Evidence of abrupt climate changes in the Near East - half a million years of environmental conditions captured in Lake Van's subsurface
Abstract
Varved sedimentary records have shown their high potential to reconstruct abrupt and global climate change within the marine realm (e.g. Cariaco Basin, Santa Barbara Basin). Continental counterparts, consisting of long and varved lacustrine sediments, can be found in the subsurface of some deep lakes such as Lake Van in Eastern Anatolia (Turkey). This lake is a 440 m deep terminal soda lake situated in a climatically sensitive semiarid and tectonically active region. Through the ICDP project Paleovan, its complete 220 m long sedimentary succession was recovered in 2010. Lithological descriptions, XRF-scanning and sampling for multi-proxy studies are underway since spring 2011. The lithostratigraphic framework of the composite profile, consisting of carbonaceous clayey silt intercalated by ~300 tephra layers, is overprinted by dozens of seismic-related microdeformations. This partially annually-resolved continental sediment sequence is ideal to reconstruct climate, tectonic and volcanic activity in the mid-latitudes over the past 500'000 years. Distinct color transitions and repetitive sedimentary patterns are the expression of sudden and periodic environmental changes. They are also mirrored in high-resolution color data and variations in total organic carbon concentrations, both reflecting lake productivity. First results of absolute age control is provided by single-crystal Ar/Ar dating of tephra layers. It is confirmed by an excellent match of proxy data to marine isotope stages and substages. The abrupt changes observed in the record suggest that climatic, hydrological and environmental conditions prevailing in Eastern Anatolia were synchronous to the Dansgaard-Oeschger (D/O) cycles recorded in ice and marine sediment cores as well as in speleothems from the last glacial period. The presence of this signal in the Lake Van archive indicates a wide-reaching effect of N-Atlantic-controlled climate. Furthermore, analogous evidence of identical sub-Milankovitch climate variability during previous glacials, indicates that similar D/O mechanisms were acting already during previous glacial-interglacial cycles.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMPP31D..02S
- Keywords:
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- 4901 PALEOCEANOGRAPHY / Abrupt/rapid climate change;
- 4914 PALEOCEANOGRAPHY / Continental climate records;
- 4942 PALEOCEANOGRAPHY / Limnology;
- 9345 GEOGRAPHIC LOCATION / Large bodies of water