EARLY CARADOC TRILOBITES OF EASTERN IRELAND AND THEIR PALEOGEOGRAPHICSIGNIFICANCE

Twenty-five trilobite species belonging to twenty-three genera are rec orded from the Caradoc Knockerk Formation of the Grangegeeth area, eas tern Ireland. Arthrorhachis knockerkensis and Birmanites salteri are n ew, while Barrandia sp, and Flexicalymene sp. possibly represent new s pecies. The faunas occur predominantly in the lower parts of the Knock erk House Sandstones Member and younger Brickwork's Quarry Shales Memb er. The older fauna is of early Caradoc age and shows affinities with species from the Balclatchie and Lower Ardwell groups at Girvan. The y ounger trilobite fauna and associated graptolites are indicative of th e Climacograptus peltifer Biozone (possibly Harnagian). The Laurentian /Scoto-Appalachian affinities of the Grangegeeth Caradoc faunas indica te that the Grangegeeth terrane was closest to Laurentia during the ea rly Caradoc and that the final Iapetus Suture line must lie to the sou th of the Grangegeeth terrane.