Investigating the origin of organic matter in hydrothermal systems of the Archean

Zepeda, Vanessa1

1Queensland University Of Technology, South Brisbane, Australia

The origin of organic matter from the 3.43 billion-year-old Strelley Pool Formation (SPF), Pilbara Craton, Western Australia has been heavily debated. The region has an extensive history of diverse hydrothermalism induced by thrusting granitoid complexes which underlie the protocontinent. In consequence, hundreds of siliceous chert dike systems rich in carbonaceous material cross-cut Archean sedimentary rocks. Hydrothermal systems have the potential to synthesize organic molecules abiotically by a process called Fischer Tropsch Synthesis, particularly in the presence of certain metal catalysts. Conversely, a recently proposed hydrothermal pump hypothesis suggests that organic matter in anoxic waters could have been incorporated and redistributed to significant depths due to the higher geothermal gradients in hydrothermal systems. Differentiating between abiotic and biological sources becomes increasingly difficult because both processes induce fractionation effects on 13C that are significantly depleted. The author aims to address the questions regarding the origin of organic matter in the SPF by exploring the distribution of metal catalysts that could stimulate abiotic synthesis, as well as utilizing fine-scale geological and geochemical techniques to form paleoenvironmental interpretations of the ancient hydrothermal system. Developing new investigative methods and corroborative lines of evidence from ancient systems like the SPF is likely to yield new insights into the origin and early evolution of life on Earth, as well as other bodies in our solar system such as Mars.


Vanessa was born in Arizona and moved to Hawaii for her bachelors and masters degrees. She completed two internships at the Jet Propulsion Laboratory where she worked with molecular biosignatures preserved in rocks. During this internship she was introduced to Dr. David Flannery and applied to QUT for her PhD.

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