I sedimenti del lago Van: archivio climatico e ambientale degli ultimi 600.000 anni
Presenta: Luigi Vigliotti, ( CNR-Istituto di Scienze Marine – ISMAR Bologna )
International Continental Scientific Drilling Program (ICDP) drilled a complete 220 m long lacustrine sequence deposited during the last ~600,000 years in Lake Van, the fourth largest terminal lake in the world on a high plateau in eastern Anatolia, Turkey. The target was to investigate the paleoclimate history of a sensitive semi-arid region between the Black, Caspian, and Mediterranean seas. As a closed and saline lake, Lake Van react very sensitively to lake level changes caused by any alterations in the hydrological regime in response to climate change. The detrital signature of the sedimentary sequence, possibly of eolian origin, shows a lithologic variability that reflects changes in depositional conditions, including intervals characterized by anoxic conditions similar to the present-day. The lithological pattern, geochemical proxy records (TOC), elemental scanning (XRF) and even rock magnetic parameters matched the last six orbitally driven glacial/interglacial cycles as well as the sub-orbitally driven climate cycles observed in the Greenland ice-cores. A correlation is also observed with different climatic archives including the record of the dust flux from Antarctica (Epica) and the chinese loess. The unique setting of Lake Van, which records simultaneously the volcanic as well as the earthquake history, also allowed to establish possible coincidence between larger earthquakes and volcanic events.
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