Skip to content

Research at St Andrews

The skeletal geochemistry of the sclerosponge Astrosclera willeyana: implications for biomineralisation processes and palaeoenvironmental reconstruction

Research output: Contribution to journalArticle


To investigate the controls on the geochemistry of aragonitic sclerosponge skeletons, we used secondary ion mass spectrometry (SIMS) to analyse an Astrosclera willeyana specimen. The high spatial resolution of SIMS allows the independent analysis of the two key crystal structures in the skeleton i.e. the fused spherulites (formed intracellularly and fused together at the surface of the skeleton) and the epitaxial backfill (deposited extracellularly at the base of the sponge tissue). We analysed Sr/Ca, Mg/Ca and Ba/Ca across a short (~ 5 mm) transect of fused spherulites which represented several years growth. We observe cyclical variations (with a length of 0.1 to 0.6 mm in both Sr/Ca and Mg/Ca in some (but not all) sections of the transect. The observed ranges of Sr/Ca and Mg/Ca over the presumed seasonal cycles are ~ 9.5 to 11.5 mmol mol− 1 and 0.6 to 1.0 mmol mol− 1 respectively. The annual seawater temperature range at the study site is ~ 4.3 °C, so the inferred temperature sensitivity of skeletal Sr/Ca and Mg/Ca is ~ 0.5 mmol mol− 1 °C (or 5% °C− 1) and ~ 0.1 mmol mol− 1°C (or 13% °C− 1) respectively. This is higher than observed in most previous sclerosponge studies or anticipated from studies of synthetic aragonite. This indicates that the chemistry of the A. willeyana skeleton is affected by one or more additional influences, besides temperature, which are currently unresolved. The pH of the precipitating fluid, estimated from skeletal δ11B, is ~ 8.1–8.2 for both fused spherulites and epitaxial backfill. Epitaxial backfill contains significantly higher Sr/Ca, Mg/Ca and B/Ca and significantly lower Ba/Ca than the fused spherulites but Sr/Ca and Mg/Ca are positively correlated by the same relationship in both skeletal features. This suggests that the geochemistry of each feature is predominantly controlled by a common process. This is unlikely to be Rayleigh fractionation, which is indicated by negative correlations between Sr and Mg in aragonite.


Original languageEnglish
Pages (from-to)70-77
Number of pages8
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Early online date26 Oct 2011
Publication statusPublished - Jan 2012

Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by author

  1. The characteristics and biological relevance of inorganic amorphous calcium carbonate (ACC) precipitated from seawater

    Evans, D., Webb, P. B., Penkman, K., Kroger, R. & Allison, N., 7 Aug 2019, In : Crystal Growth & Design. 19, 8, p. 4300-4313

    Research output: Contribution to journalArticle

  2. The effect of ocean acidification on tropical coral calcification: insights from calcification fluid DIC chemistry

    Allison, N., Cole, C., Hintz, C., Hintz, K., Rae, J. & Finch, A., 10 Oct 2018, In : Chemical Geology. 497, p. 162-169 8 p.

    Research output: Contribution to journalArticle

  3. Effects of seawater pCO2 and temperature on calcification and productivity in the coral genus Porites spp. an exploration of potential interaction mechanisms

    Cole, C., Finch, A. A., Hintz, C., Hintz, K. & Allison, N., Jun 2018, In : Coral Reefs. 37, 2, p. 471-481 11 p.

    Research output: Contribution to journalArticle

Related by journal

  1. Palaeogeography, Palaeoclimatology, Palaeoecology (Journal)

    Michael Ian Bird (Member of editorial board)
    2006 → …

    Activity: Publication peer-review and editorial work typesEditor of research journal

Related by journal

  1. Palynology and micropalaeontology of the Pliocene - Pleistocene transition in outcrop from the western Caspian Sea, Azerbaijan: potential links with the Mediterranean, Black Sea and the Arctic Ocean?

    Richards, K., van Baak, C. G. C., Athersuch, J., Hoyle, T. M., Stoica, M., Austin, W. E. N., Cage, A. G., Wonders, A. A. H., Marret, F. & Pinnington, C. A., 15 Dec 2018, In : Palaeogeography, Palaeoclimatology, Palaeoecology. 511, p. 119-143

    Research output: Contribution to journalArticle

ID: 16504220