Glauconite: An untapped archive recording the timing, pace and triggers of the Cambrian Radiation
Short description
The transition across the Ediacaran-Cambrian boundary heralds the origin and remarkable evolutionary radiation of complex animals, and was accompanied by major environmental change. The evolutionary significance of this key bioevent has long been intensely studied. However, the patchy occurrence and poor age control of suitable proxy archives mean that it has not been possible to precisely identify the timing of key evolutionary events, nor to conclusively evaluate potential environmental triggers. The overall goal of this project is to resolve this fundamental research gap using a previously overlooked, directly dateable palaeo-environmental archive – glauconite, a class of common marine authigenic clay minerals that records seawater chemistry.
Our approach
In this project, our approach leverages new technology and the stratigraphic abundance of glauconite to:
i) produce a precisely dated (new in-situ Rb-Sr technique) chronostratigraphic framework for late Ediacaran toCambrian sequences in Australia and China; and
ii) to generate a detailed, multiproxy metal isotope record of marine redox and continental weathering conditions over the Ediacaran to Cambrian periods (from micro-drilled glauconite grains).
The results of this research will
1) provide previously unobtainable constraints on the timing and rates of bilaterian
animal diversification, and
2) allow a critical assessment of the cause-effect relationships between commonly
hypothesised environmental triggers (weathering vs redox) and the origin of the Cambrian Radiation.
