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Thermal Features
Konhauser, Kurt

Dr. Kurt Konhauser

Research Professor
Department of Earth and Atmospheric Sciences
University of Alberta
Edmonton, T6G 2E3, Outside the U.S.
Current Research Interests Hot Spring Sinter Formation
It is now well established that there is a close association between the different types of hot spring sinter and the microorganisms growing in the overlying mat community. However, what remains lacking is a full understanding of how different microbial assemblages form the unique biosedimentary features (i.e., morphology, fabric) intrinsic to each sinter. Working on the hot springs at Krisuvik, Iceland, we examined in detail the columnar microstromatolites forming at temperatures between 30-40oC. Several important findings were made (Konhauser et al. 2001). First, we showed that cyanobacterial silicification contributed significantly to the overall sinter formation, with nearly 50% of the structure comprising biomineralized cells. Second, the microstromatolites were laminated, with the cyclicity related to seasonal variations in microbial activity. Third, recolonization of the solid silica surface occurred by free living bacteria: cell motility was not responsible for the laminations. Fourth, and most surprisingly, this work also demonstrated that insufficient light penetrates deep within the sinter to support photosynthesis, yet culturable populations of cyanobacteria were recovered. This meant that those cyanobacteria living in the deeper layers either changed their mode of metabolism, they became inactive or they no longer were the dominant microorganisms. Recent work in New Zealand has also shown that silicification in silica-supersaturated hot springs can be extremely rapid (on the order of hours to days) and that the microbes appear well preserved with their general morphology, diameter, length, and presence/absence of septa being readily apparent.  However, most of the silicified microbes lack any key features that would allow accurate comparisons with extant taxa. Moreover, the presence of collapsed filaments and pseudo-fossils complicate any efforts to relate the extant silicified cells to ancient microfossils (Jones et al., 2004; Jones et al., 2005).

I am now in the process of continuing this work in Yellowstone National Park, USA with Dr. Bill Inskeep (Montana State) to ascertain the microbial influences on both silica and iron hydroxide precipitation under varying geothermal conditions. Natural sinter and effluent samples have been collected to characterize the dominant microflora, their activities and their relative importance in constructing the various sinter fabrics via biomineralization and growth patterns. This work will be linked to current studies on the origins of laminations in Archean stromatolites and on the mechanisms responsible for the fossilization of Archean microbial mats.

  1. Aquificales in Yellowstone National Park
    Geothermal Biology and Geochemistry in YNP [TBI Text!], 2005