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Enhanced Research Activities in Stratigraphy

Final Report Summary - ERAS (Enhanced Research Activities in Stratigraphy)

Stratigraphy is the backbone of Earth Sciences and robust stratigraphic correlations are essential in enabling sediments to be correlated, the timing of events to be understood and rates of change to be calculated. All scientists working on palaeoenvironmental and geological reconstructions of the Earth require an age model to put their own scientific investigations into a temporal framework. As such there is a critical need for high resolution biochronology and calibration to independent age control. Planktonic foraminifera are calcareous marine zooplankton and their abundance, distinctive
morphologies and excellent evolutionary record have left a long and valuable marine fossil record that can be ready utilized in biostratigraphy. Planktonic foraminifera have many characteristics considered ideal for biostratigraphic index fossils – morphologically distinct, diverse, rapidly evolving, highly abundant, often globally distributed and high preservation potential. Extinction and evolutionary events (bioevents) in planktonic foraminifera are extensively employed in regional and global biostratigraphy and correlations. Thus planktonic foraminiferal bioevents (along with calcareous nannofossils) are an incredibly powerful and well established tool to date marine sediments and are a fundamental component of Cenozoic chronostratigraphy.

Applying an age to evolutionary or extinction events of marine microfossils relies upon sediments with continuous sedimentation and a clearly defined magnetostratigraphy or cyclostratigraphy. The calibration of planktonic foraminiferal bioevents has been based largely on correlations to the
magnetostratigraphy in Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) cores, as well as outcrop sections. However, the accuracy and precision of Cenozoic planktonic foraminiferal bioevents varies considerably, and many studies are qualitative investigations (presence or absence), low resolution (>400 kyr) and/or from DSDP sites that have poor and incomplete recovery or ambiguous magnetostratigraphy. Deficiencies in the tropical planktonic foraminiferal zonal schemes have been discovered through biostratigraphic investigations and taxonomic developments (Wade et al., 2011), indicating some rare but distinctive taxa are poorly calibrated. The weakness of the biostratigraphic calibrations becomes increasingly obvious as high resolution quantitative studies are conducted on oceanic cores with high sedimentation rates.

The overall goal of “Enhanced Research Activities in Stratigraphy” (ERAS) was to significantly advance Cenozoic biochronology by constraining the timing of planktonic foraminiferal bioevents, particularly focusing on crucial gaps and limitations in the current status of Cenozoic planktonic foraminiferal biochronology. Through ERAs we have been conducting biostratigraphic analysis of planktonic foraminiferal assemblages from the Eocene through Pleistocene obtained from multiple ocean drilling sites to significantly enhance the present status of the biochronology. Biostratigraphy based on sound taxonomy is the foundation for generating a chronostratigraphic age model. Thus, we need to clearly define how will tell apart ‘species A’ from ‘species B’. We have concentrated on Oligocene and early Miocene planktonic foraminifera (~34 to 20 million years ago) as this interval required significant taxonomic revision. The stratigraphic ranges of over 125 species have been constrained and are presented in the forthcoming Atlas of Oligocene Planktonic Foraminifera (Wade et al., in press).

We have utilised certain ocean records extensively as part of ERAs. Integrated Ocean Drilling
Program (IODP) Sites U1334 and U1338 recovered Oligocene and Miocene sediments with high sedimentation rates (30m/myr), continuous recovery, magnetostratigraphic control and orbital cyclicity (Pälike et al., 2010). Planktonic foraminiferal are abundant and assemblages are diverse, allowing for studies of foraminiferal biostratigraphy and biotic evolution. Selected bioevents are tied to the magneto- and cyclo-stratigraphies to notably refine the biochronology (Wade et al., 2016; King and Wade, 2017) and provide a reference stratigraphy for the tropical Pacific Ocean.

We have produced detailed recalibrations of planktonic foraminiferal bioevents which will contribute to future developments of the Cenozoic integrated time scale. We have also examined microfossil
assemblage changes to determine biotic change through time. Research conducted through ERAs will have far-reaching significance in evaluating the validity and limitations of biostratigraphic events. The results are made freely available via published articles, and deposition in relevant databases.

Immediate beneficiaries will be those that use planktonic foraminiferal biostratigraphy to date and correlate sediments – this is mainly academics using marine sediments, the oil exploration industry and stratigraphic service companies serving those industries. Our biostratigraphic revisions will
directly impact foraminiferal specialists in commercial operations. The 187 Cenozoic planktonic foraminiferal bioevents and charts compiled by Wade et al. (2011) are already incorporated into biostratigraphic reference works, the Geological Time Scale (Gradstein et al., 2012) and commercial databases (e.g. Stratabugs, a biostratigraphic data management software package which is used by industry worldwide).

Improved taxonomic constrains, biostratigraphic calibrations and scanning electron microscope (SEM) images are being assimilated into Mikrotax
funded through a Natural Environment Research Council innovation award “Planktonic Foraminifera@Nannotax: A freely available web resource for foraminifera taxonomy and biostratigraphy” (NE/N017900/1). Through Mikrotax we are developing an illustrated online portal of planktonic foraminifera taxonomy and biostratigraphy. PetroStrat, Network Strat, Shell and RPS Energy are industry partners on the Mikrotax project.

Our results will be incorporated into commercial databases and biostratigraphic reference works, such as the upcoming "The Geological Time Scale 2020", which is the definitive source of
information on global dating and correlation. They will also be incorporated into to future incarnations, which are planned, of the successful Natural Environment Research Council Advanced Training Short Course: "Taxonomy and biostratigraphy of Cenozoic planktonic foraminifera" (NE/N019024/1 and NE/P020178/1). This one-week course ran in February 2017 (website: and twelve students/early career scientists participated utilising material from expeditions around the world to indicate taxonomic concepts and important biostratigraphic species. Following the success of the course in 2017, it will run again February 2018 and likely beyond.

Further details are available through Professor Bridget Wade, Department of Earth Sciences,
University College London, Gower Street, London, WC1E 6BT, UK. Email: b.wade at