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Structure and deformation history of the Central Wales Synclinorium, northeast Dyfed: Evidence for a long‐lived basement structure
Author(s) -
Smith R. D. A.
Publication year - 1987
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3350220516
Subject(s) - syncline , sinistral and dextral , geology , clockwise , fold (higher order function) , echelon formation , cleavage (geology) , seismology , shear (geology) , transpression , geometry , fault (geology) , paleontology , tectonics , mechanical engineering , mathematics , fracture (geology) , engineering
The Central Wales Synclinorium in northeast Dyfed is markedly asymmetrical, dominated by strongly southeast verging NE–SW trending F 1 folds with an axial planar to mildly clockwise‐transecting cleavage. Within the Pysgotwr Fault Belt, a narrow braided array of steep faults developed in the core of the structure, the F 1 folds and S 1 cleavage are locally refolded into en echelon ENE–WSW F 2 folds with an associated S 2 cleavage. F 2 and S 2 geometry and orientation strongly suggest development in response to an important element of oblique simple shear involving components of sinistral strikeslip and NW‐down dip‐slip. The Pysgotwr Fault Belt is anomalous in the context of fold‐dominated mid‐Wales and appears to be associated with a long‐lived basement structure which significantly influenced Welsh Basin topography in early Silurian time.