THE IRISH VARISCIDES - PROBLEMS, PERSPECTIVES AND SOME SOLUTIONS

A review is presented of interpretations made to date of the Irish Var iscides, and the various models of Late Palaeozoic crustal evolution. An examination is then made of the factors controlling Variscan strain in Ireland, including lithological competence, basement fabric and ba sement-cover thickness. From this, the difficulties of recognizing Var iscan 'fronts' and 'fold belts' are emphasized. In order to determine whether all putative Variscan strain is indeed Variscan in age, new ti me-temperature data (vitrinite reflectance; apatite fission track popu lations) are discussed, along with offshore data. A case is then prese nted for recognizing quite distinct episodes of both Variscan and post -Variscan heating and deformation. Some of the implications for the Va riscides to the east are briefly examined, and the suitability of a re gional 'escape tectonics' model is tested.