ارائه مدل مفهومی- چینه ای نهشته های کواترنر شمال دریاچه ی ارومیه با استفاده از GMS (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
نهشته های کواترنر به عنوان منابع اصلی تأمین کننده ی آب شیرین برای بشر محسوب شده و همیشه تحت تأثیر فعالیت های انسانی از قبیل کشاورزی، صنعت، غیره قرار داشته اند. مدل مفهومی نشان دهنده ی ابعاد و جهت و چگونگی گسترش نهشته ها است. در پژوهش حاضر مدل مفهومی- چینه ای نهشته های کواترنر دشت تسوج واقع در شمال دریاچه ی ارومیه تهیه شده است. مدل بر اساس 28 لوگ زمین شناسی چاه های مشاهده ای و 78 سونداژ ژئوالکتریکی در نرم افزار GMS تهیه شده است. بر اساس مقاطع ژئوالکتریک 5 کلاس چینه ای برای نهشته های کواترنر دشت تسوج تفکیک گردید، که شامل نهشته های آبرفتی Qal، نهشته های خشک Q3، نهشته های آبرفتی دانه متوسط (احتمالاً حاوی آب) Q2، نهشته های آبرفتی ریزدانه (احتمالاً حاوی آب) Q1و رس Qmf هستند. نتایج نشان می دهد، نهشته های کلاس Q2از نفوذپذیری متوسط برخوردار بوده دارای سفره ی آب زیرزمینی شیرین هستند، گسترش عمده ی این واحد در نواحی شرقی و جن وب شرقی می باشد. بیشترین فراوانی نهشته های Q3و Qal در ارتفاع 1320 متر بوده ولی ضخامت بالا در ارتفاع 1550 متر با ماکزیمم 190 متر است. این نهشته ها از یک گسترش افقی سرتاسر برخوردار بوده لکن گسترش عمودی آنها بیشتر در نواحی شمالی دشت به خصوص شمال شرقی است. از خصوصیات این واحد نفوذپذیری شدید، عدم وجود ناخالصی های رسی در آن می باشد.Conceptual-Stratigraphic Model Development of Quaternary Deposits in the North of Lake Urmia Using GMS
Quaternary deposits as the major sources of fresh water for humans have often been influenced by anthropogenic activities such as agriculture, industry, and the like. The Tasuj plain is located in 45°18 to 45° 32 E and 38°20 to 38°24 N in north of Lake Urmia in East Azarbyjan province. This plain is one of the sub-basins of Lake Urmia which is surrounded by 12 major plains. The Tasuj basin is about 558 km2. This includes 302 km2 of the Tasuj plain and 256 km2 of Mount Mishu. The study area is surrounded by Lake Urmia (south), Mount Mishu (north), the Salmas Plain (west), and the Shabestar Plain (east). The highest elevation of the Tasuj basin is 3,133 m above the sea level (amsl) at the Peak of Mount Alamdar and the lowest elevation is 1,274 m near Lake Urmia. In the Tasuj basin, only a few seasonal rivers, originating from Mount Mishu, may appear. These seasonal rivers can flood the Tasuj plain in wet seasons. The seasonal rivers are the Amestejan, Angoshtejan, Almas, Chehregan, Tiran, Cheshmekonan, Sheikhvali, Sheikhmarjan, and Ghelmansara. Methodology The conceptual model represents the dimensions, directions, and circumstances of the distribution of the deposits. This research was based on the stratigraphy, the conceptual model of Quaternary deposits of the Tasuj plain, north of Lake Urmia. This simulation was carried out using the GMS software, based on 28 geological logs of observation wells and 78 geoelectrical sounding per geoelectrical sections. The application menus of this software including GIS, TINs, Solids, Boreholes, 3D Gride, and 3D scatter point were used in the research. Results and Discussion Quaternary deposits of the Tasuj plain were divided into 5 classes of strata, including (Qal), (Q3), (Q2), (Q1), and (Qmf). The results showed that Q2 deposits had an average permeability and contained fresh water aquifer in the eastern and southeastern areas. Although Q3 and Qal were located in 1320 m above sea levels (asml), the highest thickness (i.e., 190 m) was shown in 1550 m asml. These deposits spread horizontally in the whole area, but its vertical expansion was more in the northern and, particularly, in the north eastern areas. Q3 and Qal classes were characterized by high permeability and lack of clay. Conclusion The results of this study indicated that the conceptual-stratigraphic model has high efficiency in identifying the Quaternary deposits. The 3D-capable model can expand the point wise characteristics and thickness of Quaternary deposits in the study area using interpolation method. Quaternary deposits of the Tasuj plain were characterized as alluvial deposits (Qal), dry deposits (Q3), medium grain alluvial deposits (possibly water bearing) (Q2), fine grain alluvial deposits (possibly water bearing) (Q1), and clay (Qmf). In addition, the conceptual-spatial model of the quaternary deposits of the Tasuj aquifer showed that aquifer bedrock in the Galemaraghoosh-Shikhvaly was lower than other areas along the coast. There might be a buried deep valley from Almas to Tasuj, Galemaraghoosh.
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