Monday, October 31, 2005

Primordial Soupçon

Organic molecules formed in a “primordial womb”. Lynda Williams, Arizona State University, Department of Geological Sciences, Tempe, AZ 85287, USA; et al. Geology 33 (11): 913-916.

Expandable clay minerals can act like a primordial womb to protect and promote synthesis of organic molecules. On the early Earth, volcanic gases were emitted onto the seafloor from vents where carbon dioxide and hydrogen interact with metallic minerals to form methanol, a one carbon organic molecule. The temperature of this environment (>300°C [475°F]) would have been too high for most organic molecules to survive. However, clay minerals are commonly found in these volcanic vents, and expandable clay minerals (smectite), with silicate sheets stacked like a deck of cards, will adsorb and protect organics between the sheets. The clay mineral surfaces often promote organic reactions.

Williams et al. tested the potential for clays to not only protect methanol in hot water, but to synthesize new compounds needed as building blocks for more complex biomolecules. Volcanic vent simulations showed that certain expandable clays react quickly at 300°C to a non-expandable form, and the mineralogical changes coincide with production of a large number of complex organic molecules, primarily ring-structures (e.g., hexamethyl-benzene), some with up to 20 carbon atoms. The importance of this work is that it shows a potential mineralogical control on organic molecule evolution that could have been an important step in the origin of life.

Image from HERE.