Microbiostratigraphy of Asmari formation at Derak section (Shiraz)

Subject Areas :

KHosro KHosro-Tehrani ¹ , فریده Keshani ² , مسیح Afgheh ³ , معصومه Ahmadi ⁴

1 - استاد گروه زمین شناسی، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات تهران
2 - استادیار گروه زمین شناسی، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات تهران
3 - استادیار گروه زمین شناسی، دانشگاه آزاد اسلامی، واحد شیراز
4 - دانش آموخته کارشناسی ارشد، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات تهران

Received: 2016-09-07 Accepted : 2016-09-07 Published : 2011-12-22

Keywords: Asmari Formation, benthic foraminifera, Biostratigraphy, Derak montion,

Abstract :

This study concentrates on biostratigraphy Asmari Formation on Derak section that is located at Shiraz city with333.5 meter thickness. Asmari Formation in this section comprises of limestone with marlyinterbedded.AsmariFormation trasitionally overlies the Jahrum Formation and underlies the Razak Formation. 3 lithologic unitsidentified within the Asmari Formation in this section. In the Micropaleontological study, Asmari Formation atDerak section led to identify 31 genera and 38 species benthic foraminifera.Therfore, in this study the base of biostratigraphy is on benthic foraminifera. In biostratigraphy study, Wynd sreport (1965) and Adams and Bourgeois (1967) report are such as pattern. The first appearance ofArchaiasasmaricus and Meandropsinaanahensisand Peneroplisthomasi show the boundary between Oligocene(chattian)-Miocene (Aquetanian). Biozone no. 1 is comparable to biozone no. 2 Adams and Bourgeois(1967) andbiozone no. 59 Wynd(1965) and middelASmari in Thomas (1949) report.Biozone no. 2 identified withappearance of Nummulitesfichteli,N.intermediusalso in this zone there is Archaiasoperculiniformis. Biozone no.2 is synonymous with biozone no. 3 Adams and Bourgeois (1967) and biozone no. 57, 58 Wynd (1965). Finally,the biozone no. 2 show Oligocene and synonymeous with lower Asmari of Thomas (1949).