Reconstruction of sedimentary environments, climate and water level change of Urmia Lake in the Holocene

Urmia Lake is one of the biggest and salt over-saturated Lakes in the world. It is located at the northwestern part of Iran. This environmental hazard is one of the most significant geological problems of Iran. In this research, 28 sedimentary undisturbed cores having a maximum depth of 9 meters, and totally more than 200 m were prepared by Auger coring method. Fig 1: location of sediment cores Sedimentary facies were separated by color, grain size, sedimentary fabrics and evaporative minerals. With regard to vertical sedimentary facies (from surface to sub-surface areas) changes, geography, climatic conditions and lake water level fluctuation were re-constructed. Facies are from Lake, Lagoon and Mud plain environments. Coring and verification of lake sub environment sedimentary facies indicate that sequential drying up tracks are visible in the coastal areas of Urmia lake. However, the main part of the lake had watery environment (6.5m of the lake floor sediments) for 13000 years. According to the dating by isotope carbon-14 method deposition rate is between 0.7 to 0.8 mm per year, but this rate is varies in different parts of the lake (1.0 to 1 mm per year). Wet years or droughts has direct effect on the various elements in the sediment. According to the proportions of these elements can identified the period of wet years or droughts, according to sedimentary geochemistry. Generally, the many facies and environmen changes at the Urmia lake, is under the influence of climatic, environmental and structural conditions.