Ipswichian fauna of Victoria Cave and the marine palaeoclimatic record

Abstract

The lack of age dating methods which can be applied beyond the limit of radiocarbon dating makes the global correlation of continental climatic events and stratigraphic sequences with the continuous palaeoclimate record, obtained by isotopic and faunal analysis of deep-sea sediment cores^1–3, a difficult task; often only a relative time scale can be obtained using complex and perhaps tenuous litho- and biostratigraphical data. Speleothems may assist in this correlation, for embodied in their calcium carbonate structures are elemental and isotopic variations which indicate both their age and climatic conditions prevailing during their deposition. Speleothems may be reliably dated by the ²³⁰Th/ ²³⁴U method to an age of ∼350 kyr BP providing they consist of non-porous, unrecrystallized calcite which is essentially free of clastic detrital sediments^4–6. They may also provide palaeoclimatic information for previously glaciated areas (1) because their presence indicates that groundwater movement was not prevented by ice formation at the surface, and CO₂ was produced in the soil zone by root respiration and plant decay (limestone bedrock may then be dissolved and reprecipitated as speleothems in caves below the surface), and (2) because of the variations in stable isotopic content and fluid inclusion waters contained therein^4,7,8. Additional climatic and chronological information may be obtained where speleothems are interstratified with deposits characteristic of a particular climatic regime, and with deposits containing organic remains. We describe here the results of dating speleothems encrusting the remains of mammals from Victoria Cave in northern England, and discuss their significance in terms of the correlation between continental and oceanic palaeoclimatic records.