52.
The Kopet-Dagh sedimentary basin is located in northeast of Iran and southeast of Turkmenistan in the Middle East. The Khangiran formation represents the last marine deposition in the Kopet-Dagh sedimentary basin. The early Eocene planktonic and benthic foraminifera from the Khangiran formation which belongs to the lower 376 m thickness of this formation are identified and biostratigraphically evaluated. Due to rarity of
Morozovella species, planktonic foraminiferal zonation was difficult to determine in this formation. The determination of upper part of the late Paleocene for the lower 124 m of this formation is according to the lowest occurrence of
Acarinina sibaiyaensis species. From E
5 to near middle of E
7 biozone, increasing trend of
Acarinina frequency and a peak in
Morozovella species and decreasing trend of frequency of
Subbotina and
Pseudohastigerina species indicate the warm and oligotrophic condition of the seawater during sedimentation of the studied interval. Toward the Ypresian-Lutetian boundary, the increasing trend of
Pseudohastigerina and
Subbotina species and decreasing in frequency of
Acarinina species suggest the low-oxygen level, eutrophic and intermediate condition of the seawater. In this formation, the high abundance of the epifaunal taxa such as
Anomalinoides spp.,
Cibicidoides spp.,
Gyroidinoides spp., and
Lenticulina spp. from the base (late Paleocene sediments) up to E
6 biozone reflects oligotrophic and oxic shallow water conditions. The occurrence of several peaks in abundance of
Bulimina and
Uvigerina species at the Ypresian/Lutetian boundary suggests eutrophic condition. These paleoecological conditions could be correlated with fluctuations in the numbers of the planktonic foraminifera.
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