Calcareous index nannofossils (coccoliths) of the lowermost Paleocene originated in the late Maastrichtian

Abstract

ABSTRACT:The calcareous nannofossil species Neobiscutum romeinii, N. parvulum, and Cruciplacolithus primus, are considered in modern zonation schemes as index species for the lowermost Paleocene. Our studies, however, reveal that they are consistently present in upper Maastrichtian calcareous nannofossil zone CC26. The two Neobiscutum species were found several meters below the Cretaceous-Paleogene (K-P) boundary in cores from Brazos River (Texas) and Antioch Church (Alabama), and in outcrops at Geulhemmerberg (the Netherlands), El Kef (Tunisia), and Jebel Qurtasiyyat (Jordan). Except for the Jordanian record, the same applies to the occurrence of C. primus. These coccoliths are extremely small, ranging from 0.8 to 2.5µm for Neobiscutum and 1.5 to 3.5µm for C. primus, and they constitute less than 1% of the calcareous nannofossil association. This may explain why they were not consistently detected below the K-P boundary in earlier investigations. Since these species are not exclusively Paleocene indicators only their prominent acmes or, alternatively, the index species Biantholithus sparsus should be used to unambiguously identify the lowermost Paleocene. The geographic coverage in our study indicates that the late Maastrichtian appearances of N. romeinii, N. parvulum and C. primus are typical for marginal seas of the Northern Hemisphere.

Bioturbational redistribution of Danian calcareous nannofossils in the uppermost Maastrichtian across the K-Pg boundary at Bidart, SW France

“…Geobios 43 (2010) [569][570][571][572][573][574][575][576][577][578][579] Due to their very small size, calcareous nannofossils are comparatively easily resedimented and reworked. This fact has been brought forth in several papers on the K-Pg boundary, showing Cretaceous taxa in Danian samples and vice versa; but only occasionally has the incidence of the activity of tracemakers on calcareous nannofossils redistribution been considered, and in almost all cases this aspect has been alluded to in general terms (e.g., Thierstein and Okada, 1979;Thierstein, 1981;Smit and Romein, 1985;Henriksson, 1996;Pospichal, 1996;Romein et al, 1996;Mai et al, 2003;Bown, 2005;Lamolda et al, 2005). Thus, the role of tracemakers in the reworking of microfossils is usually underestimated.…”

Last occurrence of Abathomphalus mayaroensis (Bolli) foraminiferid index of the Cretaceous–Paleogene boundary: the calcareous nannofossil proof

“…Instead, the first occurrence of Biantholithus sparsus should be used as the certain age marker as is proposed in the zonation scheme by Varol (1998). Generally, this species is considered as rarely found (Mai et al 2003;Molina et al 2006), however, it was also noted in the Carpathians (Oszczypko et al 1995;Bubík et al 1999;Summesberger et al 1999). On the other hand, van Heck & Prins (1987) and Švábenická (2001) claimed the occurrence of B. sparsus even in the Upper Maastrichtian.…”

“…The calcareous nannofossil biostratigraphy of the K/Pg boundary is handicapped by the problem of the reworked assemblages (Bown 2005;Kędzierski et al 2011 and references cited therein) and growing evidence of some taxa such as Cruciplacolithus primus, which were previously considered as newcomers, but now as Late Maastrichtian in origin (Mai et al 2003). Similarly, the Lower Paleocene foraminiferid assemblages also comprise reworked and survivor taxa (Huber 1996;Gallala et al 2009;Slimani & Toufiq 2013).…”

“…However, Mai et al (2003) noted the Maastrichtian occurrence of Neobiscutum romeinii, N. parvulum and Cruciplacolithus primus in many sections around the world, 2-12 m below the K/Pg boundary, and claimed that none of these species can be used as the indicator of the Paleocene (see also Mai 1999;Gardin 2002). Instead, the first occurrence of Biantholithus sparsus should be used as the certain age marker as is proposed in the zonation scheme by Varol (1998).…”

Re-discovery of a “living fossil” coccolithophore from the coastal waters of Japan and Croatia

“…It has recently been shown that it also occurs in shelf sediments of Late Maastrichtian age and so should be considered a survivor species (Mai et al, 2003). Like Cyclagelosphaera it has often been regarded as an extinct genus but one species C. neohelis occurs sporadically in coastal-neritic environments (e.g.…”