Hostname: page-component-77c89778f8-swr86 Total loading time: 0 Render date: 2024-07-17T15:06:08.707Z Has data issue: false hasContentIssue false
  • English
  • Français

Evidence on the deep structure of the Anglo-Brabant Massif from gravity and magnetic data

Published online by Cambridge University Press:  01 May 2009

M. K. Lee ,
T. C. Pharaoh ,
J. P. Williamson ,
C. A. Green  and
W. De Vos
M. K. Lee
Affiliation:
British Geological Survey, Keyworth, Nottingham, U.K.
T. C. Pharaoh
Affiliation:
British Geological Survey, Keyworth, Nottingham, U.K.
J. P. Williamson
Affiliation:
British Geological Survey, Keyworth, Nottingham, U.K.
C. A. Green
Affiliation:
British Geological Survey, Keyworth, Nottingham, U.K.
W. De Vos
Affiliation:
Belgische Geologische Dienst, Brussels, Belgium
Get access Rights & Permissions [Opens in a new window]

Abstract

Gravity and aeromagnetic data from Britain, Belgium and the southern North Sea have been compiled to provide coverage of the greater part of the Anglo-Brabant Massif. Colour pseudo-relief maps of the gravity and magnetic fields highlight important anomalies and trends which provide new information on the structure of the massif and its margins. Within the massif, prominent SSE-trending geophysical lineaments define the margins of distinctive blocks within the upper crust. These are cross-cut on the northeastern margin of the massif by prominent ESE- and SE-trending magnetic and gravity lineaments. The possible history and origin of the more prominent geophysical anomalies and lineaments are considered. Integrated modelling of the potential field data has been carried out along the BIRPS MOBIL-7 seismic reflection line to provide an interpretation of crustal structure across the northeast margin of the massif constrained by all three datasets. The principal features of the model are a non-reflective, non-magnetic upper crust, interpreted as the Caledonian fold–thrust belt, overlying a heterogeneous middle–lower crust with laterally varying reflectivity, magnetization and density. ESE-trending magnetic anomalies along the northeast edge of the massif are explained in terms of an irregular mid-crustal magnetic layer with a susceptibility comparable to that of the Tubize Group in the Brabant Massif. The top of this body is coincident with prominent dipping mid-crustal reflectors observed on the seismic reflection profile and its overall geometry is compatible with mid-crustal imbrication inferred from the seismic data.

Type
Articles
Information
Geological Magazine , Volume 130 , Issue 5 , September 1993 , pp. 575 - 582
Copyright
Copyright © Cambridge University Press 1993

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

Allsop, J. M. 1987. Patterns of late Caledonian intrusive activity in eastern and northern England from geophysics, radiometric dating and basement geology. Proceedings of the Yorkshire Geological Society 46, 335–53.CrossRefGoogle Scholar
Blundell, D. J. 1993. Deep structure of the Anglo-Brabant Massif revealed by seismic profiling. Geological Magazine 130, 563–7.CrossRefGoogle Scholar
Blundell, D. J., Hobbs, R. W., Klemperer, S. L., Scott-Robinson, R., Long, R. E., West, T. E. & Duin, E. 1991. Crustal structure of the central and southern North Sea from B1RPS deep seismic reflection profiling. Journal of the Geological Society, London 148, 445–58.CrossRefGoogle Scholar
Bott, M. H. P., Robinson, J. & Kohnstamm, M. A. 1978. Granite beneath Market Weighton, East Yorkshire. Journal of the Geological Society, London 135, 535–43.CrossRefGoogle Scholar
Busby, J. P., Kimbell, G. S. & Pharaoh, T. C. 1993. Integrated geophysical/geological modelling in southern Britain. Geological Magazine 130, 593–604.CrossRefGoogle Scholar
Cameron, T. D. J., Crosby, A., Balson, P. S., Jeffery, D. H., Lott, G. K., Bulat, J. & Harrison, D. J. 1992. The Geology of the Southern North Sea. British Geological Survey, United Kingdom Offshore Regional Report. London: HMSO.Google Scholar
Chacksfield, B. C., De Vos, W., D'Hooge, L., Dusar, M., Lee, M. K., Poitevin, C., Royles, C. & Verniers, J. 1993. A new look at Belgian aeromagnetic and gravity data through image-based display and integrated modelling techniques. Geological Magazine 130, 583–591.CrossRefGoogle Scholar
Day, G. A., Anderson, O. B., Ensager, K., Finnistrom, E. G., Hospers, J., Liebe, T., Makris, J., Plaumann, S., Strang Van Hees, G. & Walter, S. A. 1991. Bouguer gravity anomaly map of the North Sea, 1:100000. Keyworth: British Geological Survey.Google Scholar
Donato, J. A. 1993. A buried granite batholith and the origin of the Sole Pit Basin, UK southern North Sea. Journal of the Geological Society, London 150, 255–8.CrossRefGoogle Scholar
Donato, J. A. & Megson, J. B. 1990. A buried granite batholith beneath the East Midlands Shelf of the Southern North Sea Basin. Journal of the Geological Society, London 147, 133–40.CrossRefGoogle Scholar
Dynamic Graphics. 1986. Interactive Surface Modelling User's Guide. Berkeley, California: Dynamic Graphics Inc.Google Scholar
Green, C. A. 1989. Colmap: a colour mapping package for 2-D geophysical data. British Geological Survey Technical Report WK/89/19.Google Scholar
Kearey, P. 1991. A possible basaltic deep source of the south-central England magnetic anomaly. Journal of the Geological Society, London 148, 775–80.CrossRefGoogle Scholar
Klemperer, S. L. (& BIRPS). 1987. Reflectivity of the crystalline crust: hypotheses and tests. Geophysical Journal of the Royal Astronomical Society 89, 217–22.CrossRefGoogle Scholar
Lee, M. K., Pharaoh, T. C. & Green, C. A. 1991. Structural trends in the concealed basement of eastern England from images of regional potential field data. Annales de la Société Géologique de Belgique 114, 45–62.Google Scholar
Lee, M. K., Pharaoh, T. C. & Soper, N. J. 1990. Structural trends in central Britain from images of gravity and aeromagnetic fields. Journal of the Geological Society, London 147, 241–58.CrossRefGoogle Scholar
Matthews, D. H. 1986. Seismic reflections from the lower crust around Britain. In The Nature of the Lower Continental Crust (eds Dawson, J. B., Carswell, D. A., Hall, J. and Wedepohl, K. H.), pp. 11–21. Special Publication of the Geological Society no. 24.Google Scholar
Pedley, R. C. 1991. Gravmag user manual: interactive 2.5D gravity and magnetic modelling program. Keyworth: British Geological Survey.Google Scholar
Pharaoh, T. C., Brewer, T. S. & Webb, P. C. 1993. Subduction-related magmatism of late Ordovician age in eastern England. Geological Magazine 130, 647–56.CrossRefGoogle Scholar
Pharaoh, T. C., Merriman, R. J., Webb, P. C. & Beckin-Sale, R. D. 1987. The concealed Caledonides of eastern England: preliminary results of a multidisciplinary study. Proceedings of the Yorkshire Geological Society 46, 355–69.CrossRefGoogle Scholar
Reston, T. J. & Blundell, D. J. 1987. Possible mid-crustal shears at the edge of the London Platform. Geophysical Journal of the Royal Astronomical Society 89, 251–8.CrossRefGoogle Scholar
Rijkers, R. H. B., Duin, E. J. T., Dusar, M. & Langen-Aeker, V. 1993. Crustal structure of the London-Brabant Massif, southern North Sea. Geological Magazine 130, 569–74.CrossRefGoogle Scholar
Smith, I. F. & Royles, C. P. 1989. The digital aeromagnetic survey of the United Kingdom. British Geological Survey Technical Report WK/89/5.Google Scholar
Soper, N. J., Webb, B. C. & Woodcock, N. J. 1987. Late Caledonian (Acadian) transpression in North West England: timings, geometry and geotectonic significance. Proceedings of the Yorkshire Geological Society 46, 175–92.CrossRefGoogle Scholar
Van Hoorn, B. 1987. Structural evolution, timing and tectonic style of the Sole Pit Inversion. Tectonophysics 137, 239–84.CrossRefGoogle Scholar
Wilson, A. A. & Cornwell, J. D. 1982. Institute of Geological Sciences borehole at Beckermonds Scar, North Yorkshire. Proceedings of the Yorkshire Geological Society 44, 59–82.CrossRefGoogle Scholar
Woodcock, N. H. & Pharaoh, T. C. 1993. Silurian fades beneath East Anglia. Geological Magazine 130, 681–90.CrossRefGoogle Scholar