Uranium series dates from the windy pits of the North York Moors, United Kingdom: implications for late Quaternary ice cover and timing of speleogenesis

摘要

Windy pits are open fissures within the Corallian strata of the North York Moors. Here we present nine thermal ionization mass spectrometry (TIMS) U-Th dates on speleothem from the windy pits, the first radiometric dates on calcite for these features and for this region. The dates cluster within three time periods: the interglacial peaks of marine isotope stage (MIS) 7 (similar to 208 to similar to 190 ka), MIS 5 (similar to 127 ka to similar to 109 ka) and the Holocene, correlating with the marine isotope record and with the broad pattern of interglacial calcite deposition observed for northern England. However, of the two high-resolution studies available for comparison, the windy-pit dates match only the Lancaster Hole dates. The location of the windy pits outside of the Devensian ice limits, within the ice-free but periglaciated region, suggests that the region has remained ice-free since some time before MIS 7. The prevalence of widespread and prolonged permafrost conditions suggests a plausible mechanism for these open rift caves in slope-side periglacial mass movement. Copyright (C) 2008 John Wiley & Sons, Ltd.