Journal article

Investigating controls on boron isotope ratios in shallow marine carbonates

Shuang Zhang, Michael J Henehan, Pincelli M Hull, R Pamela Reid, Dalton S Hardisty, Ashleigh VS Hood, Noah J Planaysky



The boron isotope-pH proxy has been widely used to reconstruct past ocean pH values. In both planktic foraminifera and corals, species-specific calibrations are required in order to reconstruct absolute values of pH, due to the prevalence of so-called vital effects — physiological modification of the primary environmental signals by the calcifying organisms. Shallow marine abiotic carbonate (e.g. ooids and cements) could conceivably avoid any such calibration requirement, and therefore provide a potentially useful archive for reconstructions in deep (pre-Cenozoic) time. However, shallow marine abiotic carbonates could also be affected by local shifts in pH caused by microbial photosynthesis ..

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Funding Acknowledgements

We thank Donald Penman, Dan Asael and Leanne Elder for assistance in the laboratory. We thank Bob Ginsburg for provision of Belize cement sample material. Mathis P. Hain is thanked for his help in estimating pK<INF>B</INF>* values in different solution chemistries. Peter Swart is thanked for XRD analyses. Simon D'Haenens is thanked for help with C-O isotope analysis. Jamie Foster is thanked for help with sample collection and many fruitful discussions. Thanks to Bahamas Marine EcoCentre for logistical support at Darby Island. Noah J. Planaysky acknowledges funding from the NASA Alternative Earths Astrobiology Institute, the Alfred P. Sloan Foundation and Yale University. Michael J. Henehan acknowledges financial support from the Yale Peabody Museum. Ashleigh v.S. Hood acknowledges support from a NASA Astrobiology Institute Postdoctoral Fellowship. We thank Simone Kasemann and two other anonymous reviewers for their input in improving the manuscript.