Skip to main content
    • Aa
    • Aa

40Ar–39Ar isotope constraints on the age of deformation in Charnwood Forest, UK

  • J. N. CARNEY (a1), P. ALEXANDRE (a2), M. S. PRINGLE (a3), T. C. PHARAOH (a1), R. J. MERRIMAN (a1) and S. J. KEMP (a1)...

40Ar–39Ar dating by a combination of spot analysis and step-heating has been carried out on mica fabrics from slaty cleavage and a shear zone in the Neoproterozoic to Cambrian rocks of Charnwood Forest, Leicestershire. The results indicate that crust adjacent to the eastern margin of the Midlands Microcraton was affected by localized epizonal metamorphism and penetrative deformation between 425 and 416 Ma (Silurian to earliest Devonian), somewhat earlier than the Acadian Phase of the Caledonian orogeny recorded elsewhere in southern Britain. The Charnwood cleavage geometry suggests that the deformation arose within a dextral transpressional regime along the eastern margin of the Midlands Microcraton. This tectonism may have overlapped with pre-Acadian sinistral transtensional movements documented for the Welsh Basin and Lake District areas, to the west and north of the Midlands Microcraton.

Corresponding author
Author for correspondence:
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

P. Alexandre , F. Chalot-Prat , A. Saintot , J. Wijbrans , R. Stephenson , M. Wilson , A. Kitchka & S. Stovba 2004. 40Ar/39Ar dating of magmatic activities in the Donbas Foldbelt and the Scythial Platforn (Eastern European Craton). Tectonics 23 (5), TC5002, 15 pp.

J. N. Carney 1999. Revisiting the Charnian Supergroup: new advances in understanding old rocks. Geology Today 15 (6), 221–9.

W. Compston , A. E. Wright & P. Toghill 2002. Dating the Late Precambrian volcanicity of England and Wales. Journal of the Geological Society, London 159, 323–39.

J. F. Dewey & R. A. Strachan 2003. Changing Silurian–Devonian relative plate motion in the Caledonides: sinistral transpression to sinistral transtension. Journal of the Geological Society, London 160, 219–29.

M. H. Dodson & D. Robinson 2006. A mid-Ordovician Rb–Sr isochron age from the Ingleton Group, North Yorkshire: metamorphism or diagenesis? Proceedings of the Yorkshire Geological Society 56 (2), 81–5.

H. Dong , C. M. Hall , A. N. Halliday , D. R. Peacor , R. J. Merriman & B. Roberts 1997. 40Ar/39Ar dating of Late Caledonian (Acadian) metamorphism and cooling of K-bentonites and slates from the Welsh Basin, U.K. Earth and Planetary Science Letters 150, 337–51.

B. Kaufmann , E. Trapp , K. Mezger & K. Weddige 2005. Two new Emsian (Early Devonian) U–Pb zircon ages from volcanic rocks of the Rhenish Massif (Germany): implications for the Devonian time scale. Journal of the Geological Society, London 162, 363–71.

H. J. Kisch 1990. Calibration of the anchizone: a critical comparison of illite ‘crystallinity’ scales used for definition. Journal of Metamorphic Geology 8, 3146.

R. J. Knipe 1981. The interaction of deformation and metamorphism in slates. Tectonophysics 78, 249–72.

M. K. Lee , T. C. Pharaoh & N. J. Soper 1990. Structural trends in central Britain from images of gravity and aeromagnetic fields. Journal of the Geological Society, London 147, 241–58.

G. Li , D. R. Peacor , R. J. Merriman & B. Roberts 1994. The diagenetic to low-grade metamorphic evolution of matrix white micas in the system muscovite–paragonite in a mudrock from Central Wales, U.K. Clays and Clay Minerals 42, 369–81.

I. McDougall & Z. Roksandic 1974. Total fusion 40Ar/39Ar ages using the HIFAR reactor. Journal of the Geological Society of Australia 21, 81–9.

D. McIlroy , M. D. Brasier & J. M. Moseley 1998. The Proterozoic–Cambrian transition within the ‘Charnian Supergroup’ of central England and the antiquity of the Ediacaran fauna. Journal of the Geological Society, London 155, 401–12.

W. S. McKerrow , C. Mac Niocaill & J. F. Dewey 2000. The Caledonian Orogeny redefined. Journal of the Geological Society, London 157, 1149–55.

M. Y. Meneisy & J. A. Miller 1963. A geochronological study of the crystalline rocks of Charnwood Forest, England. Geological Magazine 100, 507–23.

