The first whiffs of oxygen

Synopsis

The rise of molecular oxygen within the atmosphere and oceans of Earth represents a fundamental revolution in the chemistry of our planet – it gave rise to complex eukaryotic life. This rise is known as the Great Oxidation Event (GOE) and is believed to have occurred at 2.4-2.3 billion years ago (Ga). However, it was recently recognised that early whiffs of oxygen date back to 2.6 Ga. Therefore, making GOE a stepwise over a protracted period.

The project: “The First Whiffs of Oxygen” will investigate a new discovery of anhydrite (CaSO4) in 2.65 Ga rocks of the Hamersley Range, Western Australia. Anhydrite occurs in thinly bedded carbonate rocks that sit immediately beneath an impact-generated tsunami deposit, inferred to have been deposited in deep water. This anhydrite is the oldest known occurrence in the geological record. The presence of anhydrite points to the presence of free oxygen, but how it got in a deep water setting and its relationship to the impact deposit remains unknown.

The project will involve detailed mapping of the section containing the impact deposit and anhydrite crystals in Western Australia. Some detailed petrography and isotopic analyses of the carbonate rocks will also be required.

Aims

The primary aim of this project is to gain a better understanding of the occurrence of anhydrite in thinly bedded marine carbonates of the Hamersley Group. A secondary aim is to better understand the environment of deposition of the carbonate and associated rocks in this part of the Hamersley Basin.

Student benefits

During this project, you’ll get to tackle a world-first problem relating to the big questions of Astrobiology, including the evolution of life and the onset of the oxygenation of the atmosphere. This project will introduce you to issues relating to the deep time evolution of our planet and life on Earth, as well as to the community on campus made up of wonderful postgraduate students working on similar problems through time, and on Mars.

I work closely with my honours students because I’m always interested in their projects, so you’ll receive plenty of guidance, although I won’t spoon feed you. I have a very good track record of supervising students to first-class honours results.