Session 1: Isotopes and biogenic silica: understanding lake sediment archives

Convenors: Phil Barker (University of Lancaster, UK) and Alayne Street-Perrott (University of Swansea, UK)

Melanie Leng
Keynote: Professor Melanie Leng
NERC Isotope Geosciences Laboratory, UK

Palaeolimnology is built on proxies of environmental processes, all of which have different sensitivities and provide different perspectives into environmental changes.  Biogenic silica from lake sediments has become an important host of information regarding catchment silica cycling, and stable isotopes of various elements are now being used to reconstruct climate and biogeochemical cycles.

The IBiS group (http://www.bgs.ac.uk/ibis) is working towards understanding the silica cycle and exploiting the use of isotopes in various forms of biogenic silica to help with environmental reconstruction, especially though not exclusively, from lake sediments. Over the last few years the IBiS working group has aimed to advance techniques in isotope analysis, in addition the community initiated international calibration exercises for both O and Si isotopes. Most recently researchers have moved towards electron microscope imaging and whole-rock geochemistry to enable mass balance approaches to remove contamination effects from the δ18Odiatom record.

With the resolution of many fundamental methodological issues, researchers are now exploiting biogenic silica for O, Si, C and N isotope records to provide environmental reconstructions over the very recent past (last few hundreds of years) to Quaternary time scales. These records have enabled unique insights into climate dynamics from regions where other proxies are not available or insensitive, and the long term functioning of major biogeochemical cycles. We welcome contributions from all working on isotopes and biogenic silica from lake sediment archives and especially contemporary studies that enable calibration of the sediment record.