PCI Paleontology

Title *

Evidence of high Sr/Ca in a Middle Jurassic murolith coccolith speciesuse asterix (*) to get italics

Authors *

Baptiste Suchéras-Marx, Fabienne Giraud, Alexandre Simionovici, Rémi Tucoulou, Isabelle DanielPlease use the format "First name initials family name" as in "Marie S. Curie, Niels H. D. Bohr, Albert Einstein, John R. R. Tolkien, Donna T. Strickland"

Year *

2020

Picture *

Abstract *

<p>Paleoceanographical reconstructions are often based on microfossil geochemical analyses. Coccoliths are the most ancient, abundant and continuous record of pelagic photic zone calcite producer organisms. Hence, they could be valuable substrates for geochemically based paleoenvironmental reconstructions but only Sr/Ca is exploited even if it remains poorly understood. For example, some murolith coccoliths species have very high Sr/Ca compared to the common 1-4 mmol/mol recorded in placolith coccoliths. In this study, we analyzed the elemental composition of the Middle Jurassic murolith *Crepidolithus crassus* by synchrotron-based nanoXRF (X-ray Fluorescence Spectroscopy) mapping focusing on Sr/Ca and compared the record to two placolith species, namely *Watznaueria contracta* and *Discorhabdus striatus*. In *C. crassus*, Sr/Ca is more than ten times higher than in both placoliths and seems higher in the proximal cycle. By comparison with the placoliths analyzed in the same analytical set-up and from the same sample, we exclude the impact of the diagenesis and seawater Sr/Ca to explain the high Sr/Ca in *C. crassus*. Based on comparisons to *Pontosphaera discopora* and *Scyphosphaera apsteinii* which also have high Sr/Ca, it seems more likely that high Sr/Ca in *C. crassus* is either due to the vertical elongation of the R-units of the proximal cycle or related to the action of the special polysaccharide controlling the growth of those vertically elongated R-units that may have affinities to Sr 2+. In order to apply the Sr/Ca proxy to muroliths, further investigations are needed on cultured coccoliths.</p>

Indicate the full web address (DOI or URL) giving public access to these data (if you have any problems with the deposit of your data, please contact contact@paleo.peercommunityin.org). In case all raw data are included in the preprint, indicate the DOI or URL of the preprint. *

https://doi.org/10.1594/PANGAEA.913826You should fill this box only if you chose 'All or part of the results presented in this preprint are based on data'. URL must start with http:// or https://

Indicate the full web address (DOI or URL) giving public access to these scripts (if you have any problems with the deposit of your scripts, please contact contact@paleo.peercommunityin.org). In case all raw scripts are included in the preprint, indicate the DOI or URL of the preprint. *

You should fill this box only if you chose 'Scripts were used to obtain or analyze the results'. URL must start with http:// or https://

Indicate the full web address (DOI, SWHID or URL) giving public access to these codes (if you have any problems with the deposit of your codes, please contact contact@paleo.peercommunityin.org). In case all raw codes are included in the preprint, indicate the DOI or URL of the preprint. *

You should fill this box only if you chose 'Codes have been used in this study'. URL must start with http:// or https://

Keywords (optional)

Calcareous nannofossils; Coccoliths; ESRF; Muroliths; Sr/Ca; Ultrastructure; XRF

Methods that require specific expertise (optional)

NonePlease indicate the methods that may require specialised expertise during the peer review process (use a comma to separate various required expertises).

Thematic fields *

Microfossils, Micropaleontology, Nanofossils

Suggested reviewers - Suggest up to 10 reviewers (provide names and Email addresses). (Optional)

e.g. John Doe john@doe.com

No need for them to be recommenders of PCIPaleo. Please do not suggest reviewers for whom there might be a conflict of interest. Reviewers are not allowed to review preprints written by close colleagues (with whom they have published in the last four years, with whom they have received joint funding in the last four years, or with whom they are currently writing a manuscript, or submitting a grant proposal), or by family members, friends, or anyone for whom bias might affect the nature of the review - see the code of conduct

Opposed reviewers - Suggest up to 5 people not to invite as reviewers. (Optional)

e.g. John Doe john@doe.com

Submission date

2020-05-18 16:11:35

Recommender

Antonino Briguglio

Reviewers

or Register
Submit a preprint

FOLLOW US

MANAGING BOARD

MEMBER OF

INDEXED BY