Writers : Babazadeh, S.A.; Raisossadat, S.N.; Ahrari, F.
Publishing Year : 1389

Abstract :

South west of Qayen area is one of the platform basins in the Thethys, which contains microfossils such as orbitolinids. Six species belonging to the genera Praeorbitolina, Palorbitolina, Palorbitolinoides, Mesorbitolina, and Conicorbitolina were identified in Qomenjan area. Based on orbitolinids species, two biozones including Mesorbitolina texana and Palorbitolina lenticularis are suggested. The age of sediments is attributed to Late Baremian -Early Cenomanian and Early Aptian-Early Cenomanian. Based on occurrence and stratigraphic distributions of orbitolinids in the Qomenjan section and comparison with Cherchi and Schroeder s evolutionary model, Praeorbitolina cormyi-Conicorbitolina cuvilleri and Palorbitolina lenticularis- Conicorbitolina cuvilleri phylogenetic lineage is suggested for the Qomenjan area herein. The most important changes in the phylogenetic lineage, represented in our research, are as follows: the change in the position of embryonic apparatus, the shape of the protoconch and subembryonic zone, increase in the size of embryonic apparatus and protoconch, increase in the number of subembryonic and deuteroconch partition.

Subject List : biostratigraphy