Investigation of temperature, humidity changes and glacial evidence in the late Pleistocene (Case study: Kona Goorg valley, northwest of Piranshahr)

Investigating the geomorphology of glaciers and the changes in their past climatic conditions is one of the major topics of mountainous territories. The border areas of Iran and Iraq, which are located along the Mako-Bane Mountain range, have many evidences of glacial traces; But due to the border and security situation and the difficulty of commuting, it has been far from the eyes of researchers. This research has been done to investigate the evidence of glaciers in the past climate of Kona Goorg valley in the northwest of Piranshahr by using field observations and laboratory work and reconstruction of temperature and precipitation. Also, the identification of the sequence of new and old terraces in this area and their comparison and correspondence with the terraces of the Zevka river, the main branch of the Little Zab river, have also been investigated.

The data used in this research included topographic maps, Landsat 8 images, climatic data, field observations and sampling. The studied area and elevation data were measured and extracted from 1:50000 topographic maps and during repeated visits with GPS. There were 4 general stages of field operations. The first stage of the field visit includes: identifying and recording the location of landforms, extent of glaciers, identifying evidence of glaciers such as cirques and glacial valleys, moraines and their extent and on the edge of the valleys and taking photographs. has been in the second stage, sediment samples were taken from the Kona Goorg valley and photographed. The third stage was the collection of rock samples, completion of field data and evidence of glacier activity in the Quaternary.

The results obtained by Porter's method, the snow-boundary area of the region is 2563.6 meters, and with the method of the maximum height of lateral moraine, the height is 2571 meters. The temperature and precipitation anomalies are 6.45 degrees Celsius and 233.8 mm, respectively. Granulation of the samples, where coarse and medium gravel make up the largest percentage. XRD test showed that chlorite and illite minerals are the most abundant in the surface sample and kaolin mineral is more abundant in the deep sample. Glacial evidences include layers and outcrops of Brecia stone on the edges of glacial valleys in the form of antidotes, the side moraines are stretched up to a height of 2272 meters. The glaciers in the form of new terraces, which are probably related to the Wurm period, are located on both sides of the valley at a lower altitude, and the old terraces are located at a higher altitude (2606 meters) with a difference of 60 to 80 meters from the valley floor. have height A mass of cemented glacial deposites was observed in the left part of the glacier valley with a length of 570 meters and a width of 180 meters, which probably belongs to the older ice ages. The northern valley of the region extends to a height of 2720 meters and the southern valley to a height of 2686 meters and has preserved its U-shaped shape to some extent. One of the main property of Kona Goorg cirques is its elongated shape. In the northern valley, they extend from an altitude of 2720 meters to an altitude of 2900 meters, with a length of 600 to 700 meters. Three alluvial terraces have been identified on the edge of the river.

In general, evidences and effects of glaciers related to paleoclimate in the study area show that the study area was affected by glacier activity in the late Pleistocene and even in the Holocene. The mountain slopes and especially the edges of the valleys are covered with a huge amount of glacial deposites. Numerous field visits clearly revealed the existence of a sequence of glacial periods. The remains of terraces and glacial drifts at lower altitudes than the glacier cirques show three cross-sections of slope change, which in some slopes are cemented glacial deposites in the middle of piles of new moraine, it has an exterior. These conditions are consistent with the alluvial reservoirs (glacial melt water) of the main branch of the Little Zab river near Mashkan village. These terraces are in line with the findings of Jedari Aywazi's research on the rivers of the lake Urmia basin, which all have 3 to 4 alluvium terraces. is correspond. The granulation and XRD test of the glacial sediment samples confirmed the poorly sorted, angularity and superior volume of the gravel sizes, which is indicative of severe physical weathering. Putting these data together with the reconstruction of temperature and precipitation is indicative of the changes. An increase in precipitation and a decrease in temperature in the past compared to the present.