Multivariate analysis of taphonomic data in Lower Jurassic carbonate platform (northern Italy)

Taphonomical analysis on skeletal concentrations and taphofacies has been carried out in the Lower Jurassic deposits of the Trento carbonate platform (northern Italy). The interpretation of the taphonomic categories used has been refined applying three statistical processes to the semi-quantitative values of taphocharacter abundance in eight types of skeletal concentrations. Analysis of correlation allowed the taphocharacters to be subdivided into four genetic categories: (1) palaeobiological processes on shelly ground; (2) palaeobiological activity on the substrate; (3) mechanical processes induced by currents; (4) infilling processes induced by currents. Cluster analysis on the eight types of skeletal concentrations defined six genetic processes. Moreover, principal-components analysis offered three factors which explained 75% of the variance. Factor 1 shows the contribution of hydrodynamic vs. bioturbation processes in the genesis of the resulting skeletal concentration. Factor 2 displays the degree of transport undergone by bioclasts before burial. Finally, factor 3 points out the dominance of superficial taphodistortion and colonization of the substrate, or deeper colonization in the substrate. Numerical analysis on taphonomical data has been proved to be a powerful tool for palaeoenvironmental studies, thereby aiding in the understanding of the shell beds genetic processes.