Ordovician provincial signals from Appalachian- Caledonian terranes



Statistical analysis of mainly mid to deep-shelf Ordovician brachiopod faunas from localities within and marginal to the Appalachian- Caledonian Orogen reveals biogeographical patterns not entirely consistent with those presumed for the progressive orthogonal closure of the Iapetus Ocean. Correspondence analysis of faunas of late Arenig-early Llanvirn, late Llandeilo-earliest Caradoc and late Ashgill age emphasize the importance of marginal and island faunas, the role of regressions and transgressions on faunal distributions and the effects of climatic change in the definition of biogeographical trends during the Ordovician.