Thermal ionization mass spectrometer U-Th dates on Pleistocene speleothems from Victoria Cave, North Yorkshire, UK: Implications for paleoenvironment and stratigraphy over multiple glacial cycles

Abstract

We present 23 new thermal ionization mass spectrometric U-Th dates for Victoria Cave, North Yorkshire, UK. Victoria Cave underwent repeated glaciation during the late Pleistocene and contains one of the longest Quaternary cave sequences in Britain. The dates reveal that speleothem formation began beyond the range of the dating technique (before 600 ka). Finite reproducible dates of 490 −9/+10 ka confirm speleothem deposition during marine isotope stage (MIS) 13, the oldest date we know of for this part of Britain. Further speleothem formation was dated to MIS 11, MIS 9, MIS 7, and MIS 5. The results are the basis for a new chronology of Quaternary events for the cave and greatly enhance our understanding of the factors affecting the formation of the sedimentary sequence. Cyclical climatic and environmental change throughout the late Pleistocene triggered cyclical sedimentation events in the cave. All the interglacial periods show calcite deposition but with growth phases postdating the warmest events of MIS 11 and MIS 5e. The position of the cave halfway up the side of a glacial trough resulted in very distinctive sediment during the more extreme glacial maxima: ice-dammed lakes formed inside the cave and deposited varve-like clay rhythmites. The dates inferred for these deposits suggest that this locality underwent significant glaciation during MIS 12, MIS 10, MIS 6, and MIS 2, and that the ice was warm based. The absence of rhythmites during MIS 8 suggests minimal ice cover at that time. This is the most complete record for glacial events in the region; it is the only site where successive glacial maxima can be identified and dated. The record of large faunal remains indicates that the cave was open to the surface, only for relatively short times, during MIS 13, MIS 12, MIS 5e, the Late Glacial Interstadial, and parts of the Holocene. It is inferred that at other times the cave was closed because scree formation blocked the entrance. The record of vertebrate remains is therefore controlled by geomorphological processes. The deteriorating state of this unprotected site remains a cause for concern.