NORTHWEST EUROPEAN PALEOCLIMATE AS INDICATED BY GROWTH FREQUENCY VARIATIONS OF SECONDARY CALCITE DEPOSITS

A compilation for the northwest of Europe of over 500 uranium-series speleothem and travertine dates is presented using a cumulative distributed error frequency approach. These secondary carbonate deposits require both significant groundwater supply and a biogenic soil carbon dioxide source for their growth. During glacial periods Soil CO2 production is inhibited and the water supply is ice locked, therefore growth is slowed significantly if not stopped. Thus deposits can be used on a chronological basis to give a signal of glacial and non-glacial periods. However, sensitivity to the groundwater supply modifies this signal, with growth also limited in times of high aridity, the palaeoclimatic signal is thus complex. The compilation presented is used both as a chronology for comparison with the orbitally tuned marine oxygen isotope record, and as a palaeoclimatic indicator. Attention is focused on two periods of the last glacial/interglacial cycle where the record provides a significantly different palaeoclimatic record to other terrestrial and oceanic records. These are the isotope stages 5/4 transition, for which a relatively low cumulative growth frequency indicates an earlier increase in aridity than observed elsewhere, and isotope stage 3, the pleniglacial, where both statistically significant high (49-62 ka) and low (22-35, 44-46 ka) levels of growth are observed, and can be used to constrain the timing of many of the interstadial and stadial events within this period.