Calcareous nannofossil biostratigraphy: historical background and application in Cenozoic chronostratigraphy

Abstract

Calcareous nannofossils are considered one of the most powerful biostratigraphical tool in marine carbonate sediments especially in open ocean settings. Their origination goes at least as far back as the Triassic (ca. 220 Ma) when they first biomineralized and produced calcite skeletons. Since then, they have evolved rapidly showing widespread biogeographical distributions. Starting from the 1950s, changes in calcareous nannofossil assemblages have been used to date rocks and sediments and a fundamental step was achieved two decades later with the publication of the first comprehensive biostratigraphical schemes. Standardized quantitative counting methods, unambiguous taxonomy as well as highly resolved data sets provide high-quality biostratigraphical datums which, in turn, result in the precise positioning of calcareous nannofossil biohorizons and in the construction of reliable biostratigraphical frameworks. Here, we use recently published Cenozoic biozonations as a framework to present an overview of the calcareous nannofossil biohorizons which are used in chronostratigraphy to denote Cenozoic Global Standard Stratotype-section and Point

The Early to Middle Eocene Transition: An Integrated Calcareous Nannofossil and Stable Isotope Record From the Northwest Atlantic Ocean (Integrated Ocean Drilling Program Site U1410)

“…The biostratigraphic schemes adopted are those of Martini (), Okada and Bukry (), and Agnini et al (). These quantitative, highly resolved data sets allow for the analysis of biostratigraphic reliability (e.g., Agnini et al, ; Raffi, ). This is particularly relevant for the lower and middle Eocene intervals, where numerous marker species have been found to be rare or even absent in some depositional settings or show sporadic abundance patterns around their level of evolutionary emergence and/or extinction.…”

Biostratigraphy and Paleoenvironmental Reconstruction at the Gebel Nezzazat (Central Sinai, Egypt): A Paleocene Record for the Southern Tethys

“…Calcareous nannofossils are useful tool for high-resolution biozonation and correlation of Cenozoic sediments [39][40][41][42][43][44][45][46][47]. The "Standard" Zonation Scheme of [39] for the Paleocene has been adopted in the present study with slight modifications.…”

“…In this study, C. tenuis includes specimens that have "feet" where their axial crossbars meet the brim. Some authors [46][47][48] excluded C. danicus from being a zonal guide as a consequence of the discrepancies related to the delineation of C. danicus, C. edwardsii, C. asymmetricus, and C. consuetus [48,[70][71][72][73].…”

A Multi-Analytical Study of an Ancient Egyptian Limestone Stele for Knowledge and Conservation Purposes: Recovering Hieroglyphs and Figurative Details by Image Analysis

“…On the basis of this assemblage, and of the absence of Tribrachiathus orthostylus, a species that characterizes the homonymous biozone [11], and of Discoaster sublodoensis (marker of the CNE6 biozone), it is possible to assign the sample to the CNE5 biozone, with a Ypresian age (lower Eocene). This is also supported by the presence of C. crassus, which appears at the top of the CNE4 biozone [11]. As for the standard biozones, still in use by many authors, the sample belongs to the biozones CP11 [12] and NP13 [13], thus confirming a Ypresian age.…”