A mineralogical perspective on foraminiferal architecture: insights into a unique biosphere-geosphere interaction

Foraminifera – microscopic single-celled marine eukaryotes – are among the most productive and important biomineralizing organisms in modern oceans and play a crucial role for global carbon and nitrogen cycles. Certain types of foraminifera are capable of assembling and cementing together surrounding sediment particles to form intricate shell structures. By doing so, these so-called agglutinated foraminifera effectively create an archive of ambient mineralogical composition, which has the potential to be preserved as microfossils and endure for hundreds of millions of years. In order to evaluate the mineral grain incorporation into agglutinated foraminiferal shells and previously observed mineral selectivity, sediment samples from different locations in the Mediterranean Sea (Gulf of Naples and Haifa Bay) were analysed using powder X-ray diffraction (PXRD) and X-ray fluorescence (XRF). Additionally, the element distribution and mineral composition of agglutinated foraminifera occurring within the investigated sediments was analysed via energy dispersive X-ray spectroscopy (EDX) and Raman spectroscopy.