Evidence for Fossilized Subsurface Microbial Communities at the TAG Hydrothermal Mound

Abstract

Scanning electron microscope examinations have revealed fossilized cell-like structures randomly distributed in near-surface oxidized deposits of red and gray Fe-rich chert and Fe-Si oxyhydroxides of the Trans-Atlantic Geotraverse (TAG) hydrothermal mound, Mid-Atlantic Ridge at 26°08'N. Chemically, these structures are carbon-based with the morphology of half-spheroids that are 2 to 3 w m in diameter and are mostly arranged in the form of clusters and long thread-like cellular masses that resemble single-celled microorganisms. The wide range of intracrystalline silica concentration, which seems to replace the original chemistry, suggests that the microorganisms were subjected to various degrees of silica mineralization, which was probably controlled by the thermal development of this hydrothermal site.

Keywords:

• Tag Hydrothermal Mound
• Fossilized Cell-LIKE Structures
• Silica Mineralization