BENISON, KATHLEEN COUNTER, and TINA PHILLIPS
Geology Dept., Central Michigan University, Mt. Pleasant, MI

Abstract: Possible Acidophilic Bacteria Trapped in Permian Halite

Unusual organic bodies found in the Permian Opeche Shale halite of North Dakota are closely associated with both sulfate minerals and extremely acidic fluid inclusions. These "hairy blobs" may possibly be the remains of bacteria that thrived in acid lake waters and promoted sulfate mineral growth.

Hairy blobs fit the criteria for bacteria. They are dark spherules with radiating acicular structures, or "hairs". The spherule cores and hairs are interpreted as organic because they show the Raman spectral character of disordered graphite. These bodies, including both the spherical cores and their radiating hairs, range in size from 0.1 - 2 mm. Some are isolated; others are found clustered together in groups. The hairs are straight with the exception of some kinks. Most hairy blobs are solid inclusions in chevron halite crystals, but some are trapped within fluid inclusions. Hairy blobs are closely associated with extremely acidic (pH<l as documented by laser Raman microprobe analyses) fluid inclusions, indicating that they lived in a hostile environment At the outermost end of some of the hairs are tiny (10s of micrometers) subspherical, clear beads of anhydrite and unidentified sulfate minerals. There are also halos of sulfate minerals partially surrounding some of these hairy blobs. This suggests that these organisms influenced the geochemistry and mineralogy of these Permian lake waters.

This may be the first documentation of ancient acidophilic bacteria. Further studies may give new insights on bacterially-mediated mineral crystallization in extreme environments of the past.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas