Microbialites as environmental archives from 16 ka BP to the present

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The proposed project is designed to study the microbialites of French Polynesian reefs as environmental archives in a quasi-continuous record from the post-LGM to the present. The aim is to create a consistent database for different sea-level situations and different hinterland types that will help to unravel the wealth of environmental information stored in microbialites. During IODP Expedition #310 ("Tahiti sea-level"), a reefal record from the end of the Last Glacial Maximum to 10,000 years BP was recovered that shows the peculiarity of being volumetrically dominated by microbialites. These microbialites are currently being studied by the proponent. Previous work by French colleagues focused on cores that had recovered younger reef material ("Papeete cores"; around 13,800-3000 years), and on samples from the modem environment. The proposed study has two aims: (1) closing the gap between 3000 years and the present; (2) creating comparability of the databases of all time slices. Ultimately this will help to better understand (1) the distribution of microbialites through the time interval studied, (2) changes in microbial communities, and (3) the environmental significance of microbialite occurrences.