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Approximate growth rates of early Proterozoic microstromatolites as deduced by biomass productivity

William P. Lanier
Approximate growth rates of early Proterozoic microstromatolites as deduced by biomass productivity
Palaios (December 1986) 1 (6): 525-542


An assemblage of microstromatolites and intraclastic stromatolitic fragments has been found in early carbonate-replacement black chert from a drill core (356 m) in the 2.3 Ga Transvaal Supergroup, South Africa. Unfragmented microstromatolite forms include columns, bulbous forms, and nodular forms--an assemblage representing nearly all of the basic macrostromatolite growth forms. The Transvaal materials are characterized by two predominant populations of fossilized microorganisms. Unicellular coccoid microfossils are preserved as patchy cell accumulations of up to 2.4 X 10 (super 9) /cm (super 3) (normalized densities at the surfaces of many microstromatolites). Rod- and vibrio-shaped bacterial microfossils occur in normalized densities of up to 1.3 X 10 (super 10) cells/cm (super 3) as stratified layers within many microstromatolites and stromatolite intraclasts. The bacterial layers are often (but not exclusively) found beneath dense surficial coccoid layers. Minimum microstromatolite growth rates have been estimated by assuming a steady-state model for stromatolite accretion, wherein a given amount of organic carbon (as determined by calculating the fossilized biomass of the coccoid cell layers) is converted to bacterial biomass within the bacterial layers. The rate of bacterial biomass turnover (biomass productivity) is calculated by measuring the frequency of fossilized dividing bacterial cells (FFDBC). In the steady-state model, bacterial biomass productivity is assumed to be proportional to microstromatolite accretion rates. Minimum growth rates as deduced by the FFDBC method range from 2-40 mu m/day. An average lamination thickness of 27mu m suggests that individual laminae may represent daily-growth markers. This study underscores the potential application of modern concepts of microbial ecology to fossilized microbial ecosystems (stromatolites).

ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 1
Serial Issue: 6
Title: Approximate growth rates of early Proterozoic microstromatolites as deduced by biomass productivity
Author(s): Lanier, William P.
Affiliation: Oberlin Coll., Dep. Geol., Oberlin, OH, United States
Pages: 525-542
Published: 198612
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 45
Accession Number: 1987-045671
Categories: StratigraphyPaleobotany
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, strat. cols., sketch maps
S35°00'00" - S22°00'00", E16°00'00" - E33°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 1987
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