From open and fresh to closed and alkaline: a history of transforming basins recorded in lacustrine carbonates

• Applicant: Professorin Dr. Ola Kwiecien
• Subject Area: Palaeontology
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 276975625

Inherent features characterising alkaline lakes (basin closure, semi-arid climate, high pH values of water) make them excellent environmental archives. Hitherto several proxy-records from alkaline lakes from across the globe provided outstanding records of past climate change. Our understanding of the chemistry of modern alkaline lakes is based on observation and theoretical modelling, yet the evolution from a fresh to alkaline water body is very rarely documented in the fossil record.Here I propose a comprehensive, carbonate-based pilot study of the initial phase of an alkaline (soda) lake. My archive of choice is Lake Van, an iconic site for alkalinity studies. Existing low-resolution data suggest that Lake Van underwent a significant transition during its early stage. I aim to document, by means of proxy-data, the changes of water chemistry in a transforming basin. My scientific strategy combines the geochemical analysis of lacustrine carbonates (d18O, d13C, Mg/Ca, Sr/Ca) and the oxygen isotopic composition of biogenic silica with ecological studies of ostracod valves.First, these results will enable testing our overarching working hypothesis that Lake Van originated as an open and freshwater basin. Second, they will fill a substantial knowledge gap between scarce observational data and theoretical models. Moreover, with a longer temporal perspective, the results will be placed in a regional climatic and tectonic context, allowing for presentation of a comprehensive proxy-based model of the chemical evolution of an alkaline (soda) lake.

• DFG Programme: Research Grants