New high-precision U–Th dates for speleothems from the Assynt caves and their significance for past environmental change

The Late Quaternary climatic history of substantial parts of Scotland remains poorly understood because much of the sedimentological record that might have provided evidence has been erased by glacial and post-glacial erosion. Here we report 19 U/Th dates obtained from archived speleothem samples from Assynt, NW Scotland. We used state-of-the-art MC-ICP-MS U-series dating and find that speleothem deposition in Assynt was restricted to warm periods when the surface was ice-free and continuous permafrost absent. Our dataset reveals significant speleothem deposition during the Ipswichian (Marine Isotope Stage 5e) and the Holocene (MIS 1), and the formation of thin flowstone sheets during Greenland Interstadials 14 and 12 during the last glacial period. These dates highlight the potential for the use of speleothems to constrain the timings of regional glacial and periglacial conditions, and for the reconstruction of interglacial and interstadial environmental dynamics in Scotland.