Jalilian t., T.,
Lak r., R.,
Taghian, A.,
Darvishi khatooni j., J. International Journal of Environmental Science and Technology (17351472)19(3)pp. 1555-1572
Gavkhouni Playa, as lowland of the Zayandehrud River catchment area, is located in an inter-mountain basin in Central Iran. A total of 16 sedimentary cores were taken from the inner and outer parts of the basin, and surrounding areas to investigate depositional systems of the Gavkhouni Playa during the late Quaternary. Sedimentary facies were identified based on sedimentary texture, type of evaporite minerals, presence of organic materials, color changes, and other microscopic characteristics, and sampling was performed based on changes in types of sediment and sedimentary facies. A total of 80 sediment samples were selected for granulation analysis by two methods of wet sieving for coarse-grained particles and Laser Particle Sizer Analysette for smaller than sand (silt and clay) particles. Sedimentology parameters were measured by the Sedilizer software, and the results were statistically analyzed by the SPSS software. The major types of sediments in the Gavkhouni Playa sub-surface, mud and sedimentary environments included aeolian, fluvial, deltaic, lacustrine, and playa environments. According to 14C-AMS isotope dating analysis, the sedimentation rate for 40 ka period, is about 0.4 and 0.25 mm in western and eastern parts per year, respectively. Paleogeography of the Gavkhouni Playa and its extent have been reconstructed for the last 40 ka BP. The results showed that the Gavkhouni Basin extended to the western part of sand dunes during the late Pleistocene. During the early-middle Holocene, coastline regression and the Zayandehrud Delta progression toward the playa occurred in the northern part of the area. During this time, aeolian sands spread to the Gavkhouni Playa. In the Late Holocene, arid conditions caused a decrease in water level and coastline regression along with the domination of the playa environment in the Gavkhouni margin. But, there were still ephemeral lake conditions in the center of the Playa. Gavkhouni Playa experienced an increase in the level and progression of the coastline towards land about 3000 years ago. The presence of arid conditions about 1000 years ago (cal. BP) changed the Gavkhouni lands into a playa environment, and this situation was dominant in the area almost to the present day. © 2021, Islamic Azad University (IAU).
