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

Abstract

Calcareous nannofossils were documented from the upper part of the Cretaceous Balambo Formation in northern Iraq with the aim of determining an evidence for the Oceanic Anoxic Event. A detailed investigation of the calcareous nannofossils led to the identification of twenty-four species. Regarding these data, Discolithus litterarius (Górka, 1957) was identified at the studied interval with the age of Early Aptian. Early Aptian assemblages are dominated by nannoconids that drop sharply within the D. litterarius nannofossil zone, which may be related to the nannoconid crisis recorded in the Early Aptian in the other parts of the world. This event is coincided by a decrease in CaCO3 content and higher content of the Total Organic Carbon (TOC).

Practical Application of the Mineralogical Mapping Method for Stratigraphy of the Cretaceous Deposits of Southern Primorye (Russian Far East)

“…The formation interval of the reddish-colored sediments of the Korkinskaya Series (upper part of the Romanovskaya suite) is 93-95 Ma (the epoch of lateritic weathering), which coincides with the Cenomanian-Turonian events (OAEs-Bonarelli event, C/T OAE, OAE2,~93 Ma, [41,42,46]). Similar stratification was also noted for the Cretaceous deposits of Europe [47][48][49], Venezuela [45], Northern Iraq [50], Japan [51][52][53][54], Polynesia [55], Tibet [56,57], the Arctic [58], and other regions of the world [59][60][61][62][63][64].…”