Abstract

G. D. Sevastopulo writes: Clipstone & Roycroft (1992) have argued that the occurrence of muscovite of magmatic origin in Lower Carboniferous (Courceyan; Dinantian) limestones near Kilmaclenine, north County Cork constitutes primary evidence of the presence of now buried granites in southwest Ireland.

Ford et al. 1991 have interpreted the gravity field over the south of Ireland. Their low pass filtered gravity map (fig. 3) shows two large negative anomalies. The first extends southwestward to the neighbourhood of Fermoy, County Cork; Ford et al. interpreted it as the expression of a laccolith, probably the subsurface extension of the Leinster Granite, within the basement to the Upper Palaeozoic. Because of its location within the basement, this laccolith could not have been a source of detrital muscovite during the Dinantian. The second negative anomaly is centred southwest of Killarney. Ford et al. were unable to decide whether it is caused by a buried granite or by an exceptionally thick succession of Devonian sandstone. In their ‘granite model’ (Ford et al. 1991, fig. 6), the main mass of the granite was shown in the footwall of the Killarney–Mallow fault, overlain by Old Red Sandstone and Dinantian limestone. To the south of the fault the granite is modelled as being below the thick succession of Old Red Sandstone, which can be mapped on the Iveragh Peninsula. If a granite was exposed in this region during latest Devonian and Dinantian time, it must have been located in what is now the footwall of the Killarney–Mallow

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