1. Microbial sedimentology

In nature, life’s remains generally do not preserve for very long, rarely surpassing tens of thousands of years after death, because they are efficiently recycled by various processes. A very small fraction do preserve, in a format that what we call fossils which can last for millions of years or more. Our Earth is very old, formed some 4.6 billion years ago. The earlier back we examine in the rock record, the more difficult it is to find information about life. Still, life on Earth collectively left tracable records as far back as 3 billion years. In more then 80% of this history, the fossil record is dominated by tiny microorganisms while animals and plants are a rather recent phenomenon.

Fossil preservation depends on key transformations during which a more stable form of substance infiltrate, cast, stablize or replace the less stable original substance that life is made of. The presence of life may also induce environmental changes that are unique to the community’s characteristics and behaviors. These traces can also be preserved. Despite decades of research, the mechanim of fossil formation remain illusive, partly because the long durations that might be required to form them.

My research focuses on (1) understanding the mechanisms of cellular degradation, and (2) probing environmental forces that drive stable mineral formation around cells, while linking this to life’s core activities and metabolisms when the organism is alive, and when it is no longer alive while being degraded by other processes. This research can broadly guide us in the interpretation of fossil forms, and help us distinglish life from non-life forms in the rock record.

I take both laboratory experimental and field approaches to investigate the process of fossilization. Central to this research is to understand three kinds of common materials: amorphous silica, carbonate and silicate (clay) minerals that are very important at preserving morphological and chemical signatures of life. Instead of treating each mineral phases separately, I take an intergral approach realizing that prior to fossilization, the aqueous chemistry of metal cations and silicate, carbonate anions in solution play a crucial role. Therefore, I am heavily invested in efforts to develop efficient analytical and experimental tools that can help us track the solution chemistry during mineralization and fossilization. I hope to share in as much detail as I can how these tools are constructed and how experiments were conducted in the space of this website and in my publications.