مطالعه و بررسی کانی‌سازی توریم در کانسار آهن اکسید - آپاتیت چغارت، ناحیه‌ی معدنی بافق، منطقه‌ی ایران مرکزی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 1. گروه زمین‌شناسی، دانشکده علوم زمین، دانشگاه شهید بهشتی،تهران، ایران 2. پژوهشکده‌ی مواد و سوخت هسته‌ای، پژوهشگاه علوم و فنون هسته‌ای، سازمان انرژی اتمی ایران

2 گروه زمین‌شناسی، دانشکده علوم زمین، دانشگاه شهید بهشتی، تهران، ایران

3 پژوهشکده‌ی مواد و سوخت هسته‌ای، پژوهشگاه علوم و فنون هسته‌ای، سازمان انرژی اتمی ایران

چکیده

میزبان کانسار آهن اکسید- آپاتیت (IOA) چغارت، ریولیت‌های با سن کامبرین آغازین است. بررسی‌های پرتوسنجی و طیف‌سنجی زمینی منطقه‌ی دگرسانی در حاشیه‌ی توده‌ی ماده معدنی منیتیت- آپاتیت چغارت نشان داد که در منطقه‌ی برشی ناهنجاری‌های پرتوزایی گامای مربوط به عنصر توریم وجود دارد. تجزیه‌ی شیمیایی نمونه‌های این منطقه‌ توسط طیف‌سنجی پلاسمای جفت شده‌ی القایی)  (ICP-MS حاکی از کانی‌سازی توریم است. مطالعات کانی‌شناسی به وسیله‌ی میکروسکوپی نور عبوری و انعکاسی، ریزتجزیه‌ی ردیاب الکترونی) (EPMA نشان می‌دهد که کانی‌های اصلی توریم در این منطقه شامل توریت و اسفن هستند. مجموعه‌ی کانی‌های دگرسانی مرتبط با کانی‌سازی توریم در چغارت شامل آلبیت ± ارتوکلاز + کالک سیلیکات (اکتینولیت ـ اوژیت ـ دیوپسید) + کربنات (کلسیت) + منیتیت + پیریت ± کالکوپیریت ± گالن + اسفن+ روتیل ± میکروکلین ± آپاتیت (دگرسانی Na-Ca-Fe) تشخیص داده شد. حضور منیتیت، پیریت و کالکوپیریت پاراژنز با توریت و ناهنجاری منفی Eu در نمونه‌های منطقه‌ی کانی‌سازی توریم می‌تواند حاکی از شرایط کاهشی سیال عامل کانی‌سازی توریم باشد. الگوهای مشابه توزیع عناصر خاکی نادر بهنجار شده نسبت به کندریت و گوشته، در ریولیت‌های میزبان و منطقه‌ی کانی‌سازی توریم پیشنهاد می‌کند که منشأ توریم، ماگمای ریولیتی کمان- قاره‌ای است.

کلیدواژه‌ها


عنوان مقاله [English]

Study of Thorium Mineralization in Choghart Iron Oxide-Apatite Deposit, Bafq District, Central Iran

نویسندگان [English]

  • K Khoshnoodi 1
  • M Yazdi 2
  • M ghannadi-Maragheh 3
  • M Behzadi 2
1 1. Department of Geology, Faculty of Earth Science, Shahid Beheshti University 2. Materials and Nuclear Fuel Research School, Nuclear Science and Technology Research Institute, AEOI
2 Department of Geology, Faculty of Earth Science, Shahid Beheshti University
3 Materials and Nuclear Fuel Research School, Nuclear Science and Technology Research Institute, AEOI
چکیده [English]

Early Cambrian rhyolite hosts the Choghart iron oxide-apatite (IOA) deposit. The ground radiometric and spectrometric surveys of alteration zone on the margin of the magnetite-apatite ore body show that the radioactive anomaly of thorium occurs in the breccia zone. The chemical analyses of the breccia zone samples by ICP–MS show thorium mineralization. The mineralogical studies by transmitted- and reflected-light microscopey and EPMA indicate that the main thorium minerals in thorium mineralization zone are thorite and sphene. The alteration mineral assemblages related to thorium mineralization of Choghart is consisted of albite ± orthoclase + calc-silicate (actinolite- augite- diopside) + carbonate (calcite) + magnetite + pyrite ± chalcopyrite ± galena + sphene + rutile ± microcline ± apatite (Na-Ca-Fe alteration). The occurrence of paragentic magnetite, pyrite and chalcopyrite with thorite and negative Eu anomaly in the thorium mineralization zone indicate a reduced condition for thorium mineralizing fluids. The similarity in chondrite- and mantle-normalized REE patterns of host rhyolite and the thorium mineralization zone suggests that thorium is originated from continental-arc rhyolitic magma.

کلیدواژه‌ها [English]

  • Thorium Mineralization
  • Iron Oxide-Apatite Deposit
  • Chogart
  • Bafq District

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