Aquatic Sciences Meeting, Albuquerque 2001

SS43 Biogeochemical Processes in Stromatolites: A 3 b.y.old ecosystem (Spatial and Temporal Connections)

Date: Monday, February 12, 2001, Time: 2:15:00 PM

Location: Cimarron

Cady, S, L, Portland State University, Portland, USA, cadys@pdx.edu

Grotzinger, J, P, Massachusetts, Cambridge, USA, grotz@mit.edu

McKay, C, P, NASA Ames Research Center, Moffett Field, USA, mckay@galileo.arc.nasa.gov

Ford, D, C, McMaster University, Hamilton, Canada, dford@mcmail.cis.mcmaster.ca

MODERN FRESHWATER MICROBIALITES, PAVILION LAKE, BRITISH COLUMBIA, CANADA: GLIMPSES OF EARLY CAMBRIAN DENDRITIC REEF STRUCTURES EPIPHYTON AND GIRVANELLA

We recently reported a distinctive assemblage of freshwater calcite microbialites, some of which display microstructures similar to the fabrics displayed by Epiphyton and Girvanella, in Pavilion Lake, British Columbia, Canada (Nature, 2000, 407, 626-629). Epiphyton and Girvanella are a class of ancient calcareous structures that formed major Cambrain reefal belts together with Archeocyathids, stromatolites, and thrombolites. To a large extent, Middle to Late Cambrian reefs are quite similar to Precambrian reefs, with the exception that the latter, including terminal Proterozoic reefs, do not contain Epiphyton or Girvanella. The morphologies of the modern microbialites in Pavilion Lake vary with depth, and dendritic microstructures of the deep water (>30m) mounds indicate they may be modern analogs for the ancient calcareous structures. U/Th dating indicates the structures are less than 11,500 years old. We report here our efforts to determine how variations in the microbiological populations and fluctuations in lake water geochemistry influence the development and preservation of microbial biosignatures in these structures.

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Aquatic Sciences Meeting, Albuquerque 2001

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