A revised calcareous nannofossil biozonation for the Lower Jurassic (Hettangian–Lower Pliensbachian) of NW Europe
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The Mochras core, UK, an historic reference site for the study of Early Jurassic cal-careous nannofossils, has been reinvestigated here across the Hettangian to Lower Pliensbachian. Both relative and absolute abundances of 24 calcareous nannofossil species reveal patterns and occurrences that define not less than 37 defined biohorizons. However, due to the low abundance of many of those species towards the base and top of their stratigraphical range, we observe large inconsistencies in first and last occurrences of these species. Instead, we consider records of first consistent and last consistent occurrences (FCOs and LCOs), as well as base and top of acme events, as more reliable biohorizons. Accordingly, we assess the reliability of our biohorizons and show that, in addition to previously established zonal and sub-zonal biomarkers, nine non-zonal biohorizons prove to be robust. Based on that, an updated biozonations scheme with additional subzones for NJB has been proposed and tested against other localities.
Originalsprog | Engelsk |
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Artikelnummer | 56.3.4 |
Tidsskrift | Lethaia: An International Journal of Palaeontology and Stratigraphy |
Vol/bind | 56 |
Udgave nummer | 3 |
Antal sider | 20 |
ISSN | 0024-1164 |
DOI | |
Status | Udgivet - 2023 |
Bibliografisk note
Funding Information:
Emanuela Mattioli is acknowledged for her tremendous help following and discussing the taxonomy of the species identified throughout this study. Many thanks to an anonymous reviewer for the constructive and useful comments and also to Clemens V. Ullmann for managing, preparing and distributing sample bags of Mochras to us. This study is part of the Early Jurassic Earth System and Timescale (JET) research project.
Publisher Copyright:
© 2023 Author(s).
ID: 382857935