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ثبت فرامینیفرهای پلانکتون مرز سنومانین/تورونین در حوضه کپه داغ (شمال شرق ایران) | ||
پژوهش های چینه نگاری و رسوب شناسی | ||
مقالات آماده انتشار، پذیرفته شده، انتشار آنلاین از تاریخ 10 آبان 1402 | ||
نوع مقاله: مقاله پژوهشی انگلیسی | ||
شناسه دیجیتال (DOI): 10.22108/jssr.2023.138780.1265 | ||
نویسندگان | ||
بهناز کلنات* 1؛ محمد حسین محمودی قرایی2 | ||
1گروه دیرینه شناسی گیاهی، مؤسسه تحقیقات جنگل ها و مراتع کشور، سازمان تحقیقات آموزش و ترویج کشاورزی، تهران، ایران | ||
2گروه زمین شناسی، دانشکده علوم، دانشگاه فردوسی مشهد، مشهد، ایران | ||
چکیده | ||
The shale-marlstone interval of the upper Aitamir-lower Abderaz formations in the southeastern part of the Kopet-Dagh Basin investigated using planktonic foraminiferal studies to determine how surface and water column characteristics of the basin were influenced by Cenomanian/Turonian boundary conditions. Three planktonic foraminiferal biozones (upper part of the Rotlipora cushmani Total Range Zone, Whiteinella archaeocretacea Interval Zone, and lower part of the Helvetoglobotruncana helvetica Total Range Zone) have been identified in the studied section, which suggests a late Cenomanian–early Turonian age for this interval. The Aitamir-Abderaz boundary is supposed to be comformable in this section because of the presence of all the C/T boundary planktonic foraminiferal biozones and no evidence of subaerial exposure in the field. The presence of benthic foraminifera throughout the studied section indicate that the OAE2 interval in this succession have never experienced a completely oxygen-depletion at the bottom water. However, low diversity of planktonic foraminifera and low abundance of specialized species indicate more stressful conditions due to intensified weathering and higher productivity (eutrophic conditions) during the OAE2 interval. This interval is punctuated by a transient period with higher diversity of planktonic foraminifera and more abundance of specialized species at the upper part of R. cushmani biozone-lower part of W. archaeocretacea biozone. This interval can be corresponded to “Plenus Cold Event” and demonstrate more stable and oligotrophic conditions across the OAE2. | ||
کلیدواژهها | ||
Palaeoecology؛ OAE2؛ Plankonic foraminifera؛ biostratigraphy | ||
آمار تعداد مشاهده مقاله: 35 |