نشریه علوم زمین خوارزمی

نشریه علوم زمین خوارزمی

بررسی تکوین ساختاری پهنه های لغزشی- فشارشی بر مبنای داده های کمی از اندازه‌گیری فراسنج های واتنش (مطالعۀ موردی: بخش شمالی زمین درز سیستان، ناحیۀ ماهیرود و توتک)

نویسندگان
ناصر احمدی کمیجانی
محمد مهدی خطیب
ابراهیم غلامی
غلامرضا میراب شبستری
محمدحسین زرین کوب
دانشگاه بیرجند، دانشکدۀ علوم، گروه زمین‌شناسی
10.52547/gnf.6.1.21
چکیده
واحدهای سنگی دگرریخته ناحیۀ توتک و ماهیرود در شمال پهنۀ زمین­درز سیستان شامل سه گروه واحد سنگی افیولیتی، آذرین و رسوبی است. در این پژوهش بر اساس مقاطع نازک و با استفاده از روش­های Rf /Ф و برش زاویه­ای تحلیل واتنش نهایی و تاوایی برروی دو مقطع انجام شد. میانگین شکل بیضیت واتنش (K) برای مقاطع شمالی و جنوبی به‌ترتیب 67/0 و 78/0 محاسبه شده است که نشان از قرارگیری در ناحیۀ واتنش پهن­شدگی بر نمودار فلین اصلاح شده و حاکی از رژیم لغزشی- فشارشی در منطقه است. مقادیر میانگین عدد جنبش شناختی تاوایی مقاطع شمالی و جنوبی به‌ترتیب 51/0 و 71/0 محاسبه شد. هم‌چنین نسبت مؤلفه برش محض و برش ساده 66 درصد به 34 درصد در مقطع شمالی و برای مقطع جنوبی هر دو مؤلفه برش محض و برش ساده 50 درصد است. این امر تأییدی بر پژوهش‌های پیشین در منطقه دارد که از میزان برش ساده با حرکت به سوی بخش شمالی زمین­درز، کاسته می­شود.

کلیدواژه‌ها
واتنش نهایی
عدد تاوایی
روش Rf /Ф
زاویه برش
زمین­درز سیستان

عنوان مقاله English

Investigation on Structural Evolution in Transperssional Zones based on Quantitative data from Measurements of Strain Parameters Case Study: Northern part of Sistan Suture zone, Tutak and Mahirud Regions

نویسندگان English

Nasser Ahmadi Comijnay
Mohammad Mahdi Khatib
Ebrahim Gholami
Gholamreza Mirab Shabestari
Mohammad Hosein Zarrinkoub
University of Birjand
چکیده English

Deformed rock units in Tutak and Mahirud regions in northern part of Sistan suture zone include ophiolite, igneous and sedimentary rocks. In this research, based on microstructures and by using Rf /Ф and shear strain methods, finite strain and vorticity analyses were carried out on both sections. The estimated values of mean strain ellipsoid shape (K-value) for both A and B sections are 0.67 and 0.78 respectively, which show flattening strain shape on the modified Flinn diagram and reveal a transpressional regime in the study area. The mean kinematic vorticity evaluated amounts for both A and B sections are 0.51 and 0.71 respectively.

Likewise, the relative contributions of the pure shear component with respect to the simple shear component are 66 to 34 percent for section A; whereas both pure and simple shear components for section B are 50 percent. These results confirm pervious study in this area which mentioned the amount of simple shear components decreased to the termination (to the north) of suture zone.

کلیدواژه‌ها English

Finite strain
Vorticity number
Rf /Ф method
Angle of shear
sistan suture zone
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