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  • Miocene Lacustrine Stromatolite


    Images:

    DPS Ammonite

    Taxonomy

    Stromatolite

    Kingdom: Bacteria
    Phylum: Cyanobacteria
    Class: N/A
    Order: N/A
    Family: N/A
    Genus: N/A
    Species: N/A
    Author Citation Stanier 1974

    Geological Time Scale

    Eon: Phanerozoic
    Era: Cenozoic
    Period: Neogene
    Sub Period: None
    Epoch: Miocene

    Stratigraphy

    Chalk Canyon Formation?

    Provenance

    Collector: DPS Ammonite
    Acquired by: Field Collection

    Dimensions

    Length: 9 "

    Location

    Carefree
    Maricopa County
    Arizona
    United States

    Comments

    This silicified lacustrine Miocene stromatolite is a trace fossil made by a gram-negative photosynthetic blue-green bacteria. The originally limestone stromatolite was formed as a bacterial mat trapped sediment and precipitated limestone as it grew from the lake floor towards the sun. It shows classic convex layering towards the top.

     

    The stromatolites occur in tuffaceous and lime rich lake sediments that might be part of the Chalk Canyon Formation that is bounded on the bottom by basaltic lava and volcanic rich conglomerate and sandstone on the top. Locally numerous silicified casts and molds of reed like plants, their roots, and palm wood occur in the lacustrine sediments. Since the area is under possible scientific investigation I will not give a more specific locality. The Arizona Museum of Natural History has fossils from the site per my showing them the site.

     

    The taxonomy is very unsettled as is the author of Cyanobacteria. Taxonomy per International Registry of Marine and Nonmarine Genera:

     

    https://www.irmng.org/aphia.php?p=taxdetails&id=110


    See also:

     

    https://link.springer.com/article/10.1007/s10750-014-1971-9

    “The cyanobacteria are named under Botanical and Bacteriological Codes, and the usage of both systems at the same time causes considerable confusion as the rules of the Botanical Code are quite different from those of the Bacteriological one.” 


    Photo 1: detail of photo 2.

     

    Photo 2: 9” wide polished cross section cut and polished courtesy of Stan Celestian.

     

    Photo 3: 6” wide polished cross section of another side.

     

    Photo 4: top of colony.

     

    Photo 5: bottom of colony. 
     

    Fossil Cyanobacteria & stromatolite overview:

    https://ucmp.berkeley.edu/bacteria/cyanofr.html

     

    Interesting paper that suggest Cyanobacteria created calcified structures because of interactions with viruses:

     

    White, R. A., 3rd, Visscher, P. T., & Burns, B. P. (2021). Between a Rock and a Soft Place: The Role of Viruses in Lithification of Modern Microbial Mats. Trends in microbiology, 29(3), 204–213. https://doi.org/10.1016/j.tim.2020.06.004

     

    https://newsroom.unsw.edu.au/news/science-tech/stromatolites-–-fossils-earliest-life-earth-–-may-owe-existence-viruses



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