بررسی سنگ شناسی، کانی شناسی و سنگ زایی پریدوتیت های سوره دال در جنوب ماشکان-شمال غرب ایران

نویسندگان

دانشگاه تبریز

چکیده

منطقه­ی مورد بررسی در کوه‌های سوره‌دال، جنوب روستای ماشکان، در مرز ایران با عراق واقع شده‌‌است. سنگ­های اولترامافیک در این منطقه با ترکیب هارزبورژیت تا دونیت با درجات متفاوت سرپانتینی شده­­اند. بر اساس بررسی­های ‌شیمی کانی­ها، ترکیب الیوین‌ به طور اصلی فورستریت (Fo 85.07- 91.55) و ترکیب ارتوپیروکسن عمدتاً  انستاتیت (En 0.89- 0.92) است. ترکیب کلینوپیروکسن‌ دیوپسیدی است  و مقادیر Al/(Al+Fe3++Cr) بین 02/0-57/0 در تغییر است. ترکیب اعضای نهایی اسپینل‌ها، Mag (0.04- 0.06) ،Chr (0.62-0.66) و Spl (0.51-0.58) است. عدد منیزیم اسپینل بین 52/0- 62/0 و عدد کروم در حدود 59/0-69/0 است. با استفاده از نتایج تجزیه ریزپردازشی کانی­ها، محیط اقیانوسی برای این نوع پریدوتیت‌ها تعیین شده‌است. این پریدوتیت‌ها در منطقه­ی چند فرورانشی (SSZ) در جلوی قوس (Forearc) تشکیل شده‌اند.  بر این اساس افیولیت­های سوره دال در انتهایی­ترین بخش شمال­غربی زون زاگرس بقایایی از سنگ کره اقیانوسی شاخه جنوبی Neo-Tethyan تشکیل می­دهند. که در اصل بین حاشیه­های قاره­ای عربستان (به سمت جنوب) و اوراسیا (به سمت شمال) در طی اواخر کرتاسه تشکیل شده‌اند و همسانی بسیار نزدیکی با افیولیت­های کرمانشاه و عراق در کمربند افیولیتی زاگرس را نشان می­دهند.

کلیدواژه‌ها


عنوان مقاله [English]

Petrology, mineralogy and petrogenesis of the Soredal peridotites from southern Mashkan-NW Iran

چکیده [English]

The study area is located in the Soredal mountains, southern Mashkan village in the border of Iran with Iraq. The rock compositions are harzburgite to dunite which metamorphosed under various degrees of serpentinization. On the basis of mineral chemistry studies, main compositions of olivine and orthopyroxene are Fo (85.07- 91.55) and En (0.89- 0.92) respectively. Composition of clinopyroxene is diopside and Al/(Al+Fe3++Cr) ratio is between 0.02 and 0.57. Spinel end- member composition is as Mag (0.04- 0.06), Chr (0.62- 0.66) and Spl (0.51- 0.58). Mg number of spinel is varied between 0.52- 0.62 and Cr number is about 0.59- 0.69. The mineral chemistry studies indicate an oceanic property of the Soredal peridotites. The rocks are formed in forearc supra-subduction zone (SSZ) setting. The investigated rocks in the  the end part of north western Zagros ophiolitic belt are remnants of oceanic lithosphere of southern branch of Neo-Tethyan which are formed during late Cretaceous between Arabian (toward south) and Eurasia (toward north) continental margins. They are very similar to Kermanshah and Iraq ophiolites in the ophiolitic Zagros belt.

کلیدواژه‌ها [English]

  • Mineral chemistry
  • peridotite
  • Soredal
  • Mashkan
  • NW Iran
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