A refined foraminiferal biostratigraphy for the Late Campanian–Early Maastrichtian succession of northeast Iraq

Abstract

Species of the benthonic foraminiferal genus Bolivinoides provide a refined biostratigraphic biozonation for the Late Campanian to Early Maastrichtian (Late Cretaceous) Shiranish Formation in NE Iraq. Three biozones and two subzones are identified: the Bolivinoides decoratus Biozone (Late Campanian) subdivided into a lower B. decoratus Subzone and upper B. laevigatus Subzone; the B. miliaris Biozone (Earliest Maastrichtian); and the B. draco Biozone (late Early Maastrichtian). These zones can be related to the biostratigraphical interval of the Globotruncana aegyptiaca (Late Campanian), Gansserina gansseri (latest Campanian–Early Maastrichtian) and Contusotruncana contusa (late Early Maastrichtian) planktonic foraminiferal biozones. Combined, the benthonic and planktonic foraminiferal biostratigraphy enables the informal recognition of lower and upper intervals within both the Globotruncana aegyptiaca and Gansserina gansseri biozones that may be important for more refined inter-regional correlation in the Middle East and North Africa. The new Bolivinoides biozonation precisely locates the Campanian–Maastrichtian boundary in NE Iraq. The foraminiferal assemblages also constrain the timing of a shallowing marine trend in the Shiranish Formation beginning from the latest Campanian that is consistent with shallowing facies noted globally at this time.

Integrated foraminiferal biostratigraphy, bioevents and sea‐level reconstruction in the Campanian–Maastrichtian succession at Gabal Nezzazat, south‐western Sinai, Egypt

“…Global biocorrelation : This zone was correlated with the B. decoratus Zone recorded by Georgescu (2018) in the general zonation, with the same z one recorded in England (Bailey et al, 2009; Barr, 1966; Swiecicki, 1980) and in Iraq by Jaff et al (2014). It was also compared with the lower part of B. decoratus Zone defined in Germany (Hiltermann & Koch, 1950), in New Jersey (Petters, 1977), in Libya (Barr, 1970), in, Sinai, Egypt by El‐Nady (2006) and in Israel by Reiss (1954) (see Table 2).…”

“…Global biocorrelation : This zone was recorded nearly in the same stratigraphical range of that of Petters (1977) in New Jersey, of Hiltermann and Koch (1950) in Germany, of Barr (1970) in Libya, of Reiss (1954) in Israel, of (El‐Nady, 2006; Khalil, 1998) in Sinai, Egypt, and of Jaff et al (2014) in Iraq. It is also compared with B. peterssoni that is defined in England (Bailey et al, 2009; Swiecicki, 1980) and with both B. miliaris Zone and B. australis Zone recorded by Georgescu (2018) in his general zonation (see Table 2).…”

“…Bolivinoides miliaris is restricted to the earliest Maastrichtian in Iraq (Jaff et al, 2014). B. miliaris is also recorded from the same stratigraphical range in Germany (Hiltermann & Koch, 1950); in Libya (Barr, 1970) and in Sinai, Egypt (El‐Nady, 2006; Khalil, 1998).…”

Calcareous Nannofossils from the Shiranish Formation at Bekhaer anticline, Dhouk area, Northern Iraq

“…This formation has been studied by many researchers with different specializations, where [4,5] studied it with other formations based on fossils of Ostracoda, foraminifera, and some other groups. The formation was studied by relying on foraminifera fossils, such as [6,7,8,9,10,11,12,13,14,15,16,17,18,19]. The formation based on calcareous nannofossils has also been studied by [20,21,22].…”

Planktonic foraminiferal quantitative analysis across the Campanian/Maastrichtian boundary at the Pondicherry area, Cauvery Basin, Southern India

“…equivalent to the Rugoglobigerina hexacamerata Subzone (CF8b) ofLi et al (1999). Several authors assigned the FAD of R. hexacamerata in different localities to detect the Campanian/Maastrichtian boundary (C/M)(Jaff, Wiliams, Wilkinson, Lawa, & Zalasiewicz, 2014;Tantawy, Keller, Adatte, Stinnesbeck, & Kassab., 2001; …”