TITLE:
Facies Interpretation, Depositional Environment and Sequence Stratigraphy of the Sartakht Formation in the Bakhshi Section, Located in Kalmard Block, East-Central Iran
AUTHORS:
Bibi Haniyeh Emraninasab, Mohammad Hossein Adabi, Mahmoodreza Majidifard, Nader Kohansal Ghadimvand
KEYWORDS:
Middle Permian, Kalmard Block, Sartakht Formation, Depositional Environment, Sequence Stratigraphy
JOURNAL NAME:
Open Journal of Geology,
Vol.6 No.5,
May
30,
2016
ABSTRACT: Permian rocks in Kalmard block are recognized with Khan Group, enjoying
various characteristics in different outcrops. This group is made up of three
informal formations, namely Chili, Sartakht and Hermez. Middle Permian deposits
(Sartakht formation) are composed chiefly of sandstone and carbonate rocks.
This formation is composed of 58.6 m sandstone and dolomitic limestone in the
Bakhshi section. Lower Permian carbonate deposits (Chili formation) unconformably
underlie this formation while lateritic paleosols of upper Permian (Hermez
formation) are depicted overlying an erosional unconformity above this
formation. According to lithologic and microscopic investigations, the deposits
of Sartakht formation can be divided into 2 siliciclastic petrofacies and 12
carbonate microfacies. Field observations, along with microscopic examinations,
have resulted in identifying tidal flat, lagoon, shoal and open marine
environments in the rocks of the studied formation. Vertical changes of microfacies
and depth variation curve point to the high thickness of the microfacies of
lagoon and shoal environments and low thickness of the microfacies of tidal
flat and open marine environments. The carbonate-siliciclastic sequence of
Sartakht formation is made up of a third-order depositional sequence, separated
from carbonate depositions of lower Permian (Chili formation) and lateritic
paleosols of upper Permian by type 1 sequence boundary (SB1). Siliciclastic
deposits include LST system tract, and carbonate microfacies involve TST and
HST system tracts, separated from each other by MFS. Sartakht formation rocks
in Bakhshi section are deposited in a low-angle homoclinal ramp, mostly in the
inner ramp, located in the south of Paleotethys Ocean. The depositional
sequence identified in Sartakht formation points to the age of middle Permian,
conforming to middle Absaroka II supersequence. The upper erosional boundary
between Sartakht and Hermez formations conforms to the global-scale sea level
fall.