Leeds Centre for Crystallization

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PhD positions

Chemical records of early Earth evolution: Trace-element scavenging by iron minerals in banded iron formations

Caroline Peacock, Liane G. Benning, Sam Shaw, and Simon Poulton (School of Earth and Environment)

Trace-element concentrations and isotopic profiles measured in geologic deposits have great potential for understanding and interpreting Earth history. Marine ferromanganese crusts, for example, might record aspects of ocean chemistry that help us reconstruct Earth’s key biogeochemical cycles over the last 70 million years. On the other hand, Banded Iron Formations (BIF) are much older, potentially holding an archive of chemical information related to the geochemistry of the Precambrian oceans and some of the key developments in Earth’s early biogeochemical evolution. In particular, nickel (Ni) concentration profiles in BIF have recently been used to help understand the onset of the Great Oxidation Event some 2.4 billion years ago.

In this project we will 1) investigate how geo-relevant trace-metals, including Ni and Mo, are taken up by authigenic BIF iron minerals at experimental conditions approaching those of the Precambrian ocean; 2) investigate what happens when authigenic metal-doped BIF iron minerals diagenetically transform; 3) use our lab data to generate parameters that quantitatively describe trace-metal uptake; and 4) use our parameters to help constrain Precambrian ocean chemistry and help interpret chemical signatures recorded in natural BIF. 

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