PhD: Experimental and petrological insights into the preservation of Ediacaran matground communities

Summary

This project will use lab experiments to test hypotheses about the mechanisms involved in the exceptional preservation of Ediacaran microbial mats and associated macro-organisms in the fossil record.

Project background

The fossil record suggests that macroscopic organisms did not become diverse or widespread on Earth until ~570 Ma with the arrival of the impressive, diverse “Ediacaran biota”, which almost certainly included multicellular animals. Soft-bodied benthic Ediacaran macro-organisms are found as exceptionally well preserved fossils at several localities around the world, commonly associated with fossilized microbial mats that carpeted the seafloor and may have mediated fossilization. This project aims to combine taphonomic experiments with the study of fossil specimens (in collections) to advance debates surrounding the role of microbial activity and early diagenetic cementation in the preservation of Ediacaran macro-organisms and microbial mats, with implications for the affinities of these organisms, their tissue composition, mode of life, and their distribution across space and time.

Research questions

1. What was the biogeochemical activity of microbial mats associated with Ediacaran macro-organisms, and what was their role in fossil preservation?
2. How viable are the “early silicification” and “pyrite death mask” models for the preservation of Ediacaran soft-bodied organisms and matgrounds in relief on bedding planes within different facies represented at global fossil localities?
3. Can rapid cementation of sediment grains by pyrite, clay and/or silica be induced experimentally under realistic Ediacaran burial conditions?
4. Does early cementation lead to the formation of sediment moulds around soft tissues and microbial mats on experimental timescales?