Paleoclimate research is largely based on archives - physical records of past climate and environmental conditions. As a Geological Survey, research at GEUS focuses heavily on identifying, selecting, and sampling sediments and rock outcrops, as well as preserving them in optimal conditions until further processing.
1) A regional understanding of the geological and tectonic context. Beginning with the key scientific questions, it is necessary to ensure that the region of interest is best suited and contains a record of the processes and time periods under investigation. Essential methods include onshore geological mapping, onshore and offshore geophysical surveying, development of basin models to understand sources and sinks, paleographic models, and for longer time periods, plate reconstructions.
2) With the regional understanding in mind, specific locations must be identified to determine where the best records are likely to exist. This stage requires collection of new data specific to the sampling targets to optimize the sampling strategy. Essential methods include onshore geological mapping combined with geophysical surveys (esp. EM, gravity, magnetic), deep and high-resolution shallow seismic combined with sequence stratigraphic interpretation, and multibeam seabed mapping. In some cases, this local surveying can be done in conjunction with dedicated sampling, whereas in other cases, a high level of interpretation is required prior to selecting targets.
3) Choosing and carrying out the best sampling strategy. For shorter, more recent time periods, this could include gravity, box, or piston coring, whereas longer records and deeper time would require drilling, or for records onshore, may include outcrop sampling.
4) Having obtained the archive, it is finally necessary to preserve and store the archive for the next steps, which includes dating via biostratigraphic, radiocarbon and other dating methods to establish the timeline recorded by the various proxies. Some records, such as Holocene soft sediments, require temperature-controlled storage, to ensure the preservation of fine sedimentary structures, and sensitive proxies.