Palynology and palaeoenvironments of the Silurian Coosglass Slate and Ferriter’s Cove formations in the Dunquin Inlier (Dingle Peninsula, Ireland)

Abstract

This study documents the first palynological data from the Silurian of the Dunquin Inlier of the Dingle Peninsula and focuses on the lower part of the succession. The previously undated Coosglass Slate Formation contains a low diversity Llandovery to early Wenlock acritarch assemblage, confirming the previously enigmatic Coosglass Slate Formation as the oldest formation in the Silurian succession. The lithofacies and acritarch biofacies suggest the mudstones of the Coosglass Slate Formation represent a low energy, offshore, muddy shelf palaeoenvironment. The Ferriter’s Cove Formation, a succession of five offshore to tidal-flat regressive marine cycles yielded more diverse palynological assemblages. Acritarchs and cryptospores from the Ferriter’s Cove Formation confirm a Wenlock (Homerian) age for this formation. The integration of palynological and sedimentological data from four of the offshore to tidal-flat regressive cycles reveals three consistent palynomorph distribution trends: (1) offshore and shoreface depositional facies contain the most diverse palynological assemblages in which acritarchs with long and ramified processes dominate; (2) back-barrier tidal-flat facies are characterized by terrestrially derived palynomorphs, particularly cryptospores, together with a restricted acritarch assemblage of mainly micrhystrid and veryhachid forms with small simple processes; (3) back-barrier lagoonal facies with patch reefs are dominated by the sphaeromorph acritarch Leiosphaeridia