Recovery of sequences and extent of ancient lake in Jazmourian Playa based on lake terraces in Quaternary

Extended abstract 1-Introduction The natural environment is affected by climate, and its changes have different geomorphic forms. The dominance of different climatic phases and changes in the balance of matter and energy cause different shaping systems in the environment. Ancient lakes are one of the geomorphic forms of the Quaternary period, and today many of these lakes are either completely dry or have temporary and sometimes permanent lakes. One of the major functions of geomorphologists in studying ancient environments is to identify and map the shores of ancient lakes that show hydrological changes from wet to dry conditions. These studies are based on the height of lake terraces by reconstructing the volume and dimensions of ancient lakes and studying climatic conditions. Terraces are one of the best evidence of the reconstruction of ancient paleo geomorphological conditions in the coastal environments of the seas and lakes because the water level fluctuation and, consequently, the advancement and regression of water have created them on the coast. By examining the number of terraces, different periods of climate change can be identified, and changes in the extent of lakes can be determined.   2-Methodology This research has been done using the library, field, laboratory, and software studies. After visiting the area, lake terraces were identified for the first time in the area. In the next step, samples taken from these surfaces were analyzed in a laboratory, and their lake nature was confirmed. Then, using remote sensing and mapping techniques based on the height of the recorded lake terraces, the lake area levels were determined, and finally, the limits of these levels were corrected according to other natural factors such as slope, aspect, drainage pattern, and geological studies.   3-Results In the Jazmourian region, according to geomorphological evidence, three levels of lake terraces remain, the first of which is located in the west of the current Jazmourian plateau at an altitude of 410 meters above sea level and shows a lake with a depth of 72 meters and an area of ​​11935 square kilometers in the past. It shows that this level is the highest level of an ancient lake in the region that has been identified. In the western part of the hole, the second level of the garrison is located at an altitude of 375 meters above sea level and shows a lake with a depth of 37 meters and an area of ​​6579 square kilometers in the past. It separates from the previous terrace and shows a lake with a depth of 32 meters and an area of ​​5486 square kilometers, which was the lowest limit of the ancient lake, according to the evidence identified in the area. Different climatic conditions in each period in the region have created a different lake area. In fact, in favorable periods, there were lakes with more area and less water salinity, and in unfavorable weather conditions, in terms of rainfall characteristics, the lake was formed with less area and more salinity.   4-Discussion & Conclusions The results show that three levels of terrace in Jazmourian Playa at different heights in the west of the current seasonal lake, which indicates different climatic periods and the expansion of the lake in the past, were identified, and the extent of the ancient lake in this area was restored. Krinsley (1972) proved the past wet conditions in Iran by studying aerial photographs and field observations based on geomorphological, hydrological, and tectonic evidence in Iranian beaches. His studies show that there was a large lake in the Jazmourian hole in the Ice Age with varying width and depth, which is confirmed by the results of this study. Vaezi et al. (2019) also examined the evidence of climate diversity in the Pleistocene-Holocene period based on various geochemical analyses. Their results confirmed the regionchr('39')s wetter climatic conditions in the past, which is consistent with the results of this study. Of course, the lack of financial facilities for dating terraces and determining the exact time of the lake is one of the main problems of paleogeomorphological studies in the world and this research. Iran should be eliminated.