Calcareous nannofossils of the Barremian – Aptian interval from the southeastern Tethys (Zagros Basin, West Iran) and their paleoceanographic implications: A record of Oceanic Anoxic Event 1a

Calcareous Nannofossils and Chemostratigraphy of the Early Aptian Oceanic Anoxic Event 1a From Northern Iraq

“…The Early Aptian "nannoconid crisis" was followed by a short interval virtually barren of nannoconids and dominated by other nannofossils, only later did a return of nannoconids mark the Late Aptian N. truittii (Erba, 1994, see Diagram (2), present study).The studied Early Aptian assemblages are dominated by nannoconids that drop sharply within the Discolithus litterarius nannofossil zone, which may be related to nannoconid crisis recorded in Early Aptian. This work is supported by geochemical data illustrating that this event is accompanied with decrease in CaCO3 content and higher content of Total Organic Carbon (TOC) similar to those recorded in many regions in the world and specially at Zagros Basin in Iran (Mahanipour et al, 2018(Mahanipour et al, , 2019 giving an evidence of global change during this time, like those of Early Cretaceous chalk of the North Sea (Mutterlose and Bottini, 2013). Change in lithology to marls is followed by a decline in nannoconid accompanied by an increase in TOC (Diag.…”

“…A synchronous acme event of the genera Braarudosphaera Deflandre, 1947 andNannoconus Kamptner, 1931in this section was close to the top of Early Aptian boundary as a result of shallowing of the studied interval. Morphometric data revealed dwarfing trends in the species Watznaueria barnesiae, (see Plates 1-r, s) which may suggest a possible productivity control due to increasing in the nutrient input (Mahanipour et al, 2019). The above mentioned species is also considered as an opportunistic species that are related to more stressful conditions (Aguado et al, 2016;Mahanipour et al, 2019).…”

“…Early Aptian assemblages are dominated by nannoconids with minor contributions from other nannofossil taxa. Nannoconids are robust taxa so their presence without the presence of other taxa might be the result of diagenesis (Mahanipour et al, 2019). The abundance of nannoconids drops sharply within the Discolithus litterarius nannofossil zone.…”

Sedimentological and Biological indicators of oceanic anoxic events (1d) inside upper Balambo Formation, L. Albian, northeastern Iraq

“…) . Moosavizadeh, et al, 2013;Ezampanah et al, 2013;Sarfi, et al, 2015;Mahanipour, et al, 2019 ) ‫اسب‬ ‫و‬ ‫إيطاليا‬ ‫منها‬ ‫عديدة‬ ‫بلدان‬ ‫في‬ ‫االحداث‬ ‫تلك‬ ‫بعض‬ ‫سجلت‬ ‫كما‬ ، ‫وتركيا‬ ‫انيا‬ ( ‫العالم‬ ‫بلدان‬ ‫من‬ ‫وغيرها‬ ‫وتونس‬ Yilmaz, 2007;Tiraboschi et al, 2009;Garcı´a-Mondejar et al, 2009;Ben Fadhel et al, 2011;Khalifa et al, Arthur and Sagman, 1994;Khalifa et al, 2018;Takashima et al, 2004 Arthur and Sagman, 1994;Takashima et al, 2004 ) .…”