Brennan O'Connell

Earth's sedimentary systems have changed through time. I am a sedimentologist interested in uncovering the processes that shape paleoenvironmental change and influence sedimentary environments through the Precambrian and early Paleozoic. I am most interested in how Earth's sedimentary systems, marine oxygen levels, and life (microbes, animals, and plants) have co-evolved through time. To investigate possible links between variables I integrate sedimentology, stratigraphy, geobiology, and geochemistry in my research.

2025–now: Leverhulme Early Career Postdoctoral Fellow, University of Cambridge. My research examines tidal environments and vegetated coastlines before angiosperms.

2022–2025: Postdoctoral Research Associate, University of Cambridge. I am working with Alex Liu to constrain the sedimentology and stratigraphy of the Nama Group in Namibia to place paleoenvironmental constraints on Ediacaran macrobiota and a late-Ediacaran mass extinction.

2018–2022: PhD in Earth Science, University of Melbourne. I worked with Malcolm Wallace and Ashleigh Hood to explore the sedimentology of Neoproterozoic reefal systems, nearshore tidal environments, and the redox history of terminal Precambrian oceans. 

2016–2018: Research Associate, Yale University. I worked with Noah Planavsky to explore the chemical evolution of Earth's ocean-atmosphere using metal isotopes (Fe, Mo, Cr, U), trace metals, sedimentology, and petrography. 

2013–2016: MSc in Earth Science, University of Oregon. I worked with Rebecca Dorsey to investigate mixed carbonate-siliciclastic tidal sedimentation in the Miocene-Pliocene paleo-Gulf of California. 

2009–2012: BA in Geology, Colorado College.