Organic
Production by Iron Microbial Mats – Implications for Volcaniclastic
Successions and Hydrocarbons on Mars
Schieber, Juergen1
(1)
Study of microbial mats associated with a
ferrous iron producing freshwater spring reveals a highly productive mat
community. The mat is largely constructed from iron encrusted sheaths of Leptothrix spp., with variable
contributions of Gallionella spp.
stalks, and has an open framework texture. At a spring flow of between 5-10
m3/day the mat produces 5 mm daily growth over 15 m2. The TOC content of dried
mat can exceed 5 wt. %.
The heterotrophic sheathed bacterium Leptothrix produces most of the organic matter,
smaller contributions come from the autolithotrophic Gallionella. Several hundred grams of organic matter are
produced per day. Assuming fixation of 100 gC/day
yields a primary productivity of 2430g/m2yr, exceeding typical marine rates by
a factor of 25. Iron bacteria thrive over a wide range of salinities and
temperatures. Where abundant iron bearing fluids enter a basin, such as from
shallow marine freshwater springs, cold seeps, and deep sea
Iron microbes still thrive near submarine
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California