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Planktonic foraminifera biozones and isotope stratigraphy of the Cenomanian-Turonian boundary in the western part of the Kopet-Dagh Basin, NE Iran
- Source :
- Journal of African Earth Sciences. 147:657-670
- Publication Year :
- 2018
- Publisher :
- Elsevier BV, 2018.
-
Abstract
- A biostratigraphic study based on the planktonic foraminifera and isotope stratigraphy of the Cenomanian-Turonian interval has been undertaken in the western part of the Kopet-Dagh Basin (NE Iran). In this research, two stratigraphic sections including: Maraveh Tappeh and Qareh Galdy have been sampled and studied. Based on planktonic foraminifera, three biozones were assigned to this interval. These are the Rotalipora cushmani Zone, Whiteinella archaeocretacea Zone and Helvetoglobotruncana helvetica Zone, These biostratigraphic data confirm a gradual faunal turnover of planktonic foraminifera, at the Cenomanian-Turonian boundary in Whiteinella archaeocretacea Zone characterized by: absences, low abundance and disappearances of complex morphotypes. After this event, in Helvetoglobotruncana helvetica Zone, along with simple globular chamber morphotypes, single keeled and double-keeled morphotypes appeared and flourished. The carbon-isotope curves in both sections, record a negative shift values below the Aitamir-Abderaz formations boundary in Whiteinella archaeocretacea Zone, and then, a positive excursion of about 5.50‰, along with several fluctuations are well evident in both sections. The δ18O values show, from the bottom to the top, a gradual increase of averagely 2‰. Based on these results, the Cenomanian-Turonian succession in this part of the Kopet-Dagh Basin is continuous and corresponds to the siltstone and chalky limestone layers of the upper part of the Aitamir Formation and the lower part of the Abderaz Formation.
- Subjects :
- 010506 paleontology
biology
δ18O
Geology
Biozone
Biostratigraphy
Structural basin
010502 geochemistry & geophysics
biology.organism_classification
01 natural sciences
Foraminifera
Paleontology
Stratigraphy
Biostratigraphy, Light isotopes, Cenomanian-Turonian boundary, Kopet-Dagh basin, NE Iran
Cenomanian
Siltstone
0105 earth and related environmental sciences
Earth-Surface Processes
Subjects
Details
- ISSN :
- 1464343X
- Volume :
- 147
- Database :
- OpenAIRE
- Journal :
- Journal of African Earth Sciences
- Accession number :
- edsair.doi.dedup.....f53139bd8a9e6614a457a2e13efa2d8c