Middle Miocene integrated stratigraphy, paleoclimatic and environmental turnover imprints from the Kurdistan Foreland Basin, N. Iraq

Abstract

Integrated stratigraphic and sedimentological analysis have been used to reconstruct the paleoclimatic and paleoenvironmental history of the nonmarine siliciclastic deposits of the Injana Formation (Langhian-Serravallian) from the Kurdistan foreland basin (N. Iraq).The transition from marine to nonmarine deposits resulted from the gradual retreat of the Neotethys seaway SE-ward, sea level change, and the rising of the Zagros Fold-Thrust Belt. The last marine foreland deposits (Consist of mixed lagoonal carbonates and evaporites) of the Fatha Formation (Burdigalian) vary from the predominated nonmarine fluvial deposits of the Injana Formation siliciclastic deposits (with predominated sandstone, mudstone, and claystone). Bioevents variations are evident in benthic foraminiferal (Ammonia beccarii, miliolides). The marine mollusca represent by pelecypods and gastropods (i.e., Ostrea latimarginata , Ostrea subangulata, Clausinella persica, Clementia sp.,Cardium spp, Acteocina spp, Turbo sp.). The ichnofossil assemblages also shows varation from predominated Planolites, Thalassinoides to Skolithos and Scoyenia. The freshwater ostracods (Cytheridella, Penthesilenula) and brackish" water ostracods (i.e., Cyprideis) have been recorded in non-marine sequences while Chrysocythere spp, are predominated in the lagoonal parasequences. Although Miocene mammals are rarely found in the Kurdistan foreland basin, recently, new terrestrial vertebrate remains were discovered, confirming the transition from marine to nonmarine depositional environments. This transition was associated with climate change from the warmest condition of the middle Miocene climate optimum (MMCO) to a colder condition. In addition, the XRD results indicate that clay mineralogy is changing, as illite-chlorite assemblages are replaced by bentonite-montmorillonite clays. The XRF results indicate the predominance of iron and silica oxides in the nonmarine deposits, whereas calcium, magnesium, sulfur oxides, and alkalis characterize the earlier marine deposits. These new results, in addition to the discovery of terrestrial vertebrate remains and the rise of the Zagros Mountains, show that the middle-late Miocene time was a critical period in shaping the present-day habitat in the NW Zagros belt. Powered by TCPDF (www.tcpdf.org)

Full text

EGU24-2570, updated on 12 Mar 2024
https://doi.org/10.5194/egusphere-egu24-2570
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
Middle Miocene integrated stratigraphy, paleoclimatic and
environmental turnover imprints from the Kurdistan Foreland
Basin, N. Iraq.
Fadhil Ameen11, Renas Koshnaw2, and Davit Vassilyan3
1University of Sulaimani, College of Science, Geology, Sulaimani, Iraq (fadhil.ameen@univsul.edu.iq)
2Department of Structural Geology and Geodynamics, Geoscience Center, University of Goettingen, Goldschmidtstrasse 3,
37077 Goettingen, Germany
3Jurassica Museum, Route de Fontenais 21, 2900 Porrentruy, Switzerland
Integrated stratigraphic and sedimentological analysis have been used to reconstruct the
paleoclimatic and paleoenvironmental history of the nonmarine siliciclastic deposits of the Injana
Formation (Langhian-Serravallian) from the Kurdistan foreland basin (N. Iraq).The transition from
marine to nonmarine deposits resulted from the gradual retreat of the Neotethys seaway SE-ward,
sea level change, and the rising of the Zagros Fold-Thrust Belt. The last marine foreland deposits
(Consist of mixed lagoonal carbonates and evaporites) of the Fatha Formation (Burdigalian) vary
from the predominated nonmarine fluvial deposits of the Injana Formation siliciclastic deposits
(with predominated sandstone, mudstone, and claystone). Bioevents variations are evident in
benthic foraminiferal (Ammonia beccarii, miliolides). The marine mollusca represent by
pelecypods and gastropods (i.e., Ostrea latimarginata , Ostrea subangulata, Clausinella
persica, Clementia sp.,Cardium spp, Acteocina spp, Turbo sp.). The ichnofossil assemblages
also shows varation from predominated Planolites, Thalassinoides to Skolithos and Scoyenia .
The freshwater ostracods (Cytheridella, Penthesilenula) and brackish” water ostracods
(i.e., Cyprideis) have been recorded in non -marine sequences while Chrysocythere spp, are
predominated in the lagoonal parasequences. Although Miocene mammals are rarely found in
the Kurdistan foreland basin, recently, new terrestrial vertebrate remains were discovered,
confirming the transition from marine to nonmarine depositional environments. This transition
was associated with climate change from the warmest condition of the middle Miocene climate
optimum (MMCO) to a colder condition. In addition, the XRD results indicate that clay mineralogy
is changing, as illite-chlorite assemblages are replaced by bentonite-montmorillonite clays. The
XRF results indicate the predominance of iron and silica oxides in the nonmarine deposits,
whereas calcium, magnesium, sulfur oxides, and alkalis characterize the earlier marine deposits.
These new results, in addition to the discovery of terrestrial vertebrate remains and the rise of the
Zagros Mountains, show that the middle-late Miocene time was a critical period in shaping the
present-day habitat in the NW Zagros belt.
Powered by TCPDF (www.tcpdf.org)