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Climatic Evolution of the Marmara Region during the past 50,000 years

It is proposed that the dispersal of Modern Man (Homo sapiens sapiens) from Africa to Western Eurasia followed at least two pathways. The Collaborative Research Centre (CRC) 806: “Our Way to Europe; Culture-Environment Interaction and Human Mobility in the Late Quaternary” focuses on a Western migration trajectory (via Gibraltar) and an Eastern trajectory (via Levant, Bosphorus). The main task is to entangle the complex nature of chronology, regional structure, climatic, environmental, and socio-cultural contexts of major intercontinental and transcontinental events of dispersal of Modern Man.

The Marmara region (Western Turkey) is expected to have been one of the principal key areas in the transcontinental dispersal of modern humans from the Near East to the Balkans. 

Two prominent time-slices are of particular interest in this area, firstly concerning the primary dispersal of modern humans and the emergence of upper Palaeolithic adaptation (50,000-30,000 yr BP) and secondly dealing with the re-establishment of human habitats after the second glacial maximum and the dispersal of Neolithic economy (15,000-7,000 yr BP). The project B4 in the first CRC phase (2009 -2013) was targeted on reconstructing the climatic and environmental history of the Marmara region since 50 ka.

The project B4 is targeted on reconstructing the climatic and environmental history of the Marmara region since 50 ka and enhancing the understanding of environmental controlling factors for human migration from Anatolia to the Balkan Peninsula. 

Methods

Lake Iznik is located to the east of the Marmara Sea, adjacent to the North Anatolian Fault. According to seismic data, this lake hosts a several hundred meters thick, widely continuous sediment record. Within the scope of the CRC 806, project B4 in 2009 recovered up to 14 m long sediment cores from two sites in Lake Iznik. The sedimentological and geochemical results achieved from these records, as well as from some shorter records cored before, significantly enhanced our understanding of environmental controlling factors for human migration from Anatolia to the Balkan Peninsula. Biological indicators (Cladocera and Ostracoda), in contast, show little response to environmental changes, with the exception of the replacement of the ancient ostracode fauna (Limnocythere-association) by a Candona- association between ca. 1950 and 1990, when woodland was converted to farmland and a more intense farming began.

Despite these results, records of biological indicators (Cladocera and Ostracoda) show little or no response to environmental changes during the last 5000 years. But sedimentological, geochemical and biological proxies in the sediment record synchronously detect intensive changes of land use in the northern farmlands of Lake Iznik, starting around 1950. From 1950 to 1990, woodland was converted to farmland and a more intense farming began. Together with high sedimentation rates more weathered materials were eroded and transported into the lake (K/Na Ratios and Mn concentration; Franz et al . 2006). The ancient ostracode fauna (Limnocythere-association) was replaced by a Candona- association during this short period.