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Introduction: Considering that weather plays an important role in the performance and distribution of lakes, it is difficult to evaluate how climate affects them. More than half of the world's lakes have dried up over the past years.A playa is an intracontinental dry basin with a negative water level. The sediments forming playas are also controlled by the sedimentary processes governing them. Lake sediments are valuable maps of the physical and chemical history of the lake and its facies patterns (Enzel et al,2003,62). Evaporite sediments are valuable sediments for reconstructing climatic, geographical and paleo-oceanographic conditions because they are sensitive indicators of weather conditions and water chemistry. In general, evaporite minerals are formed whenThe amount of evaporation is equal to or more than the amount of water entering the sedimentation basin. With increasing salinity, as a result of increasing temperature, carbonates, sulfates (gypsum) and rock salt (halite) are formed respectively. But detrital minerals enter the basin, feldspars are the most abundant type of these minerals in the earth's crust, followed by quartz. These types of minerals, like quartz, are the main components of many igneous, sedimentary and metamorphic rocks. In this research, the mineralogical status of paleo-sedimentary environments in the subsurface deposits of Jazmurian playa sediments has been investigated in order to investigate the deposition conditions in the past. Research methodology: This research was carried out in Jazmurian play area located in the southeast of the country in the two provinces of Sistan and Baluchistan and Kerman. The method of this research is field, laboratory and analytical method. Research data includes library data, statistical data, visual data, field data, and laboratory analysis. The stages of field studies include initial visit and sampling. Laboratory analyzes have been performed on sediment samples. First, with mineralogical analysis, the type of minerals and their origin are determined according to their deposition conditions in order to analyze the past climate and their deposition environment. Mineralogical analysis has been carried out in the laboratory of the Geological and Mineral Exploration Organization of the country. Also, analysis (TIC TOC-TS-TC) has been used to determine the amount of total organic carbon, inorganic organic carbon, organic carbon and total sulfur in sedimentary deposits. These analyzes were carried out at the CSIC Research Institute under the supervision of the University of Zaragoza, Spain. Results: Based on the field studies and investigation of the width of the playa, the environments and sub-environments of sedimentation in Jazmurian playa are 4 environments, including clay zone, salty zone, swollen and salty zone, central dry zone (seasonal lake). In this research, the findings of mineralogical analysis of two sediment cores show that there are both erosional and evaporite facies in Jazmurian playa. Constituent minerals in this playa include quartz, anortite, clay, calcite, dolomite, gypsum, halite. The amount of destructive minerals in the region is anorthite, followed by quartz and clay. In core No. 1 of Jazmurian, the value of TS, which expresses the dryness and evaporation of the environment, has varied from 0.01 to 0.04. In this core, the amount of TC varies between 2.2% and 0.8%, and among these, the amount of TOC, which indicates the origin of carbon in plants and animals in the environment, is very small, and the contribution of TIC in the sediments of this core is higher. In core No. 2 of Jazmurian, the value of TS in the sediments of this core from the beginning to the depth of 170-180, which is the highest value in this core and shows an increasing peak. The value of TC varies between 0.8 and 1.08. The highest value of TC in this core is related to the value of TIC and the value of TOC in this core is also very low Discussion & Conclusions: Based on field studies and investigation of sedimentation environments and sub-environments in Jazmurian playa, there are 4 environments including clay zone, salty zone, swollen and salty zone and central dry zone (seasonal lake). These sedimentary sub-environments affected by climate change are transformed into each other in the Holocene period. In this research, the findings of mineralogical analysis of two sediment cores show that there are detrital and evaporite minerals in Jazmurian playa. Constituent minerals in this playa include quartz, anortite, clay, calcite, gypsum, halite. The amount of destructive minerals in the region is first anorthite, then quartz and clay. Investigating the mineralogical values in the Jazmurian region shows the climatic fluctuations in the Jazmurian region. These climatic fluctuations have finally faced an increase in the dryness of the environment, which has led to the creation of a salty and shallow lake in the beginning and finally to the complete drying of the lake and the creation of a playa in the current conditions. [ABSTRACT FROM AUTHOR] |
