مطالعه رفتار مکانیکی سنگ‌کره در منطقه زاگرس با استفاده از مدل‌سازی عددی سه‌بعدی مکانیکی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 سازمان نقشه‌برداری کشور، اداره ژئودزی و ژئودینامیک، تهران، ایران

2 دانشگاه صنعتی خواجه نصیرالدین طوسی،گروه مهندسی ژئودزی و ژئوماتیک، تهران، ایران

3 مرکز تحصیلات تکمیلی در علوم پایه زنجان،گروه فیزیک، زنجان، ایران

4 پژوهشگاه بین المللی زلزله‌شناسی و مهندسی زلزله، تهران، ایران

5 سازمان زمین‌شناسی واکتشافات معدنی کشور، پژوهشکده علوم‌زمین، تهران، ایران

چکیده

مطالعه رفتار  سنگ‌کره(سنگ‌کره) به عنوان یک لایه مکانیکی قوی که شامل پوسته و گوشته بالایی است از جمله مباحث روز علوم ژئودینامیک است. در این مقاله با استفاده از مدل‌سازی عددی سه بعدی به روش المان محدود و استفاده از یک ریولوژی ویسکوز وابسته به دما (خزشی) در دو حالت مرطوب و خشک رفتار مکانیکی سنگ‌کره در زاگرس با استفاده از دو ژئوترم گرم و سرد مورد بررسی قرار می‌گیرد. ستبرای پوسته بالا و پایین و همچنین قسمت گوشته بالایی بر اساس نگاشت‌های زلزله‌شناسی ( (Yaminifar, 2007; Paul, 2006;  Hatezfeld, 2003 در مناطق مختلف زاگرس در نظرگرفته شده است. گسل‌ها به صورت المان‌های ویژه در مدل جاسازی شدند و از قانون کولمب پیروی می‌کند. نتایج نشان می‌دهد که مرز تغییر شکل (BDT)  برای ژئوترم سرد و ریولوژی مرطوب در ژرفای 10.5کیلومتری و برای ژئوترم سرد و ریولوژی خشک در ژرفای 14کیلومتری رخ می‌دهد. همچنین این مرز تغییر شکل(BDT) برای ژئوترم گرم به ترتیب در ژرفای  8 و 11 کیلومتری رخ می‌دهد. این نتایج تطابق خوبی با ژرفای زمین‌لرزه‌هایی که در منطقه زاگرس رخ می‌دهد (Tatar, 2004; Jackson, 2008)  دارد و گویای  استحکام  سنگ‌کره در قسمت پوسته متمرکز است.
 

کلیدواژه‌ها


عنوان مقاله [English]

Preliminary Results of Long Term Strength of Lithosphere in the Zagros Mountains of Iran: Insight from Mechanical Modeling

نویسندگان [English]

  • H. R. Nankali 1
  • B. Vosoughi 2
  • F. Soboutie 3
  • K. Hessami 4
  • M. Talebian 5
1 National Cartographic Center of Iran, Geodesy and Geodynamics Department Tehran, Iran
2 Khajeh Nasridin Toosi, University of Technology, Faculty of Geodesy and Geomatics Engineering, Tehran, Iran
3 Institute for Advanced Studies in Basic Sciences, Department of physics, Zanjan, Iran
4 International Institute of earthquake of Engineering and Seismology, Tehran, Iran
5 Research Institute for Earth Science, Geological Survey of Iran, Tehran, Iran
چکیده [English]

A three-dimensional lithosphere model with horizontal dimensions of 1500 km×600 km and a depth extent of 70 km for the Zagros is constructed from available geophysical data to find out strength of the outermost layers in this area. The structural boundaries of the model are based on the results from the deep seismic sounding profiles. First the finite element model for the temperature is solved in order to obtain initial temperature and the geotherm, after that structural viscoelastic problem is solved using the same mesh as in the thermal initial condition. Preliminary results for wet and dry rheology indicate that the depth of the BDT is about 8 km and 11 km for hot geotherm and 10.5 km to14 km for cold geotherm. The results are in good agreement with focal depth in the Zagros that most earthquakes occur in 8 to 15 km depth (Tatar et al., 2004 and Jackson et al., 2008), that the long-term strength of the continental lithosphere resided only in its upper part, which was contained wholly within the crust.

کلیدواژه‌ها [English]

  • Rheology
  • Finite-Element Methods
  • Brittle
  • Geotherm
  • Iran
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