ریزرخساره‌ها، محیط‌های رسوبی و چینه‌نگاری زیستی سازند آسماری در برش دشتروم (جنوب یاسوج)

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی دکترا، گروه زمین‌شناسی، دانشکده علوم زمین، دانشگاه اصفهان، اصفهان، ایران

2 دانشجوی کارشناسی ارشد، گروه زمین‌شناسی، دانشکده علوم زمین دانشگاه شهید باهنر کرمان، کرمان، ایران

3 کارشناسی ارشد، نمایندگی سازمان زمین‌شناسی ایران در استان کهگیلویه و بویراحمد، یاسوج، ایران

چکیده

سازند آسماری توالی ستبر کربناته‌ای در حوضه فورلند زاگرس (جنوب باختر ایران) است که در زمان الیگوسن- میوسن پیشین نهشته شده است. سازند آسماری در برش دشتروم (۱۵ کیلومتری جنوب یاسوج) ستبرای 233 متر دارد. در این پژوهش ریزرخساره‌ها، محیط رسوبی و چینه‌نگاری زیستی سازند آسماری مورد بررسی قرار گرفته است. مطالعه روزن‌بران کف‌زی در این ناحیه به شناسایی 23 جنس و 32 گونه و مطالعه برش مورد نظر در مجموع به شناسایی سه مجموعه زیستی زیر انجامید:
1. Lepidocyclina-Operculina-Ditrupa assemblage zone
2. MiogypsinaElphidium sp., Peneroplis farsensis assemblage zone
3. Borelis melo curdica- Meandropsina iranica assemblage zone 
روزن‌بران شناسایی شده سن الیگوسن پیشین (روپلین- شاتین) تا میوسن پیشین (بوردیگالین) را برای سازند آسماری در منطقه مورد مطالعه پیشنهاد می‌کنند. بر پایه مطالعات آزمایشگاهی ۹ ریزرخساره آهکی در سه زیر محیط لاگون، سد و دریای باز شناسایی شد. نهشته‌های سازند آسماری در منطقه مورد مطالعه در یک سکوی کربناته دریایی اپی‌کانتیننتال از نوع رمپ هموکلینال رسوب‌گذاری کرده‌اند.
 

کلیدواژه‌ها


عنوان مقاله [English]

Microfacies, depositional environments and biostratigraphy of Asmari Formation in Dashroom section (South of Yasuj)

نویسندگان [English]

  • T. Binazadeh 1
  • A. Binazadeh 2
  • T. Vafaei 3
1 Ph.D. Student, Department of Geology, Faculty of Scince, University of Isfahan, Isfahan, Iran
2 M.Sc. Student, Department of Geology, Faculty of Scince, University of Shahid Bahonar, Kerman, Iran
3 M.Sc., The Geological Survey of Iran in Kohgiluyeh and Boyer-Ahmad Province, Yasuj, Iran
چکیده [English]

The Asmari Formation is a thick carbonate sequence in Zagros foreland basin (southwest of Iran). It was deposited during Oligocene – Early Miocene ages. The formation with a thickness of 233m cropped out in the Dashtroom section (15 km south of Yasuj). This formation was studied from microfacies, sedimentary environment and biostratigrarphy point of view. Study of benthic foraminifera led to recognition of 23 genera and 32 species. In general, three assemblage biozones were recognized in this formation, consisting of:
1. Lepidocyclina- Operculina- Ditrupa assemblage zone
2. Miogypsina Elphidium sp., Peneroplis farsensis assemblage zone
3. Borelis melo curdica- Meandropsina iranica assemblage  zone 
An age of Early Oligocene (Rupelian- Chattian)- Early Miocene (Burdigalian) is suggested for the formation at the study area. Based on laboratory studies, nine microfacies related to three subenvironments (lagoon, bar and open marine) were identified. This study revealed that, the Asmari Formation deposited on a homoclinal epicontinental carbonate ramp.

کلیدواژه‌ها [English]

  • Asmari Formation
  • Yasuj
  • Microfacies
  • OligoMiocene
  • Biostratigraphy

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