نشریه علوم زمین خوارزمی

نشریه علوم زمین خوارزمی

ماهیت و جنبش راندگی‌ها درکوهزاد پالئوژن شرق ایران: مرز خمیده شمالی پهنه‌های لوت و سیستان، منطقه سه‌چنگی

نویسندگان
شهریار کشتگر 1
محمودرضا هیهات 1
ساسان باقری 2
ابراهیم غلامی 1
سیدناصر رئیس السادات 1
1 دانشگاه بیرجند
2 دانشگاه سیستان و بلوچستان، زاهدان، ایران
10.22034/KJES.2023.8.2.104161
چکیده
رشته کوه‌های شرق ایران با ، با روند عمومی شمالی-جنوبی از گذشته به نام پهنه جوش‌خورده سیستان و اخیراً به عنوان کوهزاد پالئوژن شرق ایران معرفی شده است. منطقه سه‌چنگی در مرز خمیده شمال غربی پهنه جوش‌خورده سیستان با پهنه لوت قرار دارد. چین‌ها و راندگی­های نسل اول همراه با تورق رخ اسلیتی (چین‌های موازی) به موازات لبه شمال غربی لوت و با راستای N40E ظاهر شده­اند و شیب اغلب تراست‌ها به سمت شمال غرب است به طوری که واحدهای پرمو-تریاس درون لوت بر روی ‌سنگ‌های جوان‌تر و از جمله میکرودیوریت‌های ژوراسیک قرار گرفته‌اند. راندگی‌های نسل دوم در اثر حادثه دوم دگرشکلی یا به طور مستقیم شکل گرفته و یا راندگی­های قدیمی­تری بوده­اند که مجدداً فعال شده و چین خورده‌­اند. به طوری که اغلب دو یا چند دسته خش‌لغز در سطح این راندگی‌ها قابل تشخیص است. این نسل راندگی‌ها در راستای عمود بر لبه شمالی لوت و به موازات سطح محوری نسل دوم چین‌های بزرگ مقیاس (چین‌های شعاعی) و موازی با تورق‌های برشی منطقه با راستای N44W، مجدداً توزیع شده­اند. بنابراین جهت انتقال زمین‌ساختی در مرز شمالی لوت و سیستان از شمال غرب به جنوب شرق و از قوس خارج کوهزاد (هینترلند) به سمت داخل قوس (فورلند) است. چنین حوادث دگرشکلی پیاپی و عمود بر یکدیگر، با مدل‌های کوهزادهای برخوردی خطی ارائه شده برای شرق ایران (مدل شکستن و بازشدن پوسته قاره‌‌ای شرق ایران و برخورد خطی) همخوانی ندارد و بیشتر منطبق بر مدل خمش کوهزادی (اوروکلاین) است.
کلیدواژه‌ها
راندگی
انتقال زمین‌ساختی
خمش کوهزاد
سه‌چنگی
کوه‌های شرق ایران

عنوان مقاله English

Nature and movement of thrusts in the Paleogene orogen of eastern Iran: curved northern border of the Lut and Sistan terrains, Sechengi area

نویسندگان English

Shahriyar Keshtgar 1
Mahmoud Reza Heyhat 1
Sasan Bagheri 2
Ebrahim Gholami 1
Seyed Naser Raiisosadat 1
1 University of Birjand
2 University of Sistan and Baluchestan, Zahedan, Iran
چکیده English

The eastern Iranian ranges appearing with a NS-trending strike on the satellite images, were already known as the Sistan suture zone, but have recently been identified as the eastern Iranian orogen. The N40E first-generation folds and thrusts with slaty cleavage (parallel folds) have appeared parallel to the NE edge of the Lut block. The structural analysis shows that most of the thrusts dip to the northwest, so that the Permo-Triassic and Jurassic microdiorite units in Lut have been thrusting on the younger rocks. The structural studies show that the tectonic vergence in this deformation event is northwest to the southeast and from the outside (hinterland) to the inside (foreland) of this orogen in the Sechengi area. Younger thrusts of the second deformation event were either directly formed due to the second deformation event, or they were older thrusts that reactivated and folded, so that often two sets or more slickenlines can be recognized on the thrust plane. The recent N44W thrusts have been redistributed in perpendicular to the edge of the Lut block and parallel to the axial plane of the northwest second-generation large-scale folds (radial folds). Both the northwest folds' axial plane and penetrative shear cleavage, have dips to the northeast and southwest. These structures are parallel to the axial planes of the second-generation folds and younger thrusts. Such consecutive deformation events perpendicular to each other are inconsistent with the models of simple linear orogens presented for eastern Iran (i.e., rifting of eastern Iran continental crust and subsequent linear collision) and seem more consistent with the buckling orogens (Orocline).

کلیدواژه‌ها English

Thrust
Tectonic vergence
Orocline Buckling
Sechengi
Eastern Iranian ranges
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