Trace Element Geochemical Correlation in the Reworked Proterozoic Dalradian Metavolcanic Suites of the Western Ox Mountains and NW Mayo Inliers, Ireland

Abstract

Summary Metavolcanic rocks occur within late Proterozoic metamorphic successions in the NW Mayo and western Ox Mountains inliers of western Ireland. Geochemical studies have shown that most of these basic metavolcanic rocks have continental tholeiite affinities, and have confirmed that most form separated portions of the same suite. Within the Ox Mountains Succession, which forms the western part of the Ox Mountains Inlier, all but the Callow metavolcanics can be correlated with those in the NW Mayo Inlier. Thus the Ox Mountains Succession itself can now be equated with rocks in the NW Mayo Inlier, which have in turn been correlated with the late Proterozoic Argyll Group of the Dalradian Supergroup. By contrast, the Callow metavolcanics show affinities with amphibolites from the Westport Inlier and the Kill Inlier on Clare Island, and all have a chemistry consistent with extrusion in an ‘oceanic’ setting similar to some metabasalts from the Scottish Highland Border Complex. These correlations revealed by geochemical studies have important implications for the interpretation of the former positions of discrete terranes within the Caledonide orogen in Ireland, and illustrate the value of geochemistry in resolving stratigraphic problems in complex areas.