A freshwater analog for the production of Epiphyton-like microfossils.

Authors:
Yadira Ibarra
Yadira Ibarra
1 Stanford University
Sonicah Sanon
Sonicah Sanon
San Francisco State University

Geobiology 2019 Apr 19. Epub 2019 Apr 19.

Department of Earth and Climate Sciences, San Francisco State University, San Francisco, California.

Calcified microbial microfossils-often interpreted as cyanobacteria-were important components of Precambrian and Paleozoic limestones, but their paucity in modern marine environments complicates our ability to make conclusive interpretations about their taxonomic affinity and geologic significance. Freshwater spring-associated limestones (e.g., travertine and tufa) serve as terrestrial analogs to investigate mineralization in and around aquatic biofilms on observable timescales. We document the diagenesis of calcite fabrics associated with the freshwater algae Oocardium stratum, an epiphytic colonial green algae (desmid) known for producing stalks of extracellular polymeric substances (EPS) and passively producing a bifurcating tubular calcite monocrystal. Bifurcating EPS stalks produced by Oocardium colonies can become calcified and preserved in ancient carbonate deposits. Calcified micritic EPS stalks have a filamentous morphology, show evidence of branching, and maintain uniformity in diameter thickness throughout the mm-scale colony, much like the enigmatic calcimicrobe Epiphyton. We provide a mechanism by which calcification associated with a colonial semispherical micro-organism produces microfossils that deceptively resemble filamentous forms. These findings have implications for the use of morphological traits when assigning taxonomic affinities to extinct microfossil groups and highlight the utility of calcifying freshwater modern environments to investigate microbial taphonomy.

Download full-text PDF

Source
https://onlinelibrary.wiley.com/doi/abs/10.1111/gbi.12341
Publisher Site
http://dx.doi.org/10.1111/gbi.12341DOI Listing
April 2019
2 Reads

Publication Analysis

Top Keywords

eps stalks
8
calcite fabrics
4
branching maintain
4
maintain uniformity
4
diagenesis calcite
4
uniformity diameter
4
fabrics associated
4
document diagenesis
4
evidence branching
4
filamentous morphology
4
oocardium stratum
4
algae oocardium
4
morphology evidence
4
diameter thickness
4
freshwater algae
4
associated freshwater
4
timescales document
4
calcimicrobe epiphyton
4
mineralization aquatic
4
investigate mineralization
4

References

(Supplied by CrossRef)
Hot spring siliceous stromatolites from Yellowstone National Park: Assessing growth rate and laminae formation
Berelson W. M. et al.
Geobiology 2011
Die Versteinerungen des cambrischen Schichten‐systems der Insel Sardinien nebst vergleichenden Untersuchungen uber analoge Vorkommnisse aus andern Landern
Bornemann J. G. et al.
Nova Acta Kaiser Leopold‐Carol Dtsch Acad Naturforsch 1886

Brasier M. D. et al.
2011

Similar Publications