Lineaments and basement domains: an alternative view of Dalradian evolution

This paper examines the evidence for basement structures of predominantly non-Caledonoid trend which appear to have influenced the development of the Dalradian belt in Scotland. A number of domains or blocks separated by dominantly trans-Caledonoid lineaments are recognized on the basis of geophysical, stratigraphical and geochemical patterns. These are thought to reflect fault-bounded depositional basins controlled by basement lineaments during the extensional phases of the Caledonian 9orogeny9. In addition the recognition of a number of these domains and lineaments in the structural, metamorphic and igneous data-sets for the Dalradian belt, shows the continuing influence of these basement controlled features throughout the compressional and uplift phases of the orogenesis. A possible tectonic model is proposed which envisages the depositional basins forming in a setting dominated by Caledonoid trending transcurrent faults and a major pull-apart basin forming on a trans-Caledonoid axis.