Coccolith Chemistry: A Flow-Through Analysis

Coccoliths not only hold much promise as a source of new and exciting geochemical data, but also provide an elegant test case for models of biomineral trace-metal incorporation due to their simple construction. Coccoliths are formed from a small number of single crystals growing from a ring of alternating vertical and radially oriented calcite nucleation sites. Microprobe and electron backscatter analysis hint at crystallographically discrete trace metal distribution coefficients. Here we investigate inhomogeneities within the calcite of coccolithophore monocultures using continuous-dissolution trace-metal analysis, combined with repeated AFM imaging of individual dissolving coccoliths. We present coccolith trace-metal distribution coefficients, explore the potential of coccolith calcite as a recorder of palaeoenvironmental data, and consider crystallographic controls over trace- metal chemistry.