Abstract

M. Parkes & A. Vaughan write: The recent paper on sequence stratigraphy of the Palaeozoic Welsh Basin (Woodcock 1990) illustrates how new developments can be applied to extensively studied areas. Our discussion, by contrast, concerns eastern Ireland where accumulated data are fewer, but where recent work has clarified some details of structure and faunal palaeogeography. Woodcock’s (1990: fig. 7) inclusion of Grangegeeth in between the Lake District and SE Ireland as part of the Leinster Basin is a misconception that has been promoted in several papers of the last few years involving models of Iapetus development and closure, e.g. McKerrow & Soper (1989), Hutton & Murphy (1987).

Our intention, therefore, is not to criticize the interpretation of Woodcock (1990), but to point out that pertinent information has been overlooked, and also that new work concerning the Grangegeeth terrane is in press.

Harper & Parkes (1989) summarized the palaeontological constraints on the definition and development of Irish Caledonide terranes. Concerning Grangegeeth, the old provincial assignment to Baltica was dismissed, since Productorthis, the most diagnostic genus of Williams (1956) is known from contemporaneous Laurentian rocks. Overall, in the light of improved information on brachiopod distributions, the Grangegeeth assemblages show a strong Scoto-Appalachian affinity, as do the trilobites (Romano et al. 1990 & pers. comm.). This is a major contrast to the Caradoc brachiopod signature from the Leinster terrane which is part of an Eastern Avalonia centred Anglo-Welsh faunal province (Parkes 1990Parkes 1991). The Bellewstown terrane, also in the suture zone, has an

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