A study on the Salt (Urmia) Lake in northwest of Iran focused on sediments lakebed

Abstract

Lake Urmia, as the largest and saltiest permanent lake in Iran, being also known as one of the world’s
largest and saltiest lakes, has emerged after the last glacial period due to the tectonic activity of
compressive faults specially Tabriz and Zarrineh-Rud faults in the northwest of Iran. This relatively
young lake has stone foundation being composed of limestone and marlstone without any folding
(Qom Formation) in Miocene Epoch on which about 30 meters of soft lake sediments are deposited.
More than 80% of these deposits are chemical and evaporative along with mainly aragonite, calcite,
and halite minerals with biological origin. The presence of clastic thin layers consisting of quartz,
feldspar and kaolinite, especially at the entrance points of the rivers, indicates temporary climate
change and lake salinity. The thickness of the evaporitic sediments has remarkably increased with
depth decrease in the southern part of the lake along with the increase in evaporation, causing the
emergence of more than 56 small and large islands in this part of the lake. Succession of evaporitic
sediments in some parts of the lake has deposited sulfate minerals such as gypsum and anhydrite in
very fine shapes. In addition, in the swampy areas of the lake, sulfur sediments can also be seen as
sedimentary laminates.