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Thermal groundwater is currently being exploited for district-scale heating in many locations worldwide. The chemical compositions of these thermal waters reflect the provenance and circulation patterns of the groundwater, which are controlled by recharge, rock type and geological structure. Exploring the provenance of these waters using multivariate statistical analysis (MSA) techniques increases our understanding of the hydrothermal circulation systems, and provides a reliable tool for assessing these resources. Hydrochemical data from thermal springs situated in the Carboniferous Dublin Basin in eastcentral Ireland were explored using MSA, including hierarchical cluster analysis (HCA) and principal component analysis (PCA), to investigate the source aquifers of the thermal

The δ 18 O values of phosphatic microfossils recovered from NW Ireland are used to determine the timing and magnitude of cooling associated with the onset of the Carboniferous glaciation. Microfossil fish δ 18 O apatite demonstrates a +2.4‰ (V-SMOW) shift, which, once corrected for δ 18 O seawater changes due to evolving ice-volumes, equates to an approximate 4.5 ºC reduction in equatorial sea-surface-temperature (SST) between the basal Asbian and the mid-Brigantian (late Viséan). Both conodont and microfossil fish δ 18 O apatite indicate stabilisation of an "Ice-House" climate during the Brigantian and into the Serpukhovian. Substantial upper Viséan cooling identified herein is in good agreement with global glacioeustatic records.Supplementary material: Further information on the palaeogeography, lithostratigraphy and palaeoenvironments of the sections examined as well as the sample composition and analytical methodology of oxygen isotope analyses is available at www.geolsoc.org.uk/SUP00000.

Conodonts of the genus Lochriea offer high‐resolution biostratigraphical differentiation of the upper Mississippian (Carboniferous). In particular, L. ziegleri is regarded as the most suitable index taxon for recognition of a revised Viséan–Serpukhovian boundary and selection of a Global Stratotype Section and Point. Mixed carbonate‐siliciclastic Carboniferous sections from western Ireland demonstrate that gradual morphological evolution is expressed within the Lochriea lineage, evidenced by P1‐elements with progressively more complex ornament appearing in a pulsed fashion in the Late Viséan. Significant diversification of the Lochriea conodonts occurs below the currently recognized base of the Namurian (identified by ammonoids), with which the basal Serpukhovian has been correlated in the past. The First Appearance Datum (FAD) of L. ziegleri in the Lugasnaghta Section of western Ireland is apparently coincident with the FAD's of other complexly ornamented Lochriea species (e.g. L. cruciformis) and corresponds with the Irish and British P2a ammonoid biozone and the lower part of the upper Cf6δ (MFZ15) foraminiferal biozone. The FAD of L. ziegleri in Ireland is closely related to other Lochriea morphotypes with complex ornament, which are difficult to identify to species level using current species definitions. These forms, recorded from the three sections examined (St Brendan's Well, Kilnamona and Lugasnaghta), may partly be explained as abnormal growth histories, evolutionary intermediate forms, etc. In some instances, however, the apparently consistent and novel morphotypes suggest that current Lochriea taxonomy needs to be re‐examined. Furthermore, given the close association of the morphologies with asymmetric complex ornament and L. ziegleri, these taxa may hold significance as biostratigraphical tools in their own right.

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