Pacific Centre for Isotopic and Geochemical Research
Department of Earth, Ocean and Atmospheric Sciences,
The University of British Columbia

PCIGR’s Matthijs Smit and Universität Bern Researcher Discover Possible Link Between the Evolution of Earth’s Curst and the Emergence of the Oxygen Cycle

Smit original
Matthijs Smit examines ancient rocks from the deep crust in Norway during the summer of 2017.

Researchers Matthijs A. Smit (PCIGR, UBC EOAS) and Klaus Mezger (Universität Bern, Switzerland) have discovered a possible link between the long-term evolution of Earth’s crust and the emergence of Earth’s oxygen cycle 3.0 billion years ago. Their findings have been published in Nature Geoscience.

Cyanobacteria may have produced O2 as early as 3.7 billion years ago. Still, it took almost a billion years for that O2 to start accumulating in the shallow oceans and, subsequently, the atmosphere during a period commonly called the Great Oxidation Event (2.4-2.2 Gyr ago). The slow and stepwise rise of O2 in Earth’s atmosphere has always been somewhat of a mystery. Links to the changing composition of continents at the time have been proposed. However, with clear constraints on the average composition of the continents lacking, these links have been difficult to elucidate.

Smit and Mezger decided to approach this problem by letting nature do the sampling. They analyzed the Cr/U chemistry of land-sourced sediments, working from the idea that these rocks sample large areas of the exposed continents and thus may provide a good representation of their average composition.

Their research revealed a staggering change in continental composition between 3.0-2.4 billion years ago. Before this period, the continents were much more rich in Mg and poorer in Si than today, and contained Mg-rich minerals such as olivine. Present-day analogues show that hydration of such mafic crust causes local surface waters to have extremely high pH and high concentrations of O2 scavengers such as methane and dihydrogen. Although rare today, such reducing waters must have been common before 3.0 Gyr ago. Ultimately, it may have been the removal of Earth’s primitive proto-continents and the cleansing of the environment from O2 scavengers, which set System Earth on track towards having an oxygenated and habitable environment conducive to the evolution of higher life forms.

The findings are among the first reported from a new interdisciplinary research program on the formation and evolution of Earth’s earliest continents. In this program, lead-PI Smit and his students use the world-leading analytical facilities at PCIGR to analyze relics of Archean continental crust found in Canada, Greenland, India, South Africa and elsewhere.

For more info, please see the Nature Geoscience article and the UBC News release.

Canada’s Minister of Defence Visits PCIGR

PCIGR was pleased to host the Canadian Minister of National Defence, Harjit Sajjan, for a tour of our nUBC facility on September 8, 2017. The Minister was on campus on behalf of the Minister of Science, Kirsty Duncan, to announce more than $42 million in funding to support fundamental research at UBC through the NSERC 2017 competition for the Discovery Grants program, scholarships, and fellowships. CFI and BC-KDF grants supported the construction of the PCIGR laboratory facilities and a recent NSERC RTI grant contributes to its ongoing operations.

The Minister with the PCIGR team. Front row (left to right): M. Amini, E. Megyeri-Lawless, A. Fourny, H. Sajjan, D. Weis, G. Murphy, M. Li. Back row: K. Smith, B. Kieffer, R. McMillan, J. Cutts, K. Gordon, V. Lai (photo credit: Paul Joseph)

The nUBC laboratory is classified as a clean room, a very specialized environment designed to reduce contamination. Because contamination can be brought in by people and their clothing, everyone entering the lab was required follow a strict gowning protocol.

Professor Dominique Weis describes the instruments at nUBC (photo credit: Paul Joseph)

The tour was led by PCIGR Director, Professor Dominique Weis, with assistance from her unique team of research staff and graduate students. The Honourable Minister was accompanied by Professor Gail Murphy, UBC Vice-President Research, and Enikö Megyeri-Lawless, NSERC Director of Research Grants, Engineering and Life Sciences. Many of the features and instruments in the lab were showcased, with a focus on the Nu1700 high-resolution multi-collector ICP-MS. The first of its kind in Canada, this instrument is particularly special due to its large size and specialized components, including a >4-tonne magnet. Of particular interest to the Minister, it is the same type of instrument used in the military to analyze sources of uranium (depleted or enriched).

The Nu1700 high-resolution multi-collector ICP-MS (photo credit: Paul Joseph)

Another highlight of the tour was the RESOlution M-50-LR, operated by PCIGR research associate, Dr. Marghaleray Amini. The instrument is a laser ablation system, coupled to an ICP-MS, which can ablate a wide range of geological and environmental materials at high resolution and low absorbance. Near the end of the tour, PCIGR graduate students Rhy McMillan, Kate Smith, Jamie Cutts, and Anais Fourny, and postdoctoral fellow Miling Li, had the opportunity to briefly explain their research to the Minister. Their projects speak to the great diversity of research that is enabled by PCIGR’s instruments and staff.

In conclusion, the tour was a great opportunity to showcase why PCIGR is a world-class geochemical facility. Thank you to the Minister and to everyone who joined us! For a detailed photographic report of the event from UBC photographer Paul Joseph, see the UBC Public Affairs album.