Calcareous nannofossil biostratigraphy and paleoecolgy of the Rupelian - Chattian interval in the Central Iran basin, Iran

Iranian Journal of Earth Sciences

مقالات آماده انتشار، پذیرفته شده، انتشار آنلاین از تاریخ 12 آبان 1402

نوع مقاله: Original Research Paper

شناسه دیجیتال (DOI): 10.57647/j.ijes.2024.1602.10

نویسندگان

Mohammad ShahMoradi Fahreji¹؛ Massih Afghah²؛ Marziyeh Notghi Moghaddam^{* 3}؛ Kouros Yazdjardi¹؛ Bita Mostafavi¹

¹Department of Geology, Shiraz Branch, Islamic Azad University, Shiraz,Iran

²Islamic Azad University, Shiraz Branch

³Department of Geology, Payame Noor University, Tehran, Iran

چکیده

Calcareous nannofossils have provided a powerful biostratigraphic tool since the 1950’s and 1960’s. Recent, because of the potential of nannofossil species for age determination, several authors use this fossil group in dating Cenozoic sediments and rocks. Here, we present a calcareous nannofossil biozonation for the Paleogene Period, based on biostratigraphic data from Sabzevaran section (Central Iran). Semi-quantitative counting methods applied on marine section have been used to demonstrate the details of the abundance patterns of each biostratigraphically useful calcareous nannofossil taxon. The Sabzevaran section mainly comprises of marl, limestone, and shaly limestone. Based on nannofossil assemblages three biozones were recognized in this section which is the time equivalent of NP23-NP25. According to determined biozones the age of the studied deposits in Sabzevaran section is middle Oligocene to late Oligocene age (Rupelian to Chattian stages). In this section, calcareous nannofossils abundance and diversity are medium to low with a sharp decrease slightly near the conglomerate and sandstone layers and the absence of nannofossils in conglomerate and sandstone. Based on paleoecological interpretation, the marine deposits of the Sabzevaran section were deposited in a shallow marine environment, at relatively low latitude with low productivity.

کلیدواژه‌ها

Central Iran؛ Calcareous nannofossils؛ Biostratigraphy؛ Rupelian؛ Chattian؛ Paleogene