ABSTRACT

Examples of structures ascribed to penecontemporaneous deformation in the Lower Carboniferous of south Pembrokeshire, Wales (United Kingdom), are recorded. The structures occur in units within a neritic calcareous sequence and appear to be developed at a similar stratigraphic level at several localities.

Evidence derived from a critical study of the geometry of the deformed bodies and their mutual relationships, in many cases, cannot be completely reconciled with theories of origin involving only foundering or with those which require only sub-horizontal shear deformation and translation. It is suggested that many structures may have originated through a combination of these two modes of deformation. Further support for this hypothesis arises from the strong preferred orientation of the structures observed in many of the deformed units. However, when assessed in the light of regional paleogeography and with the evidence of the directional criteria in associated beds, the orientation of the deformed bodies appears to be more intimately, controlled by local rather than regional factors. /P>