Co-Evolution of Precambrian Life and the Environment

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Throughout Earth's history the availability of trace elements in seawater has been controlled by long-term geological processes, such as the gradual cooling of the upper mantle, changing styles of volcanism and continental composition, and the punctuated accumulation of atmospheric oxygen that fostered oxidative weathering reactions. The idea that these events may have directed microbial evolution at the enzymatic level over billions of years is relatively recent, but incredibly profound because microbiological innovations ultimately determined Earth's habitability for the more complex organisms that followed. Much of my current research programme is focused on resolving seawater composition in deep geological time, with an aim of better understanding of the co-evolution of Earth's Precambrian environment and biosphere. The basis for this research will be the coupling of field and laboratory studies. The field component consists of the collection and analyses of three contrasting marine sediments; (i) banded iron formations, (ii) black shales, and (iii) stromatolitic carbonates. Each lithology has individually been used with great success to decipher temporal variations in seawater composition. However, what has never been attempted before is an integration of datasets to provide a comprehensive picture of the paleo-nutrient landscape that, as today, should have varied along an ocean transect. I will focus on two specific time intervals: the (1) Eoarchean (4.0-3.7 Ga) when life first evolved, and (2) Neoarchean-Paleoproterozoic (2.7-2.3 Ga) when Earth first became oxygenated. The lab component will focus on designing experiments to compliment those field studies. Specifically, my goal is to (i) ascertain how ancient marine plankton survived in oceans with elevated metal concentrations and lethal influxes of ultraviolet radiation, (ii) use a combination of geochemical modelling, proteomics and genomics to elucidate the importance of bioactive metals in the origins of bacterial metallo-enzymes, and (iii) refine existing complexation models via synchrotron radiation techniques to determine the molecular mechanisms for trace metal uptake into primary BIF minerals and stromatolites in order to calibrate our rock record data.