Middle and Late Holocene dry climatic events in the Central Zagros

Climate, as the average temperature or precipitation over a long period of time, is constantly fluctuating and changing. There is a complex relationship between climate change and human biological and cultural reactions (Weeks and Petrie, 2018). Increased dry conditions in the subtropics is one of the consequences of climate change that has been predicted by various models. While using the results of various paleo climate archives can reconstruct the climatic conditions of the past several thousand years and provide more accurate forecasts for the future. Due to the fact that the physical and chemical properties of sediments have an extraordinary power in recording climatic and environmental events with high sensitivity, so the use of sedimentary geochemical results in identifying and reconstructing the effects of dry climatic events is one of the most common method (Sai, 2004).

In order to identify and reconstruct the Middle and Late Holocene dry events, a 2-meter sediment core was used from the middle part of Heshilan marshland. The coring was performed using a Russian coroner. In this study, 5 samples were analyzed by radiocarbon method (C14-AMS) at the Institute of Physics and Astronomy, University of Aarhus, Denmark. Magnetic susceptibility measurements of the samples and measurements were performed using a COX Itrax CS37 scanner at the Bartington MS2C magnetometer at the Geogenetics Laboratory of the Copenhagen Geological Museum in Denmark. The magnetic susceptibility of the samples was measured with an accuracy of 5 mm and the Itrax analysis with an accuracy of 1 mm.

The study of climatic events of the last six thousand years showed the fluctuation of climate between cold, dry and warm phases in the study area, which was consistent with the climatic events of the northern hemisphere. The results showed that dust storms occurred in the period of 5400-5200, 4850-4700, 4200-3700, 3400- 3250, 2300-2100 and 1700-1500 years ago in the region. The length of the region's dry climatic periods has often been 200 years. The longest dry period identified in the region dates back to 4200-3700 years ago.