So, what do you do when you start college in a pandemic and want to get involved in research? Julian Nosarzewski is a sophomore undergraduate who is majoring in geology, minoring in Portuguese, and has a deep interest in the evolution of life and environments on Earth. But with most labs locked down last year, Julian had to get creative in his undergraduate research, and he took a deep dive into learning about life and environments in the Precambrian with Linda Kah, Kenneth G. Walker Associate Professor of Carbonate Sedimentology and Geochemistry. Specifically, Julian has been delving into the world of stromatolites.
When we think of stromatolites (fossil microbial structures), we most commonly envision domal to columnar laminated features that occur in modern environments Shark Bay, Western Australia, and throughout the geologic record. But how do you explain microbial columns that are inclined—sometimes more than 30° from vertical—or even sinusoidal in their structure? With Professor Kah’s guidance, Julian began to think about stromatolites in terms of their individual layers. If the main layers of a stromatolite represent the microbial community that colonized the stromatolite surface at any one time, then successive laminae could really be considered snapshots of the interaction between the microbial surface and the sedimentary substrate through time. Just before the pandemic started, Kah had been in the field looking at stromatolites in 1 billion-year-old rocks of central India (Chandi Formation, Chhattisgarh Basin). Julian took the pictures of some particularly unusual, inclined stromatolites and began tracing lamination. In the spring of 2021, Julian presented his work at UT’s undergraduate research competition, EUREKA, and showed how individual beds of inclined stromatolites could be attributed, in some cases, to post-construction toppling, and in other cases, to the successive migration of stromatolitic laminae, possibly in response to long-shore currents. Julian continued his work, adding more complex inclined columns of the 1.4 billion-year-old Altyn Formation, Montana, to his analysis. And, with the reopening of lab spaces, Julian is adding some petrographic analysis to his research repertoire, exploring whether changes in composition of the sandy dolomite associated with the Altyn stromatolites may give clues to why the columns change orientations. Results of this combined project were presented by Julian at the GSA annual conference.