A new look at modern agglutinated benthic foraminiferal morphogroups: their value in palaeoecological interpretation

Abstract

Morphogroups offer a way of overcoming taxonomic differences and thereby making comparisons between assemblages of different geological ages. Relating morphogroups to environments has proved useful in palaeoecological interpretations. The model proposed by Jones and Charnock in 1985 has subsequently been adapted and still serves as the main reference for such palaeoecological interpretations. New data from > 400 samples from marsh to deep sea off NW Europe are used here to refine the model by providing the range of abundance of each morphogroup in each environment. It is shown that this range of variation is great so that there is considerable overlap between environments. Nevertheless, the mean values show patterns of distribution. Tubular forms (morphogroup A) are characteristic of slope environments, especially those under the influence of geostrophic currents. Morphogroup B is not common in marginal marine environments but is an indicator of shallow fjord to deep sea. The elongate forms of morphogroup C are widely distributed but C1 is especially common in marginal marine and shelf to upper slope settings. The quinqueloculine coiled C2 subgroup is characteristic of marsh and marginal marine environments in the temperate zone but around Antarctica this form is common down to 2000 m. The plano-convex, low trochospiral trochamminids of morphogroup D are typical of marshes. Therefore, these trends have application to palaeoecology of similar well-oxygenated temperate environments.