Sequence Stratigraphic Analysis of the Middle Paleocene-Middle Eocene in the Sulaimani District (Kurdistan Region), North Iraq

Abstract

The Paleocene-Eocene sequence is of great importance as oil reservoir in the Kurdistan region (North Iraq). Seven studied sections have been selected at the boundary between the high and low folded zagros zones. The successions are represented by the mixed siliciclastic-carbonates of the Kolosh and Sinjar formations overlain by red clastics of the Gercus Formation. Three facies associations were identified from Paleocene age strata in addition to three planktonic for aminifera biozones (P3, P4 & P5) and shallow benthic zone SBZ.5 & 7. However, the shallow benthic zone 9 & 10 are identified from three facies associations from Eocene strata. The Paleocene Eocene Thermal Maximum (PETM) is evidenced by the disappearance of the deep benthic foraminifera and the decrease of the planktonic foraminifera associated with notable increase of large foraminifera. The studied sequences indicate the presence of one 2nd order depostional cycle that includes six 3rd order cycles. It is in turn subdivided into ten 4th order depositional sequences. Sequence boundary type one recorded in the base and the top of the studied sequences. All in all, the facies associations and biostratigraphic data point to a shallowing upward sequence from relatively deep marine flysch (Kolosh Formation) to ramp carbonates (Sinjar Formation) and then to red molasses of the Gercus formation or evaporites of the Sagerma unit which almost reflects six stages of the foreland evolution, from Middle Paleocene to Middle Eocene time.