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Encyclopedia > Stromatolite
Pre-Cambrian stromatolites in the Siyeh Formation, Glacier National Park.
Pre-Cambrian stromatolites in the Siyeh Formation, Glacier National Park.

Stromatolites (from Greek strĊma, mattress, bed, stratum, and lithos, rock) are defined as "attached, lithified sedimentary growth structures, accretionary away from a point or limited surface of initiation". A variety of stromatolite morphologies exist including conical, stratiform, branching, domal, and columnar types. Stromatolites are commonly thought to have been formed by the trapping, binding, and cementation of sedimentary grains by microorganisms, especially cyanobacteria. However, very few ancient stromatolites actually contain fossilized microbes. While features of some stromatolites are suggestive of biological activity, others possess features that are more consistent with abiotic precipitation. Finding reliable ways to distinguish between biologically-formed and non-biological or "abiotic" stromatolites is an active area of research in geology. |Pre-Cambrian stromatolites in the Siyeh Formation, Glacier National Park File links The following pages link to this file: Evolution Origin of life Panspermia Stromatolite ... |Pre-Cambrian stromatolites in the Siyeh Formation, Glacier National Park File links The following pages link to this file: Evolution Origin of life Panspermia Stromatolite ... The Precambrian or Cryptozoic is the period of the geologic timescale from the formation of Earth around 4500 million years before the present (BP) to the evolution of abundant macroscopic hard-shelled fossils, which marked the beginning of the Cambrian, some 542 million years BP. Remarkably little is known about... Glacier National Park is a National Park in the U.S. state of Montana. ... Orders The taxonomy of the Cyanobacteria is currently under revision. ... A fossil Ammonite Fossils (from Latin fossus, literally having been dug up) are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history and the processes that shape it. ...


Stromatolites were more abundant on the Earth in Precambrian times. The Precambrian atmosphere was rich in carbon dioxide, but lacked the oxygen that sustains the complex multicellular life that has since evolved. Stromatolites in the geological record declined sharply in both diversity and number during the Paleozoic, and are uncommon in modern day marine environments. During the Precambrian, there were no burrowing or grazing animals to destabilize sediments and consume growing microbial mats - favoring the preservation of microbialites. During the Precambrian, changing chemical conditions in the ocean could be responsible for the precipitation of non-biological stromatolites through the growth of tiny crystals. The Precambrian is an informal name for the eons of the geologic timescale that came before the current Phanerozoic eon. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... A speculative phylogenetic tree of all living things, based on rRNA gene data, showing the separation of the three domains, bacteria, archaea, and eukaryotes. ... The Paleozoic is a major division of the geologic timescale, one of four geologic eras. ...

Modern stromatolites in Shark Bay, Western Australia.
Modern stromatolites in Shark Bay, Western Australia.

While prokaryotic cyanobacteria themselves reproduce asexually through cell division, they were instrumental in priming the environment for the evolution of more complex eukaryotic organisms. Cyanobacteria are thought to be responsible for increasing the amount of oxygen in earth's atmosphere through photosynthesis. Cyanobacteria use water, carbon dioxide, and sunlight to create food. The byproducts of this process are oxygen and calcium carbonate (lime). A layer of mucous often forms over mats of cyanobacterial cells. In modern microbial mats, debris from the surrounding habitat can become trapped within the mucous, which can be cemented together by the calcium carbonate to grow thin laminations of limestone. These laminations can accrete over time, resulting in the banded pattern common to stromatolites. The domal morphology of biological stromatolites is the result of the vertical growth necessary for the continued infiltration of sunlight to the organisms for photosynthesis. Image File history File links Download high resolution version (2440x1816, 1402 KB)Stromatolites growing in Shark Bay, Australia. ... Image File history File links Download high resolution version (2440x1816, 1402 KB)Stromatolites growing in Shark Bay, Australia. ... Shark Bay Shark Bay is a locality in the Gascoyne region of Western Australia. ... Motto: Cygnis Insignis (Distinguished by its swans) Nickname: Wildflower State Other Australian states and territories Capital Perth Government Governor Premier Const. ... Prokaryotes (from Old Greek pro- before + karyon nut, referring to the cell nucleus, + suffix -otos, pl. ... A speculative phylogenetic tree of all living things, based on rRNA gene data, showing the separation of the three domains, bacteria, archaea, and eukaryotes. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (also spelled eucaryote) is an organism with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Leaf. ... The word mucous is an adjective which means pertaining to mucus or having the qualities of mucus. ... Limey shale overlaid by limestone. ...


Modern stromatolites are mostly found in hypersaline lakes and marine lagoons where extreme conditions exclude animal grazing. An example of such a location is Shark Bay in Western Australia where excellent examples are found. Shark Bay Shark Bay is a locality in the Gascoyne region of Western Australia. ... Motto: Cygnis Insignis (Distinguished by its swans) Nickname: Wildflower State Other Australian states and territories Capital Perth Government Governor Premier Const. ...


Layered spherical growth structures similar to stromatolites are also known. They are called "oncolites".


Reference

Grotzinger and Knoll; Stromatolites in Precambrian Carbonates: Evolutionary Mileposts or Environmental Dipsticks? 1999.


  Results from FactBites:
 
Stromatolite - Wikipedia, the free encyclopedia (458 words)
Stromatolites are commonly thought to have been formed by the trapping, binding, and cementation of sedimentary grains by microorganisms, especially cyanobacteria.
Stromatolites in the geological record declined sharply in both diversity and number during the Paleozoic, and are uncommon in modern day marine environments.
The domal morphology of biological stromatolites is the result of the vertical growth necessary for the continued infiltration of sunlight to the organisms for photosynthesis.
Stromatolites (2119 words)
In many respects stromatolites are the most intriguing fossils that are our singular visual portal (except for phylogenetic determination of conserved nucleic acid sequences and molecular fossils) into deep time on earth, the emergence of life, and the eventual evolving of the beautiful life forms from Cambrian to modern time.
Stromatolites and their close cousins the thrombolites, are rock-like buildups of microbial mats that form in limestone- or dolostone-forming environments.
By normalizing stromatolite forms with volume of preserved carbonate rock, the authors posit that the steepest decline in stromatolite form diversity occured in the late Neoproterozoic, and culminated in the Lower Cambrian, coincident with the widespread appearance of