Proposal

Olivine hydration, also called serpentinization is a geochemical process resulting in the synthesis of molecular hydrogen. Hydrogen in the presence of carbon dioxide is then capable of producing methane. This natural production of hydrogen and methane occurs in a number of geological environments. This natural production of hydrogen may explain the origins of life on Earth and on other planets because hydrogen is capable of the sustenance of simple forms of life. The serpentinization of olivine is also a potential source of hydrogen that may be exploited as a new energy source if the rate of formation is high enough. The purpose of my off-campus research will be to study the rates at which serpentinization yields hydrogen and methane at elevated temperatures and pressures (similar to the environment in mid-ocean ridges and forearc environments), to be conducted at the U.S. Geological Survey space under the direction of Bob Rosenbaum in Menlo Park, CA, using flexible-gold cell technology. My research advisor's hypothesis is that the rate of hydrogen production increases with increasing temperatures and is independent of pressure (assuming a high pressure, 100- 500 bar) for average Earth olivines (Fo90). The second hypothesis is that methane production due to serpentinization is inhibited without a mineral catalyst such as chromite. The overall importance of this research will be to further understand the complex relationships of serpentinization reactions, in order to advance our current knowledge on the origins of life and to potentially find alternative fuel sources.

Summary

Kaitlynn Heflin
Experimental Geochemistry Lab Intern
Costal and Marine Geology Group
U.S. Geological Survey, Menlo Park, CA
Mentors: Bob Rosenbauer (USGS), Chris Oze (Bryn Mawr College)
Geochemical Processes

This summer I participated in geochemical research at the U.S. Geological Survey in Menlo Park, California. I worked under Bob Rosenbauer, a Senior Researcher at the U.S. Geological Survey, with Camille Jones, a Geology major at Bryn Mawr College. We focused on two topics of research that have a similar experimental setup, and sampled for both throughout the summer. The first topic of research is part of Bob's ongoing work at the U.S.G.S., and was on carbon dioxide sequestration by basalt and saltwater under 200 bars of pressure and at 100 degrees Celsius. This is relevant to the storage of carbon dioxide in deep brine formations in the sandstone of used oil wells. The second part of the research was about serpentinization and its production rates of hydrogen and methane at 300 bars of pressure and 200 degrees Celsius. This is part of Chris Oze's research, who is a professor at Bryn Mawr College. Throughout the summer we ran two experiments on serpentinization, and one on carbon sequestration.

The experimental materials we used to study hydrothermal water-rock interactions at increased pressure and temperature conditions included a pressure vessel full of pressure fluid, into which we placed a flexible gold reaction cell. By increasing the pressure of the pressure fluid, the gold reaction cell would warp and the pressure inside it would change as well. We then placed this pressure-controlled vessel into a temperature-controlled autoclave, which allowed us to raise the temperature of the experiment up to 100 and 200 degrees Celsius.

The two experiments involving olivine included the following starting reagents: for experiment 1, olivine and synthetic seawater; for experiment 2, olivine, synthetic seawater, sodium bicarbonate, and chromite. The experiment about carbon dioxide included: basalt, sodium chloride, and carbon dioxide.

Periodic sampling of the experiments was then done to test for pH, refractive index, methane and hydrogen content, cations, and carbon. At the end of the experiment, we examined the samples using SEM, and will use XRD to further characterize the solids. EM was used at the beginning of the experiment to ensure that initial reactants were indeed olivine.

The experiments did not go as predicted, and so there is no conclusion as of yet. It will take more data analysis and research to discover what may have occurred in the reaction vessels.

This experience was useful in showing me the daily activities of a geochemical research scientist. I got a good feel for what a career in this field would be like, as far as what they do, and how much time they spend on which aspects of their job. I also learned how exciting lab work can be.