استخراج خطواره‌ها با استفاده از داده‌های ماهواره لندست 8 در پهنه برشی سقز- بانه با تاکیدی بر کانه‌زایی طلا

منطقه مورد مطالعه در جنوب‌غرب سقز و بخشی از زون ساختاری سنندج سیرجان است. این منطقه شامل تعدادی محدوده‌ی کانه‌‌زایی طلا به اسامی قلقله، قبغلوجه، کرویان، حمزه قرنین، قره‌چر و کسنزان است. هدف از انجام این پژوهش، بررسی راستای گسل‌ها و ارتباط آن‌ها با مناطق کانه‌زایی به عنوان معیاری برای اکتشافات آتی است. در این پژوهش با استفاده از تصاویر ماهواره‌ای لندست 8، گسل‌های منطقه با سه روش دستی، اتوماتیک و نیمه اتوماتیک استخراج گردید. در استخراج خطواره‌ها به صورت دستی از چهار روش رایج عملیات فیلتر، مولفه‌‌های اصلی، نسبت باندی و ترکیب رنگی استفاده شد، و با استفاده از نتایج حاصل از چهار روش، یک نقشه خطواره تهیه شد. در استخراج خطواره‌ها به صورت اتوماتیک، از الگوریتم رایج hough transform استفاده شد. در بررسی حاضر، از باند 4 ماهواره لندست 8 که در این باند عوارض زمین‌شناسی مانند انواع سنگ‌ها، مواد معدنی، پوشش گیاهی و غیره قابل تشخیص است، استفاده شد. در روش نیمه اتوماتیک پس از استخراج خطواره‌ها به روش اتوماتیک، خطواره‌های مرتبط به عوارض مورفولوژیکی یا انسانی به صورت دستی حذف شده و بعضی عارضه‌های خطی اضافه شد. نتایج این پژوهش نشان می‌دهد که سه راستای گسلی در منطقه مورد مطالعه شناسایی شد. راستای غالب گسل‌ها، شمال‌شرقجنوب‌غرب است که بخشی از سنگ‌های میزبان کانه‌زایی طلا را در بر می‌گیرد. دومین راستا، راستای شمال‌غربجنوب‌شرق است که به موازات راستای غالب زاگرس است و شامل گسل‌های راندگی اصلی در منطقه است. سومین راستا، شرقیغربی است و بخشی از کانه‌زایی طلا و رخداد دگرشکلی شکنا تا شکل‌پذیر را شامل می‌شود.

Lineament extraction using lansat-8 satellite data in the Saqqez-Baneh shear zone with emphasis on gold mineralization

IntroductionThe purpose of this study is to apply remote sensing technique to extract lineaments in the SaqqezBaneh shear zone. In this study, lineaments were extracted in three manual, automatic and semiautomatic methods and their density and direction as well as their relationship with gold mineralization were investigated.Materials and methodsIn this study, the extraction of the lineaments was performed in two methods, manual and automatic. Then, on the basis that the semiautomatic method has a better advantage than the other two methods, in this research, after extracting the lineaments automatically, the lineaments related to the morphological or human features are removed manually and some lineament are added based on our investigation. In this study, Landsat 8 satellite images, taken on 16/8/2016 in 168 pass and 35 row, were used. Various software including PCI Geomatica (version 2015), Envi (version 4.8), Arc GIS (version 10.3.1) and (rock version 16) were used during this study. Principal component analysis was performed by Envi software and its output image was imported into PCI Geomatica software for extraction of lineaments. Then extracted lineaments were investigated in Arc GIS software and finally the density and direction of the lineaments were plotted by Rock Work software.Results and discussionIn this study, three methods were used to evaluate the extracted lineaments. (1) Lineament density analysis, (2) lineament length analysis, and (3) lineament orientation analysis. The density of lineaments is mostly concentrated in the center of the study area and in the north, west and southwest of Baneh. The density of faults is higher in the center of the study area and in the north, west and southwest Baneh city. Fault, causes pass ways for hydrothermal fluid, which is one of the effective factors in mineralization. The highest densities of lineaments coincide in the south, west, and northwest of the region, which include dextral faults. The rose diagrams show that there are three directions in the study area. The dominant fault zone is northeastsouthwest, which include parts of the host rocks of gold mineralization. These shear zones comprise a range of ductile to brittle structures that are generally reverse and also are the longest lineaments. These faults usually displace Precambrian on Paleozoic units in southwest Saqqez, and are an indicator for subsequent localscale exploration, especially in the intersections of the EW fault systems with NWSE directions. Most of the gold mineralization in southwestern Saqqez (eg Qolqoleh, Kervian, Qabaghlojeh and Kasnazan) is related to this fault system. The second is the northwestsoutheast direction, which is parallel to the prevailing trend of Zagros fault and contains major thrust faults in the area, which cause older rocks to over thrust on younger formations. The third is the eastwest direction, which includes part of the gold mineralization and the occurrence of a brittle to ductile deformation.ConclusionThe results of this study indicate that by using semiautomatic method, faults in this area can be extracted with appropriate accuracy. Fault densities are higher in the center of the study area and in the north, west and southwest of Baneh city, and cause pass ways for hydrothermal fluids, which is one of the effective factors in mineralization. The highest densities of lineaments coincide in the south, west, and northwest of the region, which include dextral thrust, which cause older rocks to over thrust on younger formations. Three major faults were identified in the area. The fault direction and its relation to mineralization have been studied and the results show that the most dominant fault is northeastsouthwest which comprises part of the host rocks of gold mineralization. The second, northwestsoutheast direction contains thrusts and revers faults parallel to prevailing trends of Zagros fault, and the third is the eastwest direction that contains .part of the gold mineralization