R. J. Merriman , T. C. Pharaoh , N. H. Woodcock & P. Daly 1993. The metamorphic history of the concealed Caledonides of eastern England and their foreland. Geological Magazine 130, 613–20.

R. J. Merriman , D. C. Rex , N. J. Soper & D. R. Peacor 1995 b. The age of Acadian cleavage in northern England, UK: K–Ar and TEM analysis of a Silurian metabentonite. Proceedings of the Yorkshire Geological Society 50, 255–65.

R. J. Merriman , B. Roberts & D. R. Peacor 1990. A transmission electron microscope study of white mica crystallite size distribution in a mudstone to slate transitional sequence, North Wales, U.K. Contributions to Mineralogy and Petrology 106, 2740.

R. J. Merriman , B. Roberts , D. R. Peacor & S. R. Hirons 1995 a. Strain-related differences in the crystal growth of white mica and chlorite: a TEM and XRD study of the development of metapelitic microfabrics in the Southern Uplands thrust terrane, Scotland. Journal of Metamorphic Geology 13, 559–76.

W. T. Parry , M. P. Bunds , R. L. Bruhn , C. M. Hall & J. M. Murphy 2001. Mineralogy, 40Ar/39Ar dating and apatite fission track dating of rocks along the Castle Mountain faults, Alaska. Tectonophysics 337, 149–72.

T. C. Pharaoh 1999. Palaeozoic terranes and their lithospheric boundaries within the Trans-European Suture Zone (TESZ): a review. Tectonophysics 314, 1741.

T. C. Pharaoh , R. J. Merriman , P. C. Webb & R. D. Beckinsale 1987. The concealed Caledonides of eastern England: preliminary results of a multidisciplinary study. Proceedings of the Yorkshire Geological Society 46, 355–69.

P. R. Renne , C. C. Swisher , A. L. Deino , D. B. Karner , T. L. Owens & D. J. Depaolo 1998. Intercalibration of standards, absolute ages and uncertanties in 40Ar/39Ar dating. Chemical Geology 145, 117–52.

S. C. Sherlock , S. P. Kelley , J. Zalasiewicz , D. Schofield , J. Evans , R. J. Merriman & S. J. Kemp 2003. Precise dating of low-temperature deformation: Strain-fringe analysis by 40Ar–39Ar laser microprobe. Geology 31, 219–22.

M. Sintubin , F. Brodkom & D. Laduron 1998. Cleavage-fold relationships in the Lower Cambrian Tubize Group, southeast Anglo-Brabant Fold Belt (Lembeek, Belgium). Geological Magazine 135, 217–26.

N. J. Soper , B. C. Webb & N. H. Woodcock 1987. Late Caledonian (Acadian) transpression in north-west England: timing, geometry and geotectonic significance. Proceedings of the Yorkshire Geological Society 46, 175–92.

J. S. Turner 1949. The deeper structure of central and northern England. Proceedings of the Yorkshire Geological Society 27, 280–97.

B. A. Van de Pluijm , N.-C. Ho , D. R. Peacor & R. J. Merriman 1998. Contradictions of slate formation resolved. Nature 392, 348.

G. Van Grootel , J. Verniers , B. Geerkens , D. Laduron , M. Verhaeren , J. Hertogen & W. De Voss 1997. Timing of magmatism, foreland basin development, metamorphism and inversion in the Anglo-Brabant fold belt. Geological Magazine 134, 607–16.

I. M. Villa 1998. Isotopic closure. Terra Nova 10, 42–7.

L. N. Warr & A. H. N. Rice 1994. Interlaboratory standardization and calibration of clay mineral crystallinity and crystallite size data. Journal of Metamorphic Geology 12, 141–52.

N. H. Woodcock 1990. Transpressive Acadian deformation across the Central Wales Lineament. Journal of Structural Geology 12, 329–37.

N. H. Woodcock & T. C. Pharaoh 1993. Silurian facies beneath East Anglia. Geological Magazine 130, 681–90.

N. H. Woodcock , N. J. Soper & R. A. Strachan 2007. A Rheic cause for Acadian deformation in Europe. Journal of the Geological Society, London 164, 1023–36.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Geological Magazine
  • ISSN: 0016-7568
  • EISSN: 1469-5081
  • URL: /core/journals/geological-magazine
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 3
Total number of PDF views: 5 *
Loading metrics...

Abstract views

Total abstract views: 47 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 27th June 2017. This data will be updated every 24 hours.