Investigation of the last Quaternary climate from the geomorphic evidence in Namak Lake basin, Central Iran

Abstract

Two important characteristics, alternate climatic oscillations and the appearance of human beings, distinguish the Quaternary from other geological periods. The climatic changes have shown increases and decreases of glacial scope in high latitudes, but there are different and opposing theories about the climatic situation in glacial periods of low latitudes such as Iran. In this study, the climate of the last glacial period of Namak Lake basin, located in north central Iran was investigated by using the past geomorphic evidence and statistical analyses. The present temperature and rainfall of this basin were studied and its related displacements were plotted, as were glacial cirques and lake terraces as geomorphic evidence. Regarding the snowline at different points of the basin, the temperature and rainfall of the basin in the Wurm glacial period was rebuilt by the Wright method and the changes relating to the present time were studied. Morphogenetic plans of the basin in two periods were prepared by using annual rainfall and temperature, and the Peltier method. Results show an increase of 48% (180 mm) in the annual rain and a decrease of 5.6°C in the Wurm glacial period compare with the present temperatures. The geomorphic evidence of the climatic changes including the Namak Lake terraces, travertine mines; vast areas of pediment and the effects of human civilization have yielded proven results. Key words: Quaternary, holocene, morphogenetic, climate change, Namak Lake.