R. B. Evans

British Geological Survey

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R.M. Carruthers

Queensland Department of Natural Resources, Mines and Energy

Andrew J. McDonald

Cornell University

V. V. C. Ranasinghe

C. J. N. Fletchert

Natural Environment Research Council

Brian E. Leveridge

British Geological Survey

T. Hatherton

Geophysical Survey

D. B. Pattiaratchi

C. J. N. Fletcher

Geological Society of London

A. J. Reedman

British Geological Survey

David Gordon Wilson

Sandia National Laboratories

Cooperative Institutions

British Geological Survey

Institute of Geological Sciences

Natural Environment Research Council

Geological Society of London

Instytut Nauk Geologicznych

Aberystwyth University

University of British Columbia

United States Geological Survey

Queensland Department of Natural Resources, Mines and Energy

Institute of Geology of Ore Deposits Petrography Mineralogy and Geochemistry

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Some constraints on the form of the Welsh Basin from regional gravity and aeromagnetic data, with particular reference to Central Wales

Geological Magazine (1992)

R.M. Carruthers C. J. N. Fletcher Andrew J. McDonald R. B. Evans

Abstract Gravity and aeromagnetic data sets provide systematic coverage over the whole of the Welsh Basin. Physical property information shows considerable overlap in densities within the Lower Palaeozoic and Precambrian formations, with relatively few units of the exposed succession being strongly magnetic. While the geophysical anomalies cannot be interpreted unambiguously in terms of these sources, the data can still be used to test different geological models and to indicate the range of possible solutions. The major fault zones are seen to influence the anomaly patterns in a variety of ways, reflecting a combination of differing near-surface contrasts and effects within the underlying basement. The general increase in gravity values towards Cardigan Bay may originate from the lower crust, and the large amplitude aeromagnetic low seen over Cardigan Bay indicates that a distinctive change in the character of the crust occurs here. Two-dimensional modelling in central Wales shows that a westward thickening of the Welsh Basin, to a maximum of about 10 km, may also be significant. It is necessary to postulate a separation of the base of denser, Lower Palaeozoic rocks from the underlying, more magnetic basement in order to account for offsets in anomaly source locations. This implies the presence of less dense Cambrian sediments and/or non-magnetic components of the Precambrian basement.

Basement

Anomaly (physics)

Welsh

10.1017/s0016756800021671

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The Arfon Group (‘Arvonian’) of North Wales

Proceedings of the Geologists Association (1984)

A. J. Reedman Brian E. Leveridge R. B. Evans

Outcrop

Sequence (biology)

Alluvial fan

10.1016/s0016-7878(84)80062-0

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Citations (41)

Gravity map of Sri Lanka, 1:1 000 000

T. Hatherton D. B. Pattiaratchi V. V. C. Ranasinghe R. B. Evans

Sri lanka

Source

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Interpretation of the regional gravity and magnetic surveys of Wales, using shaded relief and Euler deconvolution techniques

Geological Magazine (1992)

Andrew J. McDonald C. J. N. Fletchert R.M. Carruthers David Gordon Wilson R. B. Evans

Abstract Regional gravity and aeromagnetic data of Wales have been processed using a variety of techniques. Image processing has greatly assisted qualitative interpretation, whilst automated procedures have provided additional quantitative information. The shaded relief images emphasize gradients in the potential fields, and are useful for displaying strong linear features. The Euler deconvolution method produces plotted solution maps, which define the position of the source of the gravity and magnetic anomalies. Euler solution maps of Wales and the adjacent continental shelf are presented for the first time. These maps are interpreted in relation to the known geology, with special emphasis on the Lower Palaeozoic Welsh Basin. It is proposed that the Euler solutions define a network of fault-bounded blocks within the Precambrian basement.

Basement

10.1017/s0016756800021683

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Citations (18)