سنگ‌نگاری، ژئوشیمی و ترکیب ایزوتوپی Sr-Nd متابازیت‌های مجموعة دگرگونی بنه‌ شورو، شرق ساغند، ایران مرکزی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی دکترا، گروه زمین‌شناسی، دانشگاه تربیت مدرس، تهران، ایران

2 دانشیار، گروه زمین‌شناسی، دانشگاه تربیت مدرس، تهران، ایران

3 دکترا، سازمان زمین‌شناسی و اکتشافات معدنی کشور، تهران، ایران

چکیده

مجموعة دگرگونی بنه‌شورو در شرق روستای ساغند و در حوزة ایران مرکزی واقع شده‌است. این مجموعه از گنایس‏های کوارتز-فلدسپاتیک (کانی تیرة کمتر از 5 درصد)، بیوتیت -آمفیبول گنایس‌ ، واحدهای متابازیت، انواع شیست با میان ‏لایه‏هایی از مرمر و کوارتزیت و نفوذ‏ی‏های مافیک و اسیدی تشکیل شده که مجموعاً دگرگونی قهقرایی در حد رخسارة آمفیبولیت پایینی را متحمل شده‏اند. مطالعة ژئوشیمیایی متابازیت‌های این مجموعه در کوه‌‌ زمان‌آباد و پشتة گلمنده، بیانگر وجود دو الگوی توزیع غنی شدة متفاوت در نمودارهای به هنجار شدة عناصر فرعی و کمیاب این سنگ‌ها نسبت به MORB می‌باشد. الگوی اول فاقد و الگوی دوم دارای آنومالی منفی در Nb و Taاست. مطالعة ژئوشیمی سنگ کل به همراه نسبت‌های ایزوتوپیSr-Nd، بیانگر دخالت دو منشأ گوشته‌ای متفاوت در تشکیل ماگمای مادر متابازیت‌ها در یک محیط پشت قوسی است. منبع گوشته‌ای غنی از تیتانیوم، مانند دنبالة پلوم‌های گوشته‌ای در تشکیل نمونه‌های غنی از Ta و Nb وگوشتة غنی شدة قدیمی متأثر از فرورانش در تشکیل نمونه‌های تهی‌شده از Ta و Nb نقش دارد.

کلیدواژه‌ها


عنوان مقاله [English]

Petrology, geochemistry and Sr-Nd isotopic composition of the metabasic rocks of Boneh shurow metamorphic complex, East of Saghand, Central Iran

نویسندگان [English]

  • Leila Maleki 1
  • Nematollah Rashidnejad Omran 2
  • Abdolrahim Houshmandzadeh 3
1 Ph.D. Student, Department of Geology, Tarbiat Modares University, Tehran, Iran
2 Associate Professor, Department of Geology, Tarbiat Modares University, Tehran, Iran
3 Ph.D., Geological Survey of Iran (GSI), Tehran, Iran
چکیده [English]

Boneh shurow metamorphic complex is located in the east of Saghand area, Central Iran. This complex consists of quartz-feldspatic gneiss (mafic minerals < 5%), biotite-amphibole gneisses, metabasics rocks, schists, subordinate dolomitic marble and quartzite interlayers and mafic and felsic magmatic intrusions that they have been retrogressed to lower amphibolite facies. In MORB-normalized plots, the metabasic samples can be classified into two groups: first group does not display Nb-Ta anomaly and second group displays negative Nb-Ta anomaly. Whole rock geochemistry and Sr– Nd isotopic composition of metabasic unites suggest derivation from two different mantlic sources in the back arc setting. A source enriched in Ti, such as plume tail, and an old enriched mantle that has been affected by subduction, can be involved in generation of the first and second group, respectively

کلیدواژه‌ها [English]

  • Central Iran
  • Saghand
  • Boneh shurow
  • Metamorphism
  • Metabasic
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