جستجوی مقالات مرتبط با کلیدواژه « تاقدیس گورپی » در نشریات گروه « زمین شناسی »

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.

Pabdeh Formation has been investigated in three sections viz. the Type Section, Tang-e Hatti and the northern limb of Gurpi Anticline within the Zagros Sedimentary Basin with emphasis on calcareous nannofossils. Study of microscope slides prepared from the 1508 collected samples resulted in determination of 256 species belonging to 59 genera from 22 families of nannofossils and biostratigraphic classification was carried out based on their stratigraphic distribution. According to Martini (1971) zonal scheme, presence of NP4-NP23 nannofossil zones at the Type Section, and NP5-NP23 nannofossil zones at both Tang-e Hatti and northern limb sections have been ascertained thus indicating ‌‌Early Paleocene to Early Oligocene age for the Pabdeh Formation at these three localities. Calcareous nannofossil assemblages reveal sedimentation of Pabdeh Formation occurred in an oligotrophic, warm water environment during Paleocene-Eocene which was later on replaced by a relatively cooler water condition in Oligocene times.