Senckenberg Research

Analysis of lacustrine sediments from Lake Chatyr Kol (Kyrgyzstan)

Two continuous composite profiles of more than 6 m length each from Lake Chatyr Kol in Kyrgyzstan, drilled in summer 2012, cover, according to the present age model, the complete Holocene back into the Late Glacial. The consistently finely laminated sediments, in combination with the highly seasonal climate, suggest that the predominant part of the succession is annually stratified. This not only allow to establish a precise age model, which is produced by a combination of varve chronology and physical age determinations (14C, 210Pb, 137Cs), but also a high-resolution study of the dynamics of environmental and climate changes.

The two profiles are characterized by an ideal sediment composition with a high concentration of biomarkers that are necessary to determine temperature proxies by alkenones and GDGTs. The analysis of hydrogen isotopes on terrestrial and aquatic biomarkers allows the determination of water sources as well as evaporation in the catchment area of the lake. Furthermore, aquatic bioindicators (fossils of small aquatic organisms such as diatoms, chironomids and ostracods) are used to reconstruct former limnological and climatic changes by analyzing carbon isotopes and quantitative changes within microfossil communities. Thus, hydrological events can be precisely determined within the varved succession and possibly correlated with marker layers in laminated sediment sequences from other localities in the region.

The results of the different climate proxies will be combined in order to detect tipping points and thresholds for changes in the lake system.