OXYGEN-ISOTOPE RECORD OF LATE-GLACIAL CLIMATIC-CHANGE IN WESTERN IRELAND

Oxygen-isotope profiles for the Late-Glacial carbonate sediments from Red Bog and adjacent Lough Gur in County Limerick in western Ireland a re readily correlated with the classical biozones delineated on pollen diagrams for the same cores. The estimated summer temperatures of the Bolling/Allerod were as high as those in the early Holocene and are c orrelated with increasing Milankovitch summer insolation. This warm ph ase was abruptly terminated in the Younger Dryas cold episode by a dep letion of 4 parts per thousand, in delta(18)O, suggesting a summer atm ospheric temperature decrease of about 12 degrees C, comparable to tha t inferred from fossil beetle data. The Younger Dryas phase is attribu ted to a major cooling of the sea-surface temperature by a postulated discharge of icebergs similar to that of the Heinrich events, for the icebergs were much more effective than simple meltwater in cooling the sea surface and thus the climate over Europe. Shorter-term cool phase s (Older Dryas, Gerzensee, Preboreal oscillation) are also recognized.