کاربرد آنالیز عنصری در تعیین مدل دولومیتی شدن سازندهای سورمق و آباده در برش همبست، ناحیه آباده، ایران

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه زمین شناسی، دانشکده علوم پایه، دانشگاه لرستان، خرم آباد

چکیده

منطقه مورد مطالعه در 60 کیلومتری جنوب شرق شهر آباده و در بخش شمال شرقی کوه همبست قرار دارد که رخنمونهای کاملی از پرمین میانی تا پرمین بالایی را شامل می شود و دارای دو مقطع چینه شناسی در دره همبست می باشد. بر پایه شواهد صحرایی، سنگ نگاری و ژئوشیمیایی بر مبنای آنالیز عنصری به روش های (EDS)و (EPMA)، دو گروه اصلی از دولومیت ها شناسایی شد که شامل دولومیت های اولیه و دولومیت های ثانویه می باشند. دولومیت های اولیه شامل دلومیکرایت ها با بافت موزائیکی و اغلب آنهدرال و دولومیت های ثانویه شامل دولومیکرواسپارایت ها بصورت ساب هدرال و دولواسپارایت ها اغلب سابهدرال و یوهدرال می باشند.در دلومیکرایت ها کاهش Mg نسبت به دیگر دلومیت ها به دلیل بالا بودن مقدار Ca می باشد. به طور کلی مقدار Sr در دولومیت های موردمطالعه از دلومیکرایت به سمت دولواسپارایت کاهش را نشان می دهد و افزایش استرانسیم در دلومیکرایت به دلیل عملکرد فرایندهای دیاژنزی روی پوسته های آراگونیتی است.

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