2002 Annual Science Report
Arizona State University Reporting | JUL 2001 – JUN 2002
Organic Synthesis at High Temperatures
Our overall goal is to explore the potential for abiotic synthesis of organic molecules important to the origin of life under geologically realistic conditions of pressure, temperature and chemical composition.
We have demonstrated experimentally that hydrogen, carbon dioxide and water react in the presence of the mineral magnetite under seafloor hydrothermal conditions to form methanol, a significant organic precursor molecule, (Voglesonger, et al., 2001).
Building on kinetic studies of the conversion of smectite clay to illite (Williams, et al, 2001) we have begun experiments to follow the conversion of methanol to more complex organic molecules in the presence of smectite/illite clay. Initial results of that work are being presented in an invited talk at the 2002 Geochemical Society Goldschmidt Conference in Davos, Switzerland, in August 2002 (Williams, et al., 2002). We have found that in systems of smectite clay, methanol, ethanol and water at 1000 bars and 300°C, a rich variety of organic compounds are synthesized and the relative abundance of those compounds changes with reaction time over a four week period. The compounds identified include alkanes, branched phenyl compounds, bicyclic aromatics, and stearates.
We have shown that it is possible to control the reduction/oxidation conditions in our sulfide-free experimental systems using palladium-silver semi-permeable membranes to control hydrogen activity. We are in the process of installing those membranes in two of our experimental systems.
The internal structure of sulfide chimneys in seafloor systems may provide sites for concentrating pre-biotic organic molecules. The recent collection of a large, living chimney has provided excellent samples to examine microporosity. This is being done using synchrotron X-ray tomography. We have developed computational techniques allowing visualization of porosity with a resolution of about ten microns (Ashbridge, et. al., submitted, 2002). A second paper describing the results for the sulfide chimney will be submitted by the end of the summer (Ashbridge, et. al., in preparation).
We continue to develop analytical techniques based on optical fiber probes to allow chemical analysis of small volumes in an experimental apparatus for organic synthesis and in natural environments at hydrothermal conditions (Gentleman, et. al., 2001).
PROJECT MEMBERS:John Holloway
RELATED OBJECTIVES:Objective 1.0
Determine whether the atmosphere of the early Earth, hydrothermal systems or exogenous matter were significant sources of organic matter.