ONE Planet DTP - The rocky road to recovery – The role of microbialites in coral reef recovery after abrupt environmental change (OP20321)

Reef microbialites are excellent recorders of past sea-level and water chemistry, especially during times of environmental stress when skeletal corals (normal reef builders) are less likely to survive. This is especially evident on rapidly subsiding margins such as Hawaii (IODP Expedition 389 http://www.ecord.org/expedition389/). Microbial crusts play an essential role in the recovery of the coral reef after abrupt climate change. High-precision U-series age measurements of both corals and microbialites from Tahiti indicate that a significant time elapsed between the development of coralgal frameworks and the growth of microbialite crusts during the Last Deglaciation (Camoin et al. 2006). At present it is unclear what the significance of such a lag is and whether it exists during previous deglaciations and it is similar across a (paleo) reef transect. In this project we will work on cored material across fossil reefs that will provide a greatly expanded stratigraphic section and contain information on the role of microbialites in reef survival over the past 6 glacial cycles (Webster et al., 2009). Of specific interest would be a high resolution U-Th dating study across several microbialite-coral sections.

The cored material could potentially provide complete sections across several types of biologically controlled/induced material (e.g. corals, thrombolites, red algae crusts, microbial crusts. In this project we would explore in-situ geochemical techniques such as XPS and ToF-SIMS, for which Newcastle is at the forefront of applying these techniques to fossil rock material (Purvis et al. 2017; Purvis, van der Land, et al. 2019) to study the nature, habit and role of different types of bacteria in the different modes of carbonate lithification for microbialites. This focussed part of the study would enable us to obtain an unprecedented high-frequency (seasonal-interannual) climate signal across periods of eustatic sea-level rise, improving global paleo climate models across these intervals.