Taphonomy of Clypeaster fragments: preservation and taphofacies

Abstract

The preservation of echinoid fragments of the common echinoid genus Clypeaster recovered from bulk sediment samples is used to explore the possibilities of recognizing taphonomic patterns and establishing taphofacies within a shallow water carbonate environment (Northern Bay of Safaga, Red Sea, Egypt). This is accomplished by the comparison and quantification of the taphonomic signatures of numerous fragments of roughly similar size. The main taphonomic processes observed are abrasion and destruction of plate surfaces, including tubercles and plate edges. Encrustation, especially by foraminifera, can be common and intense. Intraplate fracturing and surface features, such as scratch marks, were also quantified. Four different taphofacies with different characteristic signatures were separated using a cluster analysis of cumulative taphonomic grades. The distribution of taphofacies clearly reflects the topographic complexity of the study area and can be explained by ambient environmental parameters that reflect the general picture of wave and current intensities and sedimentation patterns. The potential use of taphofacies analysis as an independent measure of environmental heterogeneity in palaeoecological studies is confirmed in that taphofacies analysis can reveal parameters not immediately obvious when investigating the textural and biotic characteristics of a sediment.