New Mexico Geological Society Annual Spring Meeting — Abstracts

A series of mesothermal (~25 o C) mound springs located along the Tierra Amarilla (TA) anticline are related to a regional occurrence of CO2-rich travertine depositing springs in northcentral New Mexico. Previous work has shown that these springs exhibit geochemical (³He/⁴ He and CO₂/ ³He) evidence for the presence of endogenic fluids. We have hypothesized that CO₂- rich mound springs such as TA exhibit tectonic, geochemical, and microbiological similarities to marine vent systems. To assess the geochemistry and the metabolic reactions in these springs on a real-time basis, we deployed multi-parameter sondes at various depths in two springs on the axis of the anticline. Continuous measurements of pH, temperature, conductivity, dissolved oxygen, and depth were collected every five minutes for five days. The temperature and pH results indicate a weak diurnal signal at ~1 meter depth at the higher-discharge spring. The data from ~6 meter depth from the same spring displayed invariant temperature at ~26º C, pH 6, and anaerobic conditions. We use established protocols from studies for geochemical modeling to assess energetics in extreme environments. We use denaturing gradient gel electrophoresis (DGGE) to determine whether the mesothermal springs have similar species composition to hydrothermal vents. Environmental samples were collected on 0.22 micrometer Millipore Sterivex filters from several springs and preserved in sucrose lysis buffer. DGGE bands were sequenced from mud and filtered DNA extracts. These samples were found to be significantly similar to marine organisms (>94%). DNA was found to be 94% similar to Zetaproteobacteria that are also found in the deep-sea hydrothermal region of the East Lau Spreading Center and uncultured environmental bacterial samples collected from seamounts located along the Kermadec Arc (96% similarity). Algoriphagus sp. LYX05, an organism isolated from sediment along the coastal region of the Yellow Sea, was the closest relative to clones obtained from another spring (97% similarity). These data support the hypothesis that CO₂-rich springs in terrestrial extensional settings have similarities to marine vents and offer rich potential for linking mantle fluids to near-surface hydrochemistry and unique microbial niche