Abstract

M.D. Max and J.A. Winchester write: Kennedy & Menuge have proposed that the Inishkea Division in the northwest part of the north County Mayo metamorphic inlier is part of the Dalradian Supergroup, containing beds as young as Islay Subgroup. We disagree strongly.

Kennedy & Menuge followed the geological subdivision of the Caledonian rocks in the inlier proposed by Max (1970), Sutton (1971a, b), Crow et al. 1971, Crow & Max (1976), Max & Long (1985), Winchester & Max (1988a, b) and Max et al. 1992, and the results of isotopic dating summarized by Aftalion & Max (1987) that show the long pre-Caledonian tectonothermal history of the Annagh Division gneisses.

However, the relationship of the Inishkea Division, linked with the Annagh Division as part of the Erris Complex (Winchester & Max 1988a, b), to the Dalradian is less clear than the relationship between the Annagh Division and the Dalradian. The Inishkea Division does not contain the complex extended early structural history and variety of deformed and metamorphosed igneous rocks displayed by the Annagh Division (Sutton & Max 1969). Even the Annagh Division was then regarded by some as containing no rocks of tectonothermal activity older than Caledonian (Phillips et al. 1969).

Kennedy & Menuge comment that ‘no unambiguous sedimentary structures have been recorded from any rocks assigned to the Inishkea Division’. During the course of field mapping in Mayo (Max et al. 1992), graded bedding, slump conglomerates, heavy mineral beds and bottom compaction sedimentary structures have been recognized, and are especially

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