MASS-SPECTROMETRIC DATING OF FLOWSTONES FROM STUMP-CROSS CAVERNS AND LANCASTER HOLE, YORKSHIRE - PALEOCLIMATE IMPLICATIONS

A terrestrial flowstone sequence 97 cm thick from Stump Cross Caverns, Yorkshire, has been dated by both mass spectrometric and alpha spectr ometric U-238-U-234-Th-230 dating, and is demonstrated to have been de posited predominantly during interstadial periods over the last 170 ka , with no growth in periods of glaciation or within the Oxygen Isotope Stage 5 interglacial. Growth also occurs within Oxygen Isotope Stages 4 and 6, the former possibly correlating with interstadials recognise d in high-resolution ice and ocean-core records. Comparison with the t iming of growth Of a mass spectrometrically dated Lancaster Hole flows tone, also from the same region, demonstrates only limited agreement. These differences are due to two factors limiting deposition at Stump Cross: flooding of the cave passage in warm periods, and the developme nt of continuous permafrost or glacier cover in periods of severe clim atic deterioration. Deposition at Lancaster Hole was controlled by lim itations in ground-water supply rather than flooding of the cave passa ge. The results presented here demonstrate that in addition to regiona l palaeoclimate factors, local site conditions may limit speleothem gr owth. We conclude that in future palaeoclimate studies, the growth rec ord from several coeval speleothem samples must be considered before a regional palaeoclimate interpretation can be made.