Madre de Dios Speleo 2008

Climate Science Methods

In accord with the Chilean National Park authorities, a small number of stalagmites will be removed for climatological study. Stable isotope and trace metal analyses of these samples will form the bulk of the palaeoclimate reconstruction work and radiometric dating will be performed to establish the chronology of these climatic evolutions. Chris Day will be completing this work in conjunction with Professor Gideon Henderson in Prof. Henderson’s laboratories at the University of Oxford and in full collaboration with Drs. Dominique Genty and Richard Maire of the French Ultima Patagonia expedition.

We are acutely aware that damage to caves or the excessive removal of speleothems is unacceptable. Charlie Porter (the boat skipper) has secured permission for us to undertake this scientific study from the Chilean authorities. Scientific work will be conducted in collaboration with the French Ultima Patagonia 2008 expedition to help avoid duplication and to maximise the expedition’s effective contribution. We intend to ensure that we only take a small number of samples (maximum 6) and that we take the most suitable samples for the study. Ideally, samples will come from geographically distinct locations on the island (e.g. north and south) to ensure that their records represent regional climate variation rather than just local influences. Our experience of speleothem work provides us with qualitative means of assessing the suitability of individual samples, thus allowing us to target the most appropriate samples. The most promising samples will be examined further by retrieving a small 15mm diameter core and examining the texture and composition of the internal calcite. These procedures allow us to obtain a maximum amount of climate information with a minimum of disturbance to the cave.

In those caves identified for speleothem sampling, an extensive programme of field measurements and data monitoring will take place that allow us to relate the chemical signatures measured in the speleothem calcite to the general climate of the region. Amongst others, we will undertake a full survey of the explored cave, sample drip waters, measure temperature, pCO2, humidity, and measure modern calcite growth.