EPS Colloquium:
The Co-Evolution of Life & Earth’s Surface Environments

Abstract:

The Earth Surface System and life are intimately coupled and have been for much of the last 4-billion-years. Iron formations offer a key window through which we can examine the composition of the Archean to Paleoproterozoic ocean, the redox transition of the early atmosphere, and the diversification of the biosphere. Recent suggestions, however, have challenged the classical view that banded iron formation (BIF) was the result of ancient phytoplankton oxidizing dissolved ferrous iron. Through the use of a hydrogeological box model – as presented here – BIF depositional models can be evaluated within a quantitative framework that clearly demonstrate that these sediments were primarily ferric iron-containing, and that an active photosynthetic biosphere was already in place by at least 2.5 billion years ago. Additional examples of trace element chemistry in BIF and shales will also be presented highlighting how the chemistry of Earth’s surface environments are related to the evolution of life. These past, and current, research projects provide the basis for future research directions that will focus on understanding the cycling of elements in ancient environments, the development of novel proxies for tracking marine pH through time, and may be extended to the development of environmental remediation strategies.