Sedimentology and mineralogy of Holocene sediments of Hoz-e-Soltan Lake

Geological time has been evaporited sediments form by solar-driven concentration of a surface or nearsurface brine. Large, thick and extensive deposits were dominated by rock-salt (mega-halite) or anhydrite (mega-sulfate) deposits tend to be marine evaporites and can be associated with extensive deposits of potash salts (mega-potash). Examinations of sedimentologic and mineralogic characteristics of the closed-basin cores due to the very high susceptibility to precipitation and evaporation balance are beneficial for determination and evolution of late Quaternary sedimentary specification. Playa defined as an intra-continental arid zone basin with a negative water balance for over half of each year, dry for over 75% of the time, with a capillary fringe close enough to the surface such that evaporation will cause water to discharge, usually resulting in evaporites. The negative water balance includes all sources of precipitation, surface water flow and groundwater flow minus evaporation and evapotranspiration. Hoz-e-Soltan Lake, with 195 km2 catchment area and 25-50 cm depth, locates at 85 km of southwest of Tehran-Qom highway, in Central Part of Iran. It is sited between 34º56´ and 35º31´ north and 50º53´ and 51º20´ east at western-north of Hoz-e-Masileh. The maximum superficial relief is about 1940 m to the north and 1150 to the south. It is surrounded by Ali-Abad and Kushk-e-Nosrat mountains in north and northeast, Manzarieh and Chahar mountains in west and Mohammad-Abad and Badamcheh mountains in south and southeast. Orogenic movements and volcanic eruptions at the end of Cretaceous and early Eocene led to formation of Eocene volcanics in the north and some central parts of Iran, and particularly around the Hoz-e-Soltan basin. As a result of faulting takng place following the volcanism at this area, a graben was formed, which was later filled by the salt Lake. This graben formed a closed basin, which has since become partially filled with interbedded terrigenous-clastic and evaporite sediments. The evaporate facies present conform approximately to a ″tear-drop pattern″. This research was conducted with the aim to determine sedimentary facies and identify evaporate minerals as well as the change in the type of mineral composition within the sediments that were formed during the Holocene period reflecting the balance in water input and output in the studied basin.