Mississippian microfloras from the South Munster Basin, Ireland

The Lower Carboniferous (Mississippian) succession of the South Munster Basin comprises a thick (2.5km) succession of shallow to deep marine clastic sediments. Lithostratigraphically these rocks are referred to as the Cork Group and have been divided into four formations in the South Cork Sub-basin and into five formations in the West Cork Sub-basin. Biostratigraphically the succession has been dated using miospores, conodonts and goniatites. However, the latter two fossil groups only occur intermittently throughout the succession, whereas miospores are abundant throughout. Detailed palynological studies have recognised a continuous succession of miospore assemblages which can be assigned to the Carboniferous miospore zonation scheme for northwest Europe (CLAYTON et al., 1977). The base of the Kinsale Formation contains the LN/VI miospore biozonal boundary which correlates closely with the base of the Carboniferous system. The Kinsale Formation and overlying Courtmacsherry / Reenydonegan Formations (Members 1-3) have yielded relatively well preserved miospores of early to late Tournaisian age (VI-CM Biozones). Member 4 of the Courtmacsherry Formation contains poorly preserved miospores of early Vis_an (Pu-TC Biozones) age. The overlying Lispatrick Formation contains very poorly preserved and low diversity assemblages of mid to late Vis_an age (VF °V CN (Cc Sub-biozone) Biozone). The White Strand Formation of the South Cork Sub-basin and the East Point, Middle Battery and Kilmore Formations of theWest Cork Sub-basin contain slightly more diverse and better preserved miospore assemblages that are Serpukhovian (early Namurian) age (upper CN (Vm Sub-biozone) - SO Biozones). The taxonomic diversity and preservational quality of the miospore is highly variable, particularly from the upper part of the succession. This is due to both the high thermal maturity of the organic material and to the anoxic environment of a starved deep marine basin.