PROCESS ICHNOLOGY: APPLICATION TO TRYPANITES-DEMARCATED DISCONTINUITIES

Process Ichnology is an approach to ichnological analysis that focuses on the interpretation of trace fossils as sedimentary structures, rather than as paleontological objects. The aim of Process Ichnology is to better assess and interpret physical and chemical (i.e. physico-chemical) depositional stresses in ancient sedimentary environments, such as salinity, oxygen level, turbidity and sedimentation rate. Process Ichnology has been applied to softground trace fossil assemblages, but has yet to be considered for hardground and firmground ichnological assemblages. Based on studies within modern settings, we propose that Process Ichnology observations can greatly contribute to the interpretation of sedimentary process associated with bored hardgrounds (Trypanites-demarcated discontinuities) in the rock record. These include: (1) depositional and erosional features resulting from heterogeneous distributions of hydraulic energy; (2) environmental parameters including water depth, salinity, the presence or absence of a sediment veneer, and hydraulic energy relating to biotic colonization time and distribution of borings; (3) evidence for renewed and multiple colonization events suggesting that colonization patters are complex and preserved bored hardgrounds do not only represent a snapshot in time; and (4) under optimal physico-chemical conditions, diverse assemblages of biota, including boring, encrusting and squatting organisms, are normally present. Currently, little effort has been made to correlate modern and ancient bored hardgrounds within the scope of Process Ichnology, and therefore it important to investigate features that can provide insight onto physico-chemical stresses associated with Trypanites-demarcated discontinuities.