بررسی سازوکار جایگزینی همبافت گرانیتوئیدی بروجرد با استفاده از روش ناهمسانگردی قابلیت مغناطیس شدگی

نویسندگان

1 دانشگاه تهران

2 دانشگاه تربیت مدرس تهران

چکیده

همبافت گرانیتوئیدی بروجرد یکی از همبات­های نفوذی بزرگ در پهنه­ی ساختاری سنندج- سیرجان است که واحد سنگ‌شناسی غالب آن گرانودیوریتی است و استوک­های کوچک کوارتزدیوریتی و مونزوگرانیتی نیز آن را همراهی می­کنند.  بررسی سازوکار جایگزینی همبات­ گرانیتوئیدی بروجرد (غرب ایران) با استفاده از روش ناهمسانگردی پذیررفتاری مغناطیسی (AMS) بر پایه­ی نتایج حاصل از آنالیز 290 نمونه تهیه شده از 96 ایستگاه از واحدهای سنگ­شناختی اصلی همبافت انجام شده است. نتایج حاصل نشان می­دهدکه همبافت یاد شده، جزء گرانیتوئیدهای پارامغناطیس بوده و میزان پذیرفتاری و مغناطیسی ناهمسانگرد مغناطیسی از واحد کوارتزدیوریتی به واحد مونزوگرانیتی کاهش می­یابد. همچنین شکل بیضوی مغناطیسی در نصف ایستگاه­ها، خطی و در بقیه ایستگاه­ها صفحه­ایست. بافت­های مغناطیسی نشاندهنده این است که جایگزینی همبات­ گرانیتوئیدی بروجرد به صورت سیل انجام شده است و خاستگاه ساختاری همبات­ گرانیتوئیدی بروجرد، فضاهای کششی محصول رژیم زمین­ساختی ترافشارشی هستند.

کلیدواژه‌ها


عنوان مقاله [English]

Study of Broujerd granitic complex replacement mechanism with use of, the anisotropy of magnetic susceptibility method

چکیده [English]

Broujerd granitoid complex is one of the large intrusive complexes in structural zone of Sanandaj-Sirjan and petrologicaly they are composed of granodiorite and quartzdiorite and which are accompanied by monzogranite stocks. Study of Broujerd granitoid complex replacement mechanism (west of Iran) has been done with the use of anisotropic magnetic susceptibility technique (AMS) on the basis of results obtained from analysis of 290 samples collected from 96 stations from the main petrologic units. The results show that this complex is part of paramagnetic granitoids and rate of magnetic susceptibility anisotropy is reduced from quartz diorite to monzogranite unit. Elliptical magnetic form is in half of the linear stations and in rest of plane stations. Magnetic fabrics show that replacement of Broujerd granitic complex has been done as sill and structural setting of granitic complex in Broujerd is extensional-shear fractures which are product of transpression tectonic regime.  

کلیدواژه‌ها [English]

  • Broujerd Granitic complex
  • anisotropy of magnetic susceptibility
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