Diatom preservation: differential preservation of sedi- mentary diatoms in two saline lakes

The integrity of all sedimentary diatom assemblages is influenced to some degree by taphonomic processes. Recognising these processes with regard to preservation pathways for diatom assemblages and for individual species can be instructive for interpreting sediment core diatom records. Diatoms deposited in saline lakes are usually particularly exposed to both chemical and physical processes that promote poor preservation. Aspects of diatom preservation are explored in two markedly different saline lakes (one in North America and one in Egypt) and observations are used to make some initial inferences about diatom preservation. By applying dissolution indices to evaluate differences in valve preservation states between assemblages and between species in an objective manner, sedimentation processes and valve characteristics are indicated important implications for interpreting sedimentary diatom records. It is further argued that, by taking account of diatom dissolution states, both qualitative and quantitative inferences about past environments can be extended.