Research

My principal research interests lie in geochronology and the geochemical evolution of the Earth during pivotal times of change in the geological record. I use a novel blend of rhenium-osmium (Re-Os) geochronology in tandem with field-based geology, sedimentology and stratigraphy to address a range of fundamental research questions that require constraining the timing, rates and durations of geological processes. My current questions include deciphering the nature of Proterozoic ice ages, elucidating the rates of large-scale tectonic reorganizations, and constraining biogeochemical developments across multiple time scales. It is imperative to determine how time is recorded in rocks in order to correlate strata and isotope excursions on basinal and global scales. 


My current research projects are focused on exploring the geological record of how and why after more than a billion years of climatic tranquility the Earth experienced extreme ice ages in the Neoproterozoic. Because much is still unknown about how the Earth entered and exited Snowball Earth states, I have worked on obtaining geochronological and geochemical data from hallmark Neoproterozoic successions in Canada, USA, Mongolia and Africa to refine our understanding of Proterozoic Earth system evolution. As part of this work, I am developing the use of Os isotope chemostratigraphy to gain insights into the fluxes of radiogenic and unradiogenic Os in pre- and post-glacial environments and as a new chemostratigraphic correlation tool. By combining Re-Os geochronology with major and trace element geochemistry, my goal is to improve our comprehension of the evolution of continental margins during the Rodinia supercontinent break-up and better constrain the timing of the change from extensional to passive margin tectonics. I am also applying Os isotope geochemistry and biomarker data to discriminate between non-marine and marine environments, and to quantify the rates and durations of the transitions between the two; this is particularly useful for investigating environments in deep time when paleontological criteria are lacking.


Beyond the Proterozoic there is still much work to be done on Paleozoic sedimentary successions to better refine timescale boundaries. Key aims are to more precisely understand the rates and durations of adaptive radiations, extinctions and recoveries e.g., the Permo-Triassic extinction and to gain a deeper insight into how the Earth has evolved as a system. Future projects in this topic would involve the use of Re-Os geochronology, Os isotopes and other Platinum Group Elements (PGE) to better track variations in the mantle flux of these elements compared with the input of terrestrial and extraterrestrial sources.  

Recently I have begun to explore secular variations in seawater metal isotope compositions to investigate the drivers of Quaternary climate change. My current work involves a combination of Os isotope stratigraphy, microfossil and sedimentological analysis of soft-sediment cores from glaciated regions, with the goal of answering fundamental questions about the interactions between weathering, ice sheet dynamics and ocean currents. For example, what controls the feedbacks between the Greenland ice sheet and ocean currents in the Atlantic and Labrador Sea? Building on these studies will permit us to test and refine sedimentation reconstructions that are currently based on geomorphic evidence. This work has begun to shed light on the regional variations present in seawater Os isotope composition and residence time as well as the interactions between regional geology and oceanic currents.