SHELL CONCENTRATIONS

Shell concentrations, i.e. concentrations of biomineralized invertebra te remains >2 mm in size, are widespread features of the sedimentary r ecord. They are formed by biological processes, physico-chemical proce sses, and time. Skeletal concentrations can be descriptively classifie d according to their taxonomic composition, biofabric, geometry, and c omplexity. On one hand their biostratigraphic and ecological value is often strongly reduced due to reworking and rime-averaging. On the oth er hand, their biofabric and the taphonomic signatures of the individu al components yield important information about the depositional envir onment and the final concentration process. Genetic classifications of shell concentrations are a useful tool for environmental analysis and the reconstruction of the history of sedimentary basins.