Quantitative taphonomic analysis and taphofacies in lower Pliocene temperate carbonate–siliciclastic mixed platform deposits (Almerı́a-Nı́jar basin, SE Spain)

Actualistic assessments emphasize the power of carrying out quantitative analysis of the taphonomic traits, as well as the use of multivariate statistical tests for the definition of taphofacies models. Nonetheless, in the palaeontological literature, taphonomic analyses are often based on qualitative observations or on semi-quantitative studies involving only a few taphonomic attributes. In this paper, a quantitative study for analyzing taphonomic signatures and proposing taphofacies in the fossil record is presented. This methodology is applied in lower Pliocene carbonate–siliciclastic mixed deposits of the Almerı́a-Nı́jar basin (SE Spain). Selected taphonomic attributes that are quantitatively analyzed are: (1) abundance, (2) packing (percentage of fossils per rock volume), (3) fragmentation, (4) articulation, (5) left/right valve proportion, (6) biofabric (original growth position, the lowest angle of the shells to the stratification surface and the concavity orientation), (7) preservation of the original mineralogy, (8) edge rounding and (9) biological interactions (encrustation and boring). All of these taphonomic signatures are tabulated as percentages. These values are then analyzed with a Q-mode cluster analysis for the definition of the taphofacies. Three taphofacies models are proposed: (1) outer-platform taphofacies, (2) biotic accumulations taphofacies and (3) inner-platform taphofacies. This study shows that, when more taphonomic attributes are used in the cluster analysis, the results are better and more robust.