The Huronian Supergroup in Ontario, Canada represents one of the most complete and representative sedimentary successions of early Paleoproterozoic age anywhere on Earth, yet we still have a limited understanding of its' absolute age, stratigraphy and environment of deposition. Within it, we find a record of 3 possibly global-scale glaciations and intervening periods of climatic amelioration as well as the earliest evidence for oxygenation of Earth's atmosphere.
Potential Research topics include:
- Characterization of the nature and timing of the "Great Oxidation Event" or GOE and to determine if this changeover was a single, irreversible event or an oscillatory or stepwise process taking place over 10s or 100s of millions of years. Recent isotopic work suggests that the changeover took place during deposition of the middle Huronian Supergroup, but the sedimentological evidence for oxidation (e.g., terrestrial red sandstones, ferruginous paleosols, and marine sulphate evaporite rocks), is much higher in the stratigraphic succession. If the GOE was abrupt, can it be linked to one of the 3 glaciations?
- Description and interpretation of the depositional environments of the sedimentary rocks that span the GOE time interval and determine whether they can be related to the atmospheric changeover. This study requires a search for conclusive sedimentological evidence of oxidation - in other words, clear evidence that oxidative reddening is early (pre-cementation) and occurs in rocks deposited in terrestrial environments. We would also like to understand the trigger(s) for deglaciation and climatic amelioration with a focus on the uppermost cycle (transition from the Gowganda Formation to the Lorrain Formation), which is well exposed in the Cobalt Basin.
- To determine the age and provenance of source detritus (U-Pb detrital zircon geochronology) in the Huronian basin, as a means of evaluating sedimentation pathways and tectonic models of basin development - can tectonic changes recorded in the Huronian basins be linked with the GOE? Geochronology would also include a search for zircon-bearing volcanic ash layers, which have been recently discovered in the upper Huronian Supergroup and used to date it and other possibly correlative stratigraphic units. This work will also contribute to the continuing debate on global-scale correlation of tectono-stratigraphic units such as the Transvaal Supergroup of South Africa and possible linkages between the GOE and "snowball Earth" glaciations.
Master's Degree in some aspect of clastic sedimentary geology with field experience, preferably working in remote wilderness areas.
Geochronology, inorganic geochemistry, isotope geochemistry, climatology and sedimentary petrography.
This research is funded by a Canadian Government NSERC Discovery Grant providing a yearly stipend that includes support for several weeks of summer fieldwork. Teaching assistantships and other scholarship opportunities available through the Dept. of Earth Sciences at Carleton University.
Robert Rainbird, firstname.lastname@example.org
Dr. Rainbird is a research scientist at the Geological Survey of Canada in Ottawa, Ontario and has been an adjunct professor in Carleton University's Earth Science Dept. for more than 20 years.