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Tavakok Anticline
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Tahereh Shokouhifar   , Nader Kohansal ghadim vand *1 , Davood Jahani , Mohammad Ali Arian |
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Abstract: (9 Views) |
The Asmari Formation (Oligocene–Lower Miocene) is the most important carbonate reservoir of the Zagros Basin and one of the most prolific hydrocarbon reservoirs in the world; consequently, a precise understanding of its microfacies, depositional environment and sequence-stratigraphic framework in any given section carries both fundamental and applied (reservoir) value. In the present study, a continuous 568-m-thick section of the Asmari Formation was examined on the flank of the Tavakok anticline, located 15 km northwest of Izeh (Khuzestan Province) within the Izeh structural zone of the Zagros fold–thrust belt. The section was sampled systematically at regular 2-m intervals, and a total of 263 rock samples were studied petrographically and micropaleontologically. On the basis of depositional texture (Dunham, 1962; Embry & Klovan, 1971) and skeletal assemblages, five main microfacies (MF1–MF5) were identified and assigned to four principal depositional environments—lagoon, shoal, shallow open marine (middle ramp) and deep marine (outer ramp)—together with an event-driven tempestite sub-environment. The complete absence of tidal-flat and evaporitic facies, combined with the gradual and continuous transition between facies belts, indicates deposition on a homoclinal carbonate ramp within an open-marine setting lacking any effective barrier. The continuous occurrence of Borelis melo from 562 m up to 1 m establishes a Burdigalian age for the whole succession, which can be interpreted as a single complete third-order depositional sequence composed of a retrogradational, deepening-upward transgressive systems tract (TST) culminating at a maximum flooding surface (MFS), overlain by a progradational, shallowing-upward highstand systems tract (HST). Tempestite facies within the transgressive interval record high-energy storm events and the transport of skeletal debris from the inner ramp to the middle–outer ramp. The results are fully consistent with the regional pattern documented for the Burdigalian part of the Asmari Formation in the Izeh Zone and the Dezful Embayment, and reaffirm the dominance of a low-gradient carbonate ramp during deposition of the upper Asmari Formation.
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Article number: 3 |
| Keywords: Tavakok anticline, Asmari Formation, microfacies, homoclinal carbonate ramp, sequence stratigraphy, Izeh Zone, Zagros, Burdigalian. |
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Full-Text [PDF 3390 kb]
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Type of Study: Research |
Subject:
Special
Received: 2025/08/20
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