Matthew Dodd

"Following the traces of the oldest life on Earth."

PhD project title:

Biosignatures in Earth’s oldest sedimentary rocks.

Matthew Dodd

Project description:

The overarching goal of my research is to trace the origin of organic matter as a possible biosignature of early life on Earth. Studying traces of life in some of the oldest sedimentary rocks on Earth is challenging because of the possibility of natural contamination by young fluids in the crust and alteration minerals that may be similar to biologically-produced ones. If the organic matter is shown to not be indigenous or to be non-biological in origin, this will also be important because we need this benchmark in order to prepare for the analysis of samples from Mars, a planet where we do not yet know whether life ever existed. This quest to search for and understand our origins is also astrobiological in nature and can be seen as preparatory work to study future Mars Sample Return. 

The project involves the systematic study of organic matter in petrographic thin sections from a range of Precambrian sedimentary rocks such as banded iron formations, cherts and carbonates up to around 4 billion years old. A variety of micro-analytical tools are used to characterize the molecular, elemental, isotopic, and structural characteristics of the organic matter. A few examples of these instruments include: laser Raman micro-spectroscopy, Scanning and Transmission Electron Microscopy (SEM and TEM), Secondary Ion Mass Spectrometry (SIMS) and dual beam Focused Ion Beam – SEM (FIB).

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