ویژگی های کانی شناختی و ژئوشیمیایی توده گرانیتوئیدی کوه سورمه، شمال باختر نهبندان؛ خاور بلوک لوت

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه زمین‌شناسی، دانشکده علوم پایه، دانشگاه سیستان و بلوچستان

چکیده

گرانیتوئید کوه سورمه در جنوب­خاوری استان خراسان جنوبی و 50 کیلومتری شمال باختری شهرستان نهبندان قرار دارد. از لحاظ تقسیمات زمین­شناسی ایران این توده در محل اتصال بخش خاوری پهنه لوت و زون زمین­درز سیستان واقع شده است. این توده­ از تعدادی توده کوچک به صورت استوک مانند و منقطع با روند عمومی شمال­باختری-جنوب­خاوری در داخل مجموعه­های فلیشی منتسب به سازند شمشک؟ برونزد دارد؛ پیکره اصلی آن ترکیب دیوریتی و گرانودیوریتی دارد. پلاژیوکلاز، کوارتز، آلکالی­فلدسپار، هورنبلند و بیوتیت مهم­ترین کانی­های سازنده­ی توده­ها می­باشند. گرانیتوئید کوه سورمه کالکوآلکالن، متاآلومینوس تا پرآلومینوس و دارای خاستگاه آذرین (I) است.  شواهدی چون حضور هورنبلند، بیوتیت و نبود موسکوویت و داده‌های ژئوشیمیایی این گرانیتوئید نشان از خاستگاه آذرین این توده دارد. این توده­ها دارای غنی­شدگی از عناصر نادر خاکی سبک (LREE) و فقیر شدگی از عناصر نادر خاکی سنگین (HREE) با الگوی مشابه می­باشند، این اختصاصات به احتمال بیانگر منشاء مشترک آن­ها است. نمودارهای جداکننده­ی محیط­های زمین­ساختی جایگاه گرانیتوئیدهای کوه سورمه را وابسته به کمان­های آتشفشانی حاشیه قاره معلوم می­دارد. تغییرات نـسبت­های Th/Yb و Ta/Yb نـشان می­دهد که ماگمای سازنده واحدهای گرانیتوئیدی متعلق به زون­های فرورانشی غنی شده می­باشند.

کلیدواژه‌ها


عنوان مقاله [English]

Mineralogy and geochemistry properties of Surma granitoids, Northeast Nehbandan, East of Lut block

نویسندگان [English]

  • Habib Biabangard
  • Jamila tayabi
چکیده [English]

Abstract: Surme granitoid plutons are located southeast of Southeastern Khorasan province and 50Km in Northwestern of Nehbandan city. Basd on geological of Iran classification this pluton is located at the junction of the eastern part of Lut and Sistan suture zone. The mass is composed of a small mass number such as stocks with the general trend northwest - southeast that interrupted flysch series and outcroup to Shemshak formation? Main body of pluton is Diorite and granodiorite composition. Plagioclase, quartz, alkali feldspar, hornblende and biotite are the main minerals component of this pluton. Surme granitoid is Calc- alkaline, metaluminous to peraluminous and I type. Depletion of Nb, P, Yb,Y and Ti elements suggest that the parent magmas relate to the subduction zone setting and affected by crustal contamination.These plutons have enriched in light rare earth elements (LREE) and depleted in heavy rare earth elements (HREE) with similar patterns.These characteristics indicate the likely origin of magma that originated from the subducted oceanic crust and metasomatisem with wedge mantle and finally contamination with crustal material. According to the tectonic discrimination diagrams surme granitoid has related to the active continental crust. Surme granitoid have low Sr (135- 205ppm), Sr/Y and plot predominantly in the field of mantle- derived arc magmas (normal Calc- alkaline rocks). Variations in Th/Yb and Ta/Yb ratios indicate that the resulted magma of granitoids unites have been affected by crustal contamination en route to the surface.

کلیدواژه‌ها [English]

  • Continental margin
  • Surme granitoid
  • Nehbandan
  • Lut block
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