TURBIDITES FROM THE CLEW BAY COMPLEX, IRELAND - PROVENANCE BASED ON PETROGRAPHY, GEOCHEMISTRY AND CRUSTAL RESIDENCE VALUES

The Clew Bay Complex in the Irish Caledonides represents a Caledonian element separating the Irish-Scottish Dalradian to the north from the South Mayo Ordovician are basins to the south. The petrographic, geoch emical and crustal residence characteristics of the Silurian sandstone s within the complex are presented. Petrological analysis indicates th at the sandstones were derived from a transitional continental provena nce, possibly a passive continental margin or the cratonic flank of a foreland basin. Whole rock geochemistry confirms this provenance type and demonstrates the absence of any significant ophiolite detritus. Sm -Nd model ages indicate a possible derivation from Upper Dalradian or Torridonian rocks, although a mixed provenance may also be considered. These data indicate distinct differences between these turbidites and those of the nearby North Galway succession and suggest that the Clew Bay Complex could be regarded as a suspect terrane with respect to at least parts of the South Mayo are zone. (C) 1996 by John Wiley & Sons , Ltd.