Strike-slip faulting along the Church Stretton Lineament, Old Radnor Inlier, Wales

The Old Radnor Inlier comprises Precambrian sediments unconformably overlain by Wenlock age limestones and shales. Its structure is dominated by steep strike-slip faults. Major NE-SW faults probably bound the inlier and are linked by more northerly faults to form a strike-slip duplex. Strike-slip faults within the inlier match a Riedel shear system, with observed dextral offsets on a NW striking set and implied sinistral offsets on the major inlier-parallel faults. Subordinate dip-slip faults are anomalously oriented, but may be Riedel shears reactivated during progressive sinistral transtension across the inlier. Pre-Wenlock deformation is recorded by the tilting of the Precambrian sediments and by some faults that do not cut the unconformity. On regional grounds, this deformation might be Ashgill (late Ordovician) or late Precambrian-early Cambrian in age. The strike-slip component now predominating was imposed in post-Wenlock time, probably during the regional sinistral transpression of the Acadian (Late Caledonian) event in Early Devonian time. Later Variscan and Mesozoic components cannot be ruled out.

[1]  N. Woodcock,et al.  Is the Welsh Borderland Fault System a terrane boundary? , 1988, Journal of the Geological Society.

[2]  R. Smith,et al.  Acadian tectonics of Wales during Avalonia/Laurentia Convergence , 1988 .

[3]  N. Woodcock,et al.  Late Caledonian (Acadian) transpression in north-west England: timing, geometry and geotectonic significance , 1987 .

[4]  D. Hutton.  Strike-slip terranes and a model for the evolution of the British and Irish Caledonides , 1987, Geological Magazine.

[5]  R. Sibson.  Stopping of earthquake ruptures at dilational fault jogs , 1985, Nature.

[6]  N. J. Soper,et al.  Late Caledonian sinistral displacements in Britain: Implications for a three‐plate collision model , 1984 .

[7]  N. Woodcock.  The Pontesford Lineament, Welsh Borderland , 1984, Journal of the Geological Society.

[8]  J. H. James.  The structure and stratigraphy of part of the Pre-Cambrian outcrop between Church Stretton and Linley, Shropshire , 1956, Quarterly Journal of the Geological Society of London.

[9]  O. T. Jones.  The Geological Evolution of Wales and the Adjacent Regions , 1955, Quarterly Journal of the Geological Society of London.

[10]  N. Holgate,et al.  The Igneous Rocks of the Stanner-Hanter District, Radnorshire , 1941, Geological Magazine.

[11]  R. E. Janssen.  Shrewsbury District Including the Hanwood Coalfield. R. W. Pocock , T. H. Whitehead , C. B. Wedd , T. Robertson , 1939 .

[12]  E. J. Garwood,et al.  On the Geology of the Old Radnor District, with special reference to an Algal Development in the Woolhope Limestone , 1918, Quarterly Journal of the Geological Society of London.

[13]  C. Callaway.  On Longmyndian Inliers at Old Radnor and Huntley, Gloucestershire , 1900, Quarterly Journal of the Geological Society of London.

[14]  Ramsay,et al.  Sketch of the Structure of parts of North and South Wales , 1848, Quarterly Journal of the Geological Society of London.

[15]  W. Mckerrow.  Wenlock to Givetian deformation in the British Isles and the Canadian Appalachians , 1988, Geological Society, London, Special Publications.

[16]  H. W. Roehler.  Structure and stratigraphy , 1987 .

[17]  N. Woodcock.  Kinematics of strike-slip faulting, builth Inlier, mid-Wales , 1987 .

[18]  N. Woodcock,et al.  Strike-slip duplexes , 1986 .

[19]  N. Woodcock,et al.  Early Palaeozoic sedimentation and tectonics in Wales , 1984 .

[20]  T. Owen,et al.  THE STRUCTURE OF THE MAIN SOUTH WALES COALFIELD AND ITS MARGINS , 1983 .

[21]  R. E. Wilcox,et al.  Basic Wrench Tectonics , 1973 .

[22]  T. Owen.  Geology Explained in South Wales , 1973 .

[23]  B. Hains.  The geology of the Craven Arms area , 1969 .

[24]  W. F. Whittard.  A geology of south Shropshire , 1952 .

[25]  R. W. Pocock,et al.  The Welsh borderland , 1935 .

[26]  W. W. Watts.  The geology of South Shropshire , 1925 .