Analysis of Microfacies , Sedimentary Environments and Sequence Stratigraphy of Pabdeh Formation, in type section, Zagros

Abstract

Type section of Pabdeh Formation (Late Paleocene- Early Oligocene) is located in the Gurpi anticline, Zagros, Khouzestan Province. Lithologically Pabdeh Formation consists of purple and white to yellowish marl, marly limestone and thin- to thick- bedded limestone, rich in pelagic foraminiferas. Pabdeh Formation conformably overlies Gurpi Formation and is conformably overlained by Asmari Formation. Petrographic studies, description and microfacies analysis specially hemipelagic, pelagic and calciturbidite facies of Paleocene to Lower Oligocene indicate that Pabdeh Formation was deposited in a deep marine basin. Field observations, facies studies and sequence studies resulted in identification of stratal key surfaces of sequence stratigraphy such as sequence boundary, maximum flooding surface, transgressive surface, system tracts and 9 depositional sequences. Sequence P1, P2 and LST, FSST of sequence P3 are of Paleocene in age, based on identification of planktonic foraminifera, TST, HST and FRWST of sequence P3 and sequences P4, P6, P7 and P8 were deposited during Eocene, and sequence P9 suggest an age of Upper Eocene- Lower Oligocene. All sequences begin with SB2 and except of sequence P3 and P4 , SB2 and Ts surfaces coincide with each other. Deepest mfs is belongs to the sequence P3; due to the remarkable abundance of glauconite minerals. Relative sea- level curves in most sequences, except for sequences P3, P8 and P9 exactly correlate with standard global sea level curves. The role of synsedimentary tectonic activities and sea-level oscilations ,probably, are responsible for deposition of sequences P3, P8 and P9.

Keywords

• Gurpi anticline
• Pabdeh Formation
• Sedimentary Environment
• Sequence stratigraphy
• Paleocene- Oligocene