Alison Olcott Marshall

Assistant Professor of  Paleobiogeochemistry


Currently, there are several ongoing research programs in the lab, and there are opportunities for students who are interested in working on any of them. Here is a snapshot of some of the work that is ongoing in my lab.

Precambrian (Archean and Proterozoic) Signs of Life

The Precambrian fossil record is sparse, composed mainly of enigmatic microfossils, carbon films and forms, and stromatolites, putative microbial mats.  While the morphology of all of these fossils is well studied, not much is known about the chemistry of these fossils and forms, a gap in knowledge my lab is trying to fill by using a combination of petrographic thin section work and chemical analyses.

Biomarker Preservation of Martian Analogs

Working in the Precambrian has revealed how difficult it can be to define the presence of life in the fossil record here on Earth, where we can walk right up to the rocks and collect as many samples as we can cram into a bag. The difficulties are likely to multiply in the search for life elsewhere, as currently all such explorations are remotely directed with limited chances to collected replicate analyses. We work in Mars analogous environments here on Earth to figure out how to collect and analyze samples on Mars, with the hopes to maximize the success of data collection by the rovers.

Stromatolite Formation and Preservation

Nearly 100 years after they were first described, the origin of stromatolites remain an enigma, as researchers are still unsure if these layered carbonates are always a sign of ancient life. This question becomes extra relevant as researchers are now looking for signs of stromatolites on Mars.

Burgess Shale Type Preservation

The Cambrian is marked by deposits containing exquisite soft bodied preservation, but it is unsure how this preservation occurred.  We are attempting to unravel the mystery by examining the mineralogy and extractable biomarkers of some of these fossils.

The Biosphere of Snowball Earth

There is a growing body of evidence that there were a series of extreme glaciations at the end of the Proterozoic, glaciations that may have covered most of the world in ice.  By examining organic-rich cores deposited during these glaciations, I hope to gain a better idea of what the biota in the ocean was like, and thus, by extension, what the oceans were like.

Biomarkers of the Devonian Extinction

While the Devonian contains one of the “Big Five” mass extinctions, not a lot is understood about the causes of that extinction.  We are analyzing the microfauna, geology, and lipid biomarkers of a site spanning the extinction, with the hope of understanding the ocean chemistry and biology across the extinction event.