Writers : Hashemirastegar,Kosar ;Supervisor:B,Hemadi
Refference : M.Sc.Thesis - Research Institute for Earth Sciences, Tehran
Publishing Year : 1384

Abstract :

The cutting of the west of Mohammad a bad is selected and prepared for a litho- biostratiography study along with upper paleecology sediments this cutting was consisted of Tuff, Andesit tuff with the green to gray color and in the upper part ends to thin to medium thickness limestone.
Micritons layers are settled on volcanic parts with nonconformity and then light micritous layers, sandstone layers and limestone layers are appeared on them In total 12 rock units have been defined in the study area.
In this study, 112 samples of limestone have collected and prepared for microstratigraphy study and in biostratigraphy studies in Mohamadabad section, 4 biozones have been recognized.
1- Dicarinell concavata - Marginotruncana Assemblage zone.
2- Globotruncanita calcarata- Globotruncanita elevate Assemblage zone.
3- Globotruncanita, elevata - Globotruncanita fasostuarti Interval zone.
4- Globotruncanita - Rosita contuse Biozone.
in relation to micropaleontology, 24 types of foraminifers in 9Genus and 3 species of nonforaminifers of 2 Genus, oligosteginidae and Minoxia, have been in troduced.
The real thickness of the related cutting sample was about 700 meters It s was assessed based 011 the Assemlage zone society especially planktonic foraminifers, Santinian to Maestrishtian.
In this area, because of' the sub 1-Jercynian phase performance and because
of the lack of the related fossiles and because of nonconformity base the lack of Turonian and coniasian stages have been observed in such a case that in other parts of the area there wasn't any sediment related to these stages Based of paleoecology, the saltiness of the environment is because of the accumulation of different foraminifers with regular species and also because of the prevelance of planktonic foraminifers in relation to benthic foraminifers In relation to studies about micro facises in the related culling west part of Mohammadabad 8 micro facises have been defined and separatedas follows:
1- Micrit (Mudstone)
2- Biomicrite (Bioclastic Mudstone to wackestone
3- Biomicrite (Radiolarian wackestone)
4- Biomicrite (Oligosteginid wackestone)
5- Biomicrite (Globotruncanid wackestone)
6- Biosparite (Bioclastic packstone)
7- Tuff sandstone
8- Sandstone (Lithic Arcoze)
Based on these microfacies the deep and half deep seainvironment sedimentation is shown the shape of the culting sample and rich fossilous society rich of planktionic foraminifers shows a quiet and ratonally deep site for production of these sediments. And crowded planktonic foraminifers shows the relation ship of this area with open seas is santonian-Maestritiotian alignment.

Subject List : Biostratigraphy, Lithostratigraphy