ترموبارومتری آمفیبولیت‌های سیرجان براساس محتوای Zr در کانی اسفن(تیتانیت) و روتیل

نوع مقاله : علمی -پژوهشی

نویسندگان

دانشگاه شهید بهشتی

چکیده

بخشی از کمپلکس دگرگونی جنوب سیرجان را توده‌های آمفیبولیتی تشکیل داده‌است. این توده‌ها بصورت همیافت با گارنت مسکوویت‌ شیست‌ها و هورنبلند شیست‌ها در منطقه دیده می‌شوند. ترکیب سنگ شناسی آن‌ها شامل آمفیبول از نوع مگنزیو‌ هورنبلند تا چرماکیت، پلاژیوکلاز سدیک (Ab70)، کوارتز  و کانی‌های فرعی اپیدوت،  بیوتیت، اسفن و روتیل است. در این تحقیق با استفاده از محتوای Ti و Zr در کانی‌های اسفن و روتیل شرایط  فشار و حرارت تشکیل این سنگ‌ها مورد بررسی قرار گرفته‌است. نتایج آنالیز نقطه­ای انجام شده برروی کانی­های اسفن و روتیل در نمونه‌های انتخاب شده، بطور متوسط  Zr= 317.57 ppm, TiO2= 37.23 wt% برای کانی اسفن و Zr= 439.57 ppm, TiO2= 98.48 wt%  برای کانی روتیل است. ترموبارومتری اسفن و روتیل نشان می‌دهد که محدوده فشار- دمایی این آمفیبولیت‌ها براساس کانی اسفن T= 608-691ºC  و براساس کانی روتیل T=572-723ºC، P=7.6- 9 Kbar است. براساس این نتایج و تطابق آن‌ها با محدوده رخساره‌های مختلف دگرگونی می‌توان گفت این آمفیبولیت‌ها در طی دگرگونی ناحیه‌ای و شرایط رخساره آمفیبولیت درجه بالا تشکیل شده‌اند. AbstractPart of the metamorphic complex of south of Sirjan consist of amphibolite units. In this region, amphibolites are found with garnet muscovite schist and hornblende schist. Their lithological compositions include amphibole with magnesio-hornblende and tschermakite composition, sodic plagioclase (Ab70), epidote, quartz and biotite, with sphene and rutile as minor minerals. In this study, temperature and pressure conditions of amphibolite are evaluated by using Ti and Zr content in the rutile and sphene, minerals. The electron microprobe analysis of sphene and rutile minerals on selected samples show, the average of Zr= 317.57 ppm, TiO2= 37.23 wt% in sphene and Zr = 439.57 ppm, TiO2 = 98.48 wt% in rutile. Thermobarometry of sphene and rutile show that the range of temperature and pressure of the amphibolites based on sphene is T = 608-691ºC and based on rutile is T = 572-723ºC, P = 7.6- 9 Kbar. Based on these results and compatibility with the range of different metamorphic facieses, amphibolites were formed during regional metamorphism in high grade amphibolite facies. Keywords: Amphibolite, Thermobarometry, Sphene, Rutile, Sirjan metamorphic complex.

کلیدواژه‌ها

عنوان مقاله [English]

Thermobarometry of Sirjan’s amphibolite based on Zr content in Sphene (Titanite) and Rutile

چکیده [English]

Part of the metamorphic complex of south of Sirjan has made by amphibolite units. In this region, amphibolites are found with garnet muscovite schist and hornblende schist. Their lithological compositions include amphibole with magnesio-hornblende and tschermakite composition, sodic plagioclase (Ab70), epidote, quartz and biotite, with sphene and rutile as minor minerals. In this study, temperature and pressure conditions of amphibolite are evaluated by using Ti and Zr content in the rutile and sphene, minerals.
The electron microprobe analysis of sphene and rutile minerals on selected samples show, the average of Zr= 317.57 ppm, TiO2= 37.23 wt% in sphene and Zr = 439.57 ppm, TiO2 = 98.48 wt% in rutile. Thermobarometry of sphene and rutile based on Watson, Ferry and Tomkins calibrations show that the range of temperature and pressure of the amphibolites based on sphene is T = 608-691ºC and based on rutile is T = 572-723ºC, P = 7.6- 9 Kbar. Based on these results and compatibility with the range of different metamorphic facieses, amphibolites were formed during regional metamorphism in high grade amphibolite facies.

کلیدواژه‌ها [English]

  • Amphibolite
  • Thermobarometry
  • Sphene
  • Rutile
  • Gole Gohar metamorphic complex

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