نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده علوم زمین، دانشگاه شهید بهشتی، تهران، ایران

چکیده

کوهستانهای رندوله و بابوله در دو طرف یک دره یخچالی بخشی از رشته کوه ماکو – بانه در مرزهای ایران، ترکیه و عراق است. این منطقه از نظر ساختمانی در زون سنندج – سیرجان واقع شده است و از روند زاگرس تبعیّت می کند. این پژوهش با استفاده از نقشه‌های توپوگرافی، نقشه‌های زمین شناسی، تصاویر ماهواره‌ای، داده‌های اقلیمی، داده ارتفاعی، مشاهدات میدانی و نمونه‌برداری رسوب انجام شده است. با استفاده از نقشه‌های‌ توپوگرافی در مناطق یخچالی موقعیت چندین سیرک بزرگ و کوچک شناسایی شد و برف مرز با استفاده از روش رایت محاسبه گردید. مسیر مشاهدات میدانی تعیین و بازدید‌های‌ مکرر از منطقه مورد مطالعه انجام شده است. یافته‌های تحقیق نشان می دهد که خط برف مرز دایمی در آخرین دوره سرد در ارتفاع 2600 متری قرار داشته است و چندین سیرک بزرگ و کوچک یخچالی همراه با دره‌های‌ U شکل و مورن‌های‌ کناری برجای مانده در حواشی دره‌ها  حاکی از شکل زایی یخچالی در آخرین دوره سرد بوده است. با گرم شدن هوا بعد از عصر یخبندان و بالارفتن خط برف مرز، احتمالاً ذوب یخچال‌ها ، جریان‌های‌ سیلابی قوی را ایجاد کرد که سبب حرکت مواد یخچالی و ته نشین شدن آنها در نواحی کم ارتفاع تر شد، که در حال حاضر بستر شهر اشنویه و چندین روستای منطقه را تشکیل می دهد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

The Evidences of Randuleh and Baboulah glaciers on the borders of Iran, Turkey and Iraq

نویسندگان [English]

  • Manizheh Ghohroudi Tali
  • Rasoul Hasani Gharnayi
  • Taher Khorshidi
  • Mehrnoush Heidari

Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran

چکیده [English]

Geomorphological evidences of glaciers have remained of climate changes during the Quaternary period, which is largely dispersed in mountainous areas. Renduleh and Babuleh mountains are located on both sides of a glacier valley in the Maku-Baneh Mountain on the borders of Iran, Turkey and Iraq. The hillslopes of the Renduleh and Babuleh Mountains in the west of Oshnavieh city have recorded many effects of ice actions. Evacuation of destroyed materials and transported by the glacial have formed Oshonvieh city and several villages in this region. In the research, these glaciers were examined.
Case Study
The case study is the part of the Maku-Baneh Mountains in Kordestan Province. The aspect of tectonic is located in the Sanandaj-Sirjan zone and it follows the Zagros trend, but it is conformity to the Central Iran's Stratigraphy.
Materials and Methods
This research, was performed by using topographic maps, scale of 1: 50000 and 1: 25000 Oshnavieh and Naghadeh, geological maps 1: 250,000 scale of West Azarbaijan and 1: 100000 of Oshnavieh and Naghdeh, panchromatic images pixels size 2.5 meters of IRS satellite of India Year 2016 and Landsat 7 satellite images of ETM, climatic data from Piranshahr synoptic stations, Naghadeh and Orumiyeh, Oshnavieh climatology stations and Qasemlou and Pegeland evaporation stations, Aster elevation data from Terra satellite, field observations and sampling of sediments. First, using topographic maps in the glacier areas, the position of several large and small cirques were identified. Based on the extracted cirques, the snowline was calculated using the Wright method and the field observations and visited the regions for several times. In this regard, the effects of the glacial process were identified. The position of the cirques and valleys of the glaciers and the lateral and end moraine were recorded by GPS. In order to study the environmental conditions, 8 sediment samples were taken for granulometric and morphoscopic analysis. The cumulative frequency curves and sorting of grains were calculated and thin sections were prepared from 1 mm to 1.063 micron deposits, and  used for Roundness, angularity and sorting by polarizing microscopy.
Result and Discussion
The results of the survey of panchromatic images, topographic maps and field observations have been determined the position, number and height of the Cirque in the study area. Field observations showed the maximum density of glacier cirques is at 2600-2800 meters and that most of the cirque are located in the north and northeast directions where they received the least amount of energy from the sun. There is a relatively evolved cirque on the summit of Rendeuleh, which is located in the northwest direction, but its glacier valley extends to the southwest. Based on the Wright method, the 60% of cirques are at a height 2,600 meters, so the regular snow line of the area is set at this altitude, which in most places corresponds to the end of the cirques and the glacier valleys. The sediment diagrams have the highest compliance with the parabolic environment and showed weak and poor sorting of sediments. The sediment analysis showed that the samples were graded from a mixture of fine and coarse grains, and the irregularity and sorting were weakened. According to the Convex curvature graphs, the sediment were deposited by streams which not capable of carrying them. The sorted samples taken in the region are numbered more than one such that the A, B, C, E and F samples have a value greater than 2 and the D,G and H sampled has a numerical value between 1 and 2, which, in general, is based on the Folk index, sorting is very bad. Also, the results of morphoscopic studies indicate that the percentage of angular grains is high, which is one of the characteristics of sediments in the affected areas of the glaciers. The results of the morphoscopy of the samples shown that the angular grains in all samples are above 50%, and the rounded are less than 20%.
Conclusion
Renduleh and Babuleh mountainous is located in the west and northwest of Oshonvieh, near the western neighbors. The effects and evidence of glacier condensation and erosion, especially in the northern slopes, are well visible. The research founded have shown that the permanent snow-line was at a height of 2600 meters the last glacial period, and several large and small cirques glacier with U-shaped valleys and lateral moraine in the valleys indicate glacial formation in The last glacial period. In fact the remaining glacier terraces on the left of the northern hillslopes of the Renduleh glacier valley is lateral moraine. A, B, C Samples are located at altitudes higher than the snowline and from the circus and glacier valleys. In the post-glacial period, a large part of the sediments have been transferred to Oshnavieh River by the ice-melting and the Oshnavieh city has been developed on these sediments. The identification of the glacial deposits boundary with respect to their characteristics, in addition to the scientific value of retrieve the glacial past, is important in terms of their relationship with the location of urban and rural settlements and human facilities.

کلیدواژه‌ها [English]

  • Oshnavieh
  • Mako-Baneh Mountains
  • Geomorphology
  • Glacial Sediment