بررسي آثار برف مرز دائمي يخچال هاي كواترنري توده كوهستاني قروه

The Quaternary Evolution of Kurdistan Qorveh Mountain Mass

فرم زمين نتيجه نهايي ساختمان اوليه زمين و فرايندهاي اثرگذار در طي زمان است. براي بررسي اثر ساختمان اوليه بر پالئوهيدروژئومورفولوژي، نواحي كوهستاني قروه انتخاب گرديد كه دليل آن تسلط فرايند يخچال كواترنري با توجه به عرض جغرافيايي بالا و ارتفاع بيش از 3000 متري قله هاي منطقه مي باشد. بر اساس روابط موجود، بازه زماني روزهايي كه احتمال وقوع يخبندان در طول سال، بيش از 170 روز است برآورد گرديد؛ اين مسئله علاوه بر تاييد برودت كنوني هوا، مي تواند دليل ديگري بر تسلط فرايندهاي يخچالي كواترنري باشد. با استفاده از نقشه هاي توپوگرافي 1/50000 منطقه 34 لندفرم سيرك مانند شناسايي شد. روش رايت با توجه به ارتفاع مرتب شده آن ها به صورت نزولي، برف مرز دائمي كواترنري دو دامنه (شمالي، جنوبي) را در ارتفاع 2200 متر نشان ميدهد. بر اساس اين ارتفاع و نقشهي هم دما و هم بارش كنوني، كاهش دماي كواترنري نسبت به امروز حدود 8/8 درجه سانتي گراد و بارش گذشته در حدود دو برابر شرايط كنوني برآورد گرديد. نقشهي هم دما وهم بارش كنوني با استفاده از اطلاعات ايستگاههاي موجود اطراف و داخل حوضه و دادههاي ارتفاعي منطقه تهيه گرديد. برخلاف تحقيقات قبلي، تفاوت چنداني بين ارتفاع برف مرز دامنه هاي مختلف ناحيه كوهستاني قروه وجود نداشت. مورفولوژي و ليتولوژي غالب سيرك هاي قروه در نقشه هاي توپوگرافي و زمين شناسي حاكي از آن است كه در دو طرف كوهستان قروه فرمهاي اوليه كراتر مانندي موجود بوده و چاله هاي مساعد با ارتفاع يكسان، براي تجمع برف و يخ به وجود آورده و همين امر در يكسان بودن ارتفاع برف مرز كواترنري دو دامنه اثر گذاشته است.

Quaternary glacial and interglacial conditions were alternately and they left geomorphological evidence overwhelming that it can be used to determine the extent of glacier and snow-borders and the study of climate change last period. It is possible due to the fact that external processes such as weathering، water erosion current and range motion could not eliminate the debris of Quaternary glacial erosion completely. Form cirque is a reflection of the topography and geology، the type and duration of glaciers. Structure stone، cracks and gaps is an important factor in a cirque cliffs and deep of cirque basins. When in the mountain، peaks height exceeds a little limit permanent snow، glaciers often in cirques. The study area lies on the political sphere three provinces of Kurdistan، Kermanshah and Hamadan between 34.752 to 35.223 latitude and between latitudes 47.411 to 47.416. Initially north-eastern and south-western slopes of the Qorveh mountainous region was divided to Wright method. Altitude، which was 60% of cirque higher than، was considered as the permanent snowline altitude after identifying and counting cirque area of the curved lines form and sort them in descending. The position، height and geomorphological features around the cirque were identified. Snow line was estimated height of 2،200 meters on the total area of this method، and it was not much different on the northern and southern slopes. The altitude of more than 60% of cirque were the height of 2200 meters in both slope. 1.Materials and methods The method is based on the present conditions Hydro-geomorphology state of minimum temperature during the Quaternary through the legacies of morphological climate changes in the Quaternary in the mountainous region Qorveh. Although the place is cold and semi-arid regions of the country due to the current temperature and precipitation conditions، but experienced cold and frost likely transition phase to warm phase cold during the Quaternary. Accordingly، is used primarily method documents the library has and field. Results and discussion: Permanent snowline altitude was estimated of 2200 meters due to the dispersion cirque and Wright method. Analysis of the current isotherm map shows the annual average temperature this height of 8.8 ° C. This is the height of a lower temperature than the average temperature of current regional during the Quaternary. Average Quaternary temperature has been -0.12° C. But in this area there is an obvious difference in quaternary permanent snowline in the North East and South West and this is in contrast to research results that suggest the snowline altitude difference in such domains. 1. Conclusion، Keywords The land surface of the slope aspect influence is undeniable on the durability snow and feeding more glaciers in mountainous regions temperate areas of the Earth's، but this effect certainly cannot be justified only with snow border. Mountain sinuosity altitude difference، the slope of the lower areas of the mountain sinuosity، extent and dimensions of the cirque and who to cirque associated with low levels of around two domains are factors that should be considered in this impact. Morphology and dominant lithology Qorveh cirque on topographic and geological maps show both sides of the Qorveh Mountain their primary form of crater-like and holes with the same height، conducive to the accumulation of snow، this has affected the ice and snow on the same quaternary snow line in two domains. In fact، early topographic conditions that follow the form tectonics، the formation of more than 60% of the cirque at a height that is known today as the permanent snowline altitude (2200 m).