بررسی شیمی کانی، دما-فشار سنجی و تعادل‌های فازی در سنگ‌های آتشفشانی کواترنری سبلان

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشگاه آزاد اسلامی

چکیده

سبلان عضوجوانی از مجموعه آتشفشانی سنوزوئیک، وابسته به کمان ماگمایی البرز AMA)) است. در کوه سبلان، مجموعه­ای از سنگ­های آتشفشانی با ترکیب آندزیت، آندزیت بازالتی، داسیت، ریوداسیت و تراکی آندزیت وجود دارد. بافت این سنگ­ها اغلب پورفیری با خمیره ریزسنگی، پورفیری حفره­دار و گاهی گلومروپورفیری، غربالی و تراکیتی است. کانی­های اصلی شامل پلاژیوکلاز و یک یا چند کانی مافیک چون هورنبلند و پیروکسن و کانی­های ثانویه شامل کانی کدر، ایدنگزیت، کلریت و کلسیت هستند. از شیمی
کانی­های سنگ­های منطقه برای تعیین ترکیب کانی­ها و دمافشارسنجی استفاده شد نتایج نشان داد که ترکیب بلورهای پلاژیوکلاز سنگ­های منطقه از کلسیمی تا حدواسط (An72-93) است. بر اساس نمودارهای دما-فشار سنجی پلاژیوکلازها، دما 540 تا 750 درجه سانتیگراد و فشار 5.30 تا 7 کیلوبار است که با ژرفای پوسته میانی-زیرین همخوانی دارد. دمافشارسنجی آمفیبول در سنگ­های داسیتی دمای حدود 750 درجه سانتیگراد و فشار حدود 5.5 تا 7 کیلوبار را نشان می­دهد. البته دماسنجی بیوتیت­ها در داسیت و ریوداسیت­ها دمای حدود 550 تا 650 درجه سانتیگراد را به دست می­دهد. با توجه به بررسی­های انجام شده، این سنگ­ها در یک پهنه کششی و درون قاره ای تشکیل شده­اند.
 

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of mineral chemistry, temperature–pressure measurement and mineral equilibrium in Sabalan Quaternary volcanic rocks

نویسندگان [English]

  • Abdolahadi
  • Sheikh Zakariaee
  • Mousavi
چکیده [English]

Sabalan is a young member of the Sanuzui volcanic assemblages, belonging to the Alborz Magmatic Arc (AMA(. In Sabalan mountain range, a series of volcanic rocks with a combination of andesite, basaltic andesite, rhyodacite and trachyandesite are present. The  texture of these rocks is often porphyritic with microlithic paste, porous porphyritic and sometimes glomeroporphyria, sieve and trachyte. Major minerals include clinopyroxene, plagioclase, and one or more mafic minerals such as hornblende and pyroxene. Secondary minerals include opaque minerals, iddensite, biotite, chlorite and calcite. Investigation of mineral chemistry of basaltic rocks in the region shows that the composition of calcium plagioclase crystals is moderate (An72-93(. Based on temperature–barometric diagrams of plagioclase and amphibole, a temperature of 540 to 750 oC and pressure of 5.30 to 7k have been calculated, which corresponds to the depth of the middle to lower crust. Mineralogical studies and whole rock geochemical analysis show that these rocks formed in a tensile and intercontinental zone.
 

کلیدواژه‌ها [English]

  • Sabalan
  • temperature-barometer
  • Mineral chemistry
  • Iran
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