بررسی محیط ژئوتکتونیکی پریدوتیت¬های منطقه آبدشت، جنوب شرق استان کرمان با استفاده از شیمی اسپینل
محورهای موضوعی :
طیبه رودباری
1
( دانشگاه تبریز )
محسن موذن
2
(دانشگاه تبریز)
سید حسام‌الدین معین زاده
3
(دانشگاه تبریز )
عبدالمجید آهنگری
4
(دانشیار گروه اقتصاد، دانشگاه شهید چمران اهواز)
کلید واژه: دونیت اسپینل سوپراسابداکشن آبدشت کرمان.,
چکیده مقاله :
پریدوتیت از عمده سنگ های تشکیل دهنده مجموعه افیولیتی آبدشت در جنوب ایران است. پریدوتیت های این مجموعه افیولیتی بیشتر از نوع دونیت و هارزبورژیت است. مهم‌ترین کانی های اولیه پریدوتیت ها الیوین، ارتوپیروکسن، اسپینل و مقدار بسیار کمی کلینوپیروکسن هستند. مطالعه شیمی اسپینل ها در این پریدوتیت ها نشان می دهد که ترکیب آنها بر اساس اعضای نهایی اسپینل بین Spl0.4 Chr0.57 Mag0.03تا Spl0.46 Chr0.51 Mag0.03 در نوسان است. عدد کروم (Cr#) اسپینل در پریدوتیت های آبدشت در حدود 73/0 تا 92/0 است و مقادیر آلومینیوم آن ها 61/3 تا 29/11 wt% است. بررسی شیمی کانی ها با استفاده از نتایج میکروپروب نشان می دهد که این کانی ها باقیمانده هایی از گوشته هستند و مقادیر بالای Cr، تهی شدگی پریدوتیت ها را نشان می دهد. بر اساس شیمی اسپینل مشخص شد که پریدوتیت های مورد مطالعه در محیط فرافرورانش (Supra-subduction) تشکیل شده اند و محدوده fore-arcبا ویژگی boninite را نشان می دهند.
Peridotites are one of the main rock types of the Abdasht ophiolitic complex in southern Iran. Peridotites of this ophiolite are dunite and harzburgite. The important original minerals in the peridotites include olivine, orthopyroxene, spinel and to the lesser amounts, clinopyroxene. Study of the chemistry of spinel in these peridotites shows that their composition, based on the end-member chemistry, is Spl0.4 Chr0.57 Mag0.03 to Spl0.46 Chr0.51 Mag0.03. The chromium number (Cr#) varies from 0.73 to 0.92 and the Al2O3 contents are3.61 to 11.29 wt%. The chemical compositions show that spinel is mantle residua phase and its high Cr content indicates the peridotites depletion. Spinel chemistry shows that the studied peridotites are related to supra-subduction environment at a fore-arc setting with boninitic features.
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