaar, B. P., Howells, M. F., Bevins, R. E., Roach, R. A. & Dinkley, P. N. 1984. The Ordovician marginal basin of Wales. In Marginal Basin Geology (eds Kokelaar, B. P. and Howells, M. F.), pp. 245–69. Oxford: Blackwell.Google Scholar
Lynas, B. D. T. 1988. Evidence for dextral oblique-slip faulting in the Shelve Ordovician inlier, Welsh borderland: implications for the south British Caledonides. Geological Journal 23, 39–57.CrossRefGoogle Scholar
McCabe, C. & Elmore, R. D. 1989. The occurrence and origin of Late Palaeozoic remagnetization in the sedimentary rocks of North America. Reviews of Geophysics 27, 471–94.CrossRefGoogle Scholar
McCabe, C. & Channell, J. E. T. 1990. Paleomagnetic results from volcanic rocks of the Shelve Inlier, Wales: evidence for a wide Late Ordovician Iapetus Ocean in Britain. Earth and Planetary Science Letters 96, 458–68.CrossRefGoogle Scholar
McCabe, C. & Channell, J. E. T. 1991. Reply to comment of A. Trench and T. H., Torsvik on “Paleomagnetic results from volcanic rocks of the Shelve Inlier, Wales: evidence for a wide Late Ordovician Iapetus Ocean in Britain”. Earth and Planetary Science Letters 104, 540–4.CrossRefGoogle Scholar
McCabe, C., Channell, J. E. T. & Woodcock, N. H. 1992. Further paleomagnetic results from the Builth Well Ordovician Inlier, Wales. Journal of Geophysical Research. (in press).CrossRefGoogle Scholar
McClelland-Brown, E. 1983. Palaeomagnetic studies of fold development and propagation in the Pembroke-shire Old Red Sandstone. Tectonophysics 98, 131–46.CrossRefGoogle Scholar
McClelland, E. 1987. Palaeomagnetic result from the Devonian Llandstadwell Formation, Dyfed, Wales-Discussion. Tectonophysics 143, 335–6.CrossRefGoogle Scholar
Morris, W. A., Briden, J. C., Piper, J. D. A. & Sallomy, J. T. 1973. Palaeomagnetic studies in the British Caledonides–V, Miscellaneous new data. Geophysical Journal of the Royal Astronomical Society 34, 69–105.CrossRefGoogle Scholar
Piper, J. D. A. 1975. Palaeomagnetism of Silurian lavas of Somerset and Gloustershire, England. Earth and Planetary Science Letters 25, 355–60.CrossRefGoogle Scholar
Piper, J. D. A. 1978. Palaeomagnetic survey of the (Palaeozoic) Shelve Inlier and Berwyn Hills, Welsh Border-land. Geophysical Journal of the Royal Astronomical Society 53, 355–71.CrossRefGoogle Scholar
Piper, J. D. A. & Briden, J. C. 1973. Palaeomagnetic studies in the British Caledonides - I Igneous rocks of the Builth Wells - Llandrindnod Wells Ordovician Inlier, Radnorshire, Wales. Geophysical Journal of the Royal Astronomical Society 34, 1–12.CrossRefGoogle Scholar
Soper, N. J., Webb, B. C. & Woodcock, N. H. 1987. Late Caledonian transpression in north-west England: timing, geometry and geotectonic significance. Proceedings of the Yorkshire Geological Society 46, 175–92.CrossRefGoogle Scholar
Stearns, C. & Van Der Voo, R. 1987. Palaeomagnetic results from the Lower Devonian Llandstadwell Formation, Dyfed, Wales. Tectonophysics 143, 329–34.CrossRefGoogle Scholar
Thomas, C. & Briden, J. C. 1976. Anomalous geomagnetic field during the Late Ordovician. Nature 259, 380–2.CrossRefGoogle Scholar
Torsvik, T. H. & Trench, A. 1991. The Lower-Middle Ordovician palaeofield of Scandanavia, southern Sweden “revisited”. Physics of Earth and Planetary Interiors 65, 283–91.CrossRefGoogle Scholar
Torsvik, T. H. & Trench, A. 1992. Palaeomagnetic results from the East Mendip Inlier, southern Britain (E. Avalonia): palaeogeographic implications. Annales Geophysicae 10, C24.Google Scholar
Trench, A. & Torsvik, T. H. 1991 a. A revised Palaeozoic apparent polar wander path for southern Britain (Eastern Avalonia). Geophysical Journal International 104, 227–33.CrossRefGoogle Scholar
Trench, A. & Torsvik, T. H. 1991 b. Comment on “Palaeomagnetic results from volcanic rocks of the Shelve Inlier, Wales: evidence for a wide Late Ordovician Iapetus Ocean in Britain” by C. McCabe and J. E. T. Channel!. Earth and Planetary Science Letters 104, 535–9.CrossRefGoogle Scholar
Trench, A. & Torsvik, T. H. 1992. The Lower Palaeozoic apparent polar wander path for Baltica: palaeomagnetic data from Silurian limestones of Gotland, Sweden. Geophysical Journal International, in press.Google Scholar
Trench, A., Torsvik, T. H., Smethurst, M. A., Wood-Cock, N. H. & Metcalf, R. 1991. A paleomagnetic study of the Builth Wells - Llandrindod Wells Ordovician Inlier, Wales: paleogeographic and structural implications. Geophysical Journal International 105, 477–89.CrossRefGoogle Scholar
Trench, A., Torsvik, T. H., Dentith, M. C., Walderhaug, H. & Traynor, J.-J. 1992. A high southerly palaeolatitude for Southern Britain in Early Ordovician times: palaeomagnetic data from the Treffgarne Volcanic formation SW Wales. Geophysical Journal International 108, 89–100.CrossRefGoogle Scholar
Van Der Voo, R. 1990. Phanerozoic paleomagnetic poles from Europe and North America and comparisons with continental reconstructions. Reviews of Geophysics 28, 167–206.CrossRefGoogle Scholar
Van Der Voo, R. 1992. Paleomagnetism of Atlantis, Tethys and Iapetus. Cambridge University Press, Cambridge, U. K. in press.Google Scholar
Van Der Voo, R. & Johnson, R. J. 1985. Paleomagnetism of the Dunn Point Formation (Nova Scotia): high paleolatitudes for the Avalon Terrane in the Late Ordovician. Geophysical Research Letters 12, 337–40.CrossRefGoogle Scholar
Woodcock, N. H. 1984. The Pontesford Lineament, Welsh Borderland. Journal of the Geological Society, London 141, 1001–14.CrossRefGoogle Scholar
Woodcock, N. H. 1987. Structural geology of the Llandovery Series in the type area, Dyfed, Wales. Geological Journal 22, 199–209.CrossRefGoogle Scholar
Woodcock, N. H. & Gibbons, W. 1988. Is the Welsh borderland fault system a terrane boundary? Journal of the Geological Society, London 145, 915–23.CrossRefGoogle Scholar
Woodcock, N. H., Awan, M. A., Johnson, T. E., MacKie, A. H. & Smith, R. D. A. 1988. Acadian tectonics of Wales during Avalonia/Laurentia convergence. Tectonics 7, 483–95.CrossRefGoogle Scholar
Zijderveld, J. D. A., 1967. The natural remanent magnetization of the Exeter volcanic traps (Permian, Europe). Tectonophysics 4, 121–53.CrossRefGoogle Scholar