Sunday, November 19, 2006
The origin of life lies in unique ocean reefs, and scientists from the University of Miami's Rosenstiel School of Marine and Atmospheric Science have developed an approach to help investigate them better.
A new article published in the November issue of the journal Geology reveals how Dr. Miriam Andres' stromatolite investigation - the first of its kind - has begun to "fingerprint" ancient microbial pathways, increasing the understanding of how these reef-like structures form and offering a new way to explore the origins of these living records, which are considered to be the core of most living organisms.
Modern marine stromatolites are living examples of one of the earth's oldest and most persistent widespread ecosystems. Although rare today, these layered deposits of calcium carbonate are found in shallow marine seas throughout 3.4 billion-year-old geologic records. Ancient stromatolites represent a mineral record of carbonate chemistry and the evolution of early life.
Continued at "Origins of Life: New approach helps expand study of 'living fossils'"
Authigenic aragonite preserves a carbon isotopic record of heterotrophic microbial influences on dissolved inorganic carbon (DIC) in microenvironments within shallow subtidal stromatolites from Highborne Cay, Bahamas. A greater amount of aragonite precipitates when and where respiration, rather than photosynthesis, influences local DIC, which is consistent with sulfate reduction promoting carbonate precipitation and calcium release during decay of exopolymeric substances. Thus, heterotrophs play a more direct role than phototrophs in stromatolite lithification. Cyanobacteria are spatially associated with aragonite containing heterotrophic isotopic signatures. Hence, the absence of an autotrophic isotopic signature in the rock record does not imply the absence of photosynthetic organisms.
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