Chemical evolution of the Proterozoic biosphere

Romain Guilbaud (University of Cambridge, UK)
September 12, 2016

ELSI-1 Building - 102 ELSI Hall (telecon)

During the past decade, the still emerging field of geobiology has witnessed major advances related to the interactions between the evolution of atmospheric oxygen, ocean chemistry, and biological innovation. These advances have revolutionized some views on the timing and the mechanisms of the Earth's surface evolution, opening an important range of unexplored research avenues. This is particularly true for the coevolution of oxygen availability and eukaryotes, from their emergence during the Proterozoic Eon (2500 to 541 million years ago, Ma) until the rise of animals, which marks the origins of our modern biosphere. A major issue which we are facing at the moment resides in the large uncertainties regarding ancient ocean oxygen levels, and we currently lack some of the very basic tools to identify low levels of oxygen in past water columns.

In this project, I will combine existing palaeoproxies to novel geochemical tools, in order to assess the links between eukaryote evolution and their chemical environment. Particular focus will be on the extent of ocean oxygenation around 2300 Ma; the reconstruction of low oxygen ('dysoxic') ocean conditions throughout the Proterozoic and their links with eukaryote evolution; the redox cycling of nutrients during the early colonisation of land by eukaryotes; and the architecture of the chemical environment at the dawn of animal radiation. This work will be highly multidisciplinary, evolving around organic and inorganic geochemistry (lipid biomarkers, speciation of Fe, U and P), traditional (C, S, O) and non-traditional (Fe, U) stable isotope systems, and palaeontology, allowing for a vast range of collaborations with international and ESLI experts in these fields.