زمین‌شیمی، سنگ‌اولیه و موقعیت زمین‌ساختی سرپانتینیت‌های مجموعه افیولیتی نی‌ریز در جنوب بوانات (استان فارس)

نویسندگان

1 دانشجوی دکترا، گروه زمین‌شناسی، دانشکده علوم‌پایه، دانشگاه لرستان، خرم‌آباد، ایران

2 دانشیار گروه زمین‌شناسی، دانشکده علوم‌پایه، دانشگاه لرستان، خرم‌آباد، ایران

3 استادیار گروه زمین‌شناسی، واحد شیراز، دانشگاه آزاد اسلامی، شیراز، ایران

چکیده

منطقه جنوب بوانات در پهنه زاگرس مرتفع قرار دارد و جزئی از افیولیت نیریز محسوب می‌شود. در این منطقه، مجموعه افیولیتی به صورت آمیزه رنگین کوچک شامل چرت‌های رادیولاریتی و سرپانتینیت‌ها می‌باشد. سرپانتینیت‌ها حاوی سرپانتین، اسپینل، کانی‌های تیره (به عنوان کانی‌های باقیمانده از سنگ‌اولیه)، آمفیبول و به ندرت الیوین و پیروکسن هستند. الیوین‌ها به شدت به سرپانتین و پیروکسن‌ها به بستایت تبدیل شده‌اند. مقادیر پایین Al2O3 و خیلی پایین TiO2 در مقابل مقادیر بالای MgO، Cr، Ni و V در این سرپانتینیت‌ها، بیانگر سنگ‌اولیه هارزبورژیت - دونیت گوشته‌ای برای آن­هاست. مقادیر خیلی پایین CaO در این سنگ‌ها نیز نشان دهنده میزان کم کلینوپیروکسن در سنگ‌اولیه و نوع هارزبورژیتی - دونیتی آن است. براساس شیمی عناصر اصلی، کمیاب و فرعی، پریدوتیت‌های اولیه تشکیل‌دهنده این سنگ‌ها در یک محیط فرافرورانش - جلوقوس از یک گوشته‌ی متأثر از واکنش با مذاب (واکنش مذاب – سنگ) حاصل از صفحه فرورونده، تشکیل شده‌اند.

کلیدواژه‌ها


عنوان مقاله [English]

Geochemistry, protolith and tectonic setting of serpentinites from the Neyriz ophiolitic complex in the south of Bavanat (Fars Province)

نویسندگان [English]

  • M. Zurmand Sangari 1
  • A. Ahmadi khalaji 2
  • K. Noori Khankahdani 3
  • Z. Tahmasbi 2
1 Ph. D. student, Dept. of Geology, Faculty of sciences, Lorestan University, Khoramabad, Iran
2 Assoc. Prof., Dept. of Geology, Faculty of sciences, Lorestan University, Khoramabad, Iran
3 Assist. Prof., Dept. of Geology, Shiraz Branch, Islamic Azad University, Shiraz, Iran
چکیده [English]

The south of Bavanat area is located in the high Zagros zone and it is considered a part of the Neyriz ophiolite. In this area, the ophiolitic complex is small coloured melanges include radiolarite cherts and serpentinites. The serpentinites composed of serpentine, spinel, opaque (as residual minerals from protholith), amphibole, rarely olivine and pyroxene. Olivines have been highly altered to serpentine and pyroxenes to bastite. Low values of Al2O3 and very low TiO2 against high values MgO, Cr, Ni and V in these serpentinites indicate the protholith of harzburgite- dunite tectonites. Also, very low values of CaO in these serpentinites indicate the low amount of clinopyroxene in the protholith and its harzburgite-dunite type. Based on the chemistry of the major, minor and rare elements, the primary peridotites that make up these rocks are formed in the suprasubduction-fore arc zone from a mantle affected by the reaction with the melt (melt-rock reaction) resulting from the subducted plate.

کلیدواژه‌ها [English]

  • High Zagros
  • Bavanat
  • Ophiolite
  • Serpentinite
  • Suprasubduction (SSZ)
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