Depositional environment and sequence stratigraphy architecture of continuous Upper Permian and Lowermost Triassic deep marine deposits in NW and SW Iran

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Type
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Title
Depositional environment and sequence stratigraphy architecture of continuous Upper Permian and Lowermost Triassic deep marine deposits in NW and SW Iran
Journal
Palaeogeography, Palaeoclimatology, Palaeoecology
Author(s)
Arefifard Sakineh, Baud Aymon
ISSN
0031-0182
Publication state
Published
Issued date
16/08/2022
Peer-reviewed
Oui
Volume
603
Pages
111187
Language
english
Abstract
The end-Permian mass extinction, the greatest biotic crisis through the Phanerozoic, caused a severe loss of
marine organisms in terms of abundance and diversity. Knowing sea level fluctuations, environmental conditions
and the sequence stratigraphic architecture of the Upper Permian deposits will enable us to reconstruct events
before the mass extinction and across the Permian/Triassic boundary in a regional and global context. The Upper
Permian deposits are examined in well-known sections in Julfa, NW Iran and Abadeh in SW Iran using
microfacies analyses, depositional environment interpretation and sequence stratigraphic framework. Detailed
petrographic examination and microfacies analyses show third- and fourth-order cycles both in Wuchiapingian
and Changhsingian deep-water distally deposited strata of Julfa and Abadeh sections. Considering Iranian tectonics
during Permian through Triassic time, there was rifting accompanied by drift and subsequent subsidence.
Tectonics was a main factor that influenced the depositional environment and sequence stratigraphic framework
in the study areas. According to previous studies, since subsidence increased in a North to SW direction during
Middle Permian through Triassic time, this effect is seen in lithologic characteristics of the Wuchiapingian with
more mid-ramp settings in Julfa Beds in Julfa area, compared to the more outer-ramp settings of the Unit 6 of the
Hambast Formation in Abadeh area. Tectonic subsidence influence was also responsible for creating the fourthorder
cycles within third-order cycles despite the absence of common glacial events to create high-frequency
cycles in Iran during the Lopingian. The Lopingian successive deepening in Iran caused the faunal changes
which is evident in decreasing trend of body size and biodiversity in brachiopods and ammonoids and also marks
the beginning of the transgressive system tracts during this time interval.
Keywords
Paleontology, Earth-Surface Processes, Ecology, Evolution, Behavior and Systematics, Oceanography
Create date
25/08/2022 18:13
Last modification date
26/08/2022 6:41
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