Planktic foraminifera form their shells via metastable carbonate phases

D. E. Jacob*, R. Wirth, O. B.A. Agbaje, O. Branson, S. M. Eggins

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    78 Citations (Scopus)

    Abstract

    The calcium carbonate shells of planktic foraminifera provide our most valuable geochemical archive of ocean surface conditions and climate spanning the last 100 million years, and play an important role in the ocean carbon cycle. These shells are preserved in marine sediments as calcite, the stable polymorph of calcium carbonate. Here, we show that shells of living planktic foraminifers Orbulina universa and Neogloboquadrina dutertrei originally form from the unstable calcium carbonate polymorph vaterite, implying a non-classical crystallisation pathway involving metastable phases that transform ultimately to calcite. The current understanding of how planktic foraminifer shells record climate, and how they will fare in a future high-CO2 world is underpinned by analogy to the precipitation and dissolution of inorganic calcite. Our findings require a re-evaluation of this paradigm to consider the formation and transformation of metastable phases, which could exert an influence on the geochemistry and solubility of the biomineral calcite.

    Original languageEnglish
    Article number1265
    JournalNature Communications
    Volume8
    Issue number1
    DOIs
    Publication statusPublished - 1 Dec 2017

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