Further studies of the validation and simultation of the Lake Urmia minerals exploration process, Report No. 1 (geology and the origin of Brines)
Executor of main plan: Dr Razyeh Lak
Executor of project: Dr Morteza Khalatbari Jafari
Lake Urmia, is the most extended lake in the inner of Iran, and located between western and eastern Azerbaijan provinces. Important rivers such as Barandoz Chai, Nazlo chai, Shar Chai, Zarineh Rud, Shimineh Rud, and Mahabad Rud, are flow over Urmia Lake. The depositions of the Urmia Lake are categorized in two categories: clastic and non-clastic. The non-clastic category has chemical and biochemical in compositions. In the deep of the Urmia Lake, the clastic deposits, including the layers of silts are exposed which composed of clastic minerals, such as quartz, calcite, plagioclase and kaolinite. The clastic deposits are more extended in the entrance of the rivers. In compared to chemical deposits, clastic deposits are less valuable. Non-clastic deposits include aragonite, calcite, dolomite, gypsum, shells, and organic-rich sludge. The origin of Lake Urmia deposits are the geological units which exposed around it. The most important units are Paleozoic carbonate, Cretaceous limestone's, Cretaceous Formations with interlayers of shale, plutonic massifs, volcanic rocks and Neogene Formations. Neogene Formations comprise of a variety of marls, sandstone, conglomerate, gypsum, and salt. In between these rocks, marls, gypsum, increase Lake Urmia water minerals. Recently brine type of Lake Urmia is Mg+2>Na+>K+>Cl- and the value of the Mg is higher than Na. this situation, when created that evaporation rate is higher than surface brines are drying. Field and laboratory investigation of Lake Urmia brines revealed that as the beginning of the evaporation process, the composition of brine was brine Na+> Cl-> Mg+2. With increasing evaporating rate, decreased Na content and increased Mg content. The brine composition is Mg+2>Na+>Cl-, as similar as Karinga playa in center of Australia. It is expected that with increasing evaporation, and more halite deposition, the brine composition will be Mg>SO_4^(-2)>Cl. After Dead Sea, Lake Urmia is the second Saline Lake which has higher salt concentration. This lake with 300 gram per liter of different minerals, like magnesium and potassium, included important economic resources. All available minerals are soluble and salt.