تحلیل جنبش شناختی بودین‌های نامتقارن گستره دورود، غرب پهنه سنندج-سیرجان
محورهای موضوعی :
1 - زمین‌شناسی (تکتونیک)، گروه زمین‌شناسی، دانشکده علوم پایه، دانشگاه لرستان
کلید واژه: برش عمومي, بودين, تاوايي, جريان ترافشارشي, كمربند كوهزايي زاگرس,
چکیده مقاله :
داده‌های ساختاری از بودین‌های نامتقارن و سنگهای گرنیت- میلونیتی در ناحیه دورود، شاخص‌های خوبی برای تخمین کمی واتنش نهایی، عدد تاوایی (Wk) و در نهایت تحلیل جنبش شناختی الگوی دگرشکلی گستره مورد مطالعه می‌باشند. این گستره بخشی از پهنه سنندج - سیرجان است و در کمربند کوهزایی زاگرس واقع شده است. انواع بودین‌های نامتقارن دومینو و نوار برشی در لایه‌های کوارتزیتی دگرشکل شده مرتبط با گرانیت میلونیت، میکا شیست و سنگ‌آهک ایجاد شدهاند. بودین‌های نوار برشی با چرخش به عقب و بودین‌های دومینو با چرخش رو به جلو، هر دو جهت برشی راست‌گرد را نشان می‌دهند. پورفیروکلاستهای غلافی موجود در گرانیت- میلونیتها نیز جهت برشی راست‌گرد را تایید میکنند. عدد تاوایی جنبش شناختی (Wm) با استفاده از روشهای توزیع هذلولی بودین نامتقارن و الگوهای فابریک محور c کوارتز برآورد شدند. Wm محاسبه شده از روشهای توزیع هذلولی بودین نامتقارن و الگوهای فابریک محور c کوارتز، ترکیبی از 30 درصد تا 48 درصد مولفه برش ساده و 52 درصد تا 70 درصد مولفه برش محض را نشان می‌دهند. نتایج به‌دست‌آمده نشان می‌دهند بودین های نامتقارن روش مناسبی برای تخمین عدد تاوایی می‌باشند. این تحلیل‌های کمی نشان‌دهنده دگرشکلی برشی عمومی توسعه‌یافته در امتداد کمربند دگرگونی سنندج- سیرجان است که در رژیم جریان ترافشارشی همراه با کوتاه شدگی عمود بر مرز ناحیه برشی به وجود آمده است.
Structural data from asymmetric folds and granite-mylonite rocks in the Doroud region provide good indicators for quantitatively estimating the final strain, the tau number (Wk), and, ultimately, the kinematic analysis of the deformation pattern in the studied area. This region is part of the Sanandaj-Sirjan zone, located within the Zagros orogenic belt. Types of asymmetric domino and shear-band boudins in quartzite layers, which are deformed and associated with granite-mylonite, mica schist, and limestone, have been identified. Shear-band boudins exhibit a backward rotation, while domino folds exhibit a forward rotation, both showing a dextral shear direction. Mantled porphyroclasts found in the granite-mylonites also confirm the dextral shear direction. The mean kinematic vorticity number (Wm) was estimated using the methods of asymmetric boudin hyperbolic distribution and quartz c-axis pattern. The Wm calculated from these methods shows a combination of 30% to 48% simple shear component and 52% to 70% pure shear component. The results suggest that asymmetric boudins are an appropriate method for estimating the kinematic vorticity number. These quantitative analyses reflect the general shear deformation developed along the Sanandaj-Sirjan metamorphic belt, which has formed in a transpressional flow regime with shortening perpendicular to the shear zone boundary.
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