DEVELOPING A IRISH TEPHROCHRONOLOGICAL FRAMEWORK FOR THE LAST GLACIAL-INTERGLACIAL TRANSITION (LGIT; 14-9 KA 14C BP)

The last glacial cycle drew to a close in a series of very abrupt and pronounced climatic oscillations, terminating in a sustained shift to warmer conditions at the start of the present (Holocene) interglacial. High-precision correlation of ice, marine and terrestrial sequences from this period is hampered by problems inherent in radiocarbon dating, especially because of marked fluctuations in atmospheric 14C content. Tephrochronology offers the potential to solve some of the geochronological and correlation problems, because it provides time-parallel horizons that can test ideas about the correlation of sequences independently of the radiocarbon method. It can also be used to establish the magnitude or errors associated with the radiocarbon method. Recently, innovative new approaches have been developed for the detection of tephra horizons within sedimentary sequences that are not visible to the naked eye (microtephra or cryptotephra horizons). As a result, the provenance of known eruption events have been significantly expanded. Furthermore, these methods have led to the detection of previously unidentified eruptive events, which increase the scope for using tephrochronology for correlation purposes. Here we report on the application of these approaches to the investigation of LGIT sites in Ireland. Data are presented for three LGIT sequences in Northern Ireland: Roddans Port, Long Lough and Loch Nadourcan. Several tephra horizons have been detected, some of which are new finds for the British Isles. The potential for correlating Irish palaeoclimatic datasets to those developed throughout the North Atlantic region will be discussed.