Microtaphofacies: Exploring the Potential for Taphonomic Analysis in Carbonates

Abstract

The microtaphofacies of Paleogene carbonates from three time units (Middle Eocene, Late Eocene and Early Oligocene) from the circumalpine area are described and compared. These carbonates are dominated by various larger foramin- iferal and coralline red algal facies with subordinate coral and bryozoan facies. The taphonomy of different components and the taphonomic attributes for each facies type are detailed using a semi-quantified scheme describing four different taphonomic features (abrasion, fragmentation, encrustation and bioerosion). This allows the distribution and magnitude of taphonomic features to be determined along the shelf gradient and between different time units. Taphonomic features vary between facies types and time units. Fragmentation, for example, is greatest in shallow water, inner shelf settings and is due to wave base water agitation. Abrasion and encrustation are variable throughout different facies whilst bioerosion varies through time. Middle Eocene facies are generally less taphonomically altered than the Late Eocene and Early Oligocene facies which seems to reflect the appearance of coralline algal dominated facies. The extinction events among larger foraminifera that dramatically influence the occurrence and distribution of facies have little effect on the distribution of taphonomic features.