Michelle Stevens

Michelle Stevens completed her BSc. in Earth Sciences at Carleton University (Canada) in 2024. While at Carleton she had the opportunity to work with Drs. Lyle Nelson and Peter Crockford on the Lomagundi-Jatuli Event (LJE) recorded in the Nash Fork Formation, Wyoming. The Nash Fork Formation records the highest δ¹³C values ever recorded in marine sediments (30‰) and has been leveraged as evidence for an ‘oxygen overshoot’. However, controversy remains regarding the local, global or diagenetic nature of this enigmatic geochemical feature. This research is now part of her MSc. supervised by Dr. Peter Crockford at Carleton University and Dr. Lyle Nelson at the Massachusetts Institute of Technology and aims to further decipher the depositional conditions of the Nash Fork Formation, combining petrology, minerology, and geochemical tools to decipher the local, global or diagenetic nature of the extreme δ¹³C values. Specifically, she is applying barium isotopes (δ¹³⁸Ba), and triple oxygen isotopes (Δ¹⁷O) in carbonate associated sulfate (CAS), as indicators of possible basin restriction, along with iodine-to-calcium ratios (I/Ca) and carbonate associated phosphate (CAP), to constrain the degree of water column oxygenation and nutrient levels respectively. These geochemical tools will aid in distinguishing between current GOE and LJE hypotheses and shed new light on the extremely positive carbon isotope values within the Nash Fork Fm. After completing her MSc. Michelle hopes to continue researching Proterozoic carbon cycling and explore implications on biospheric evolution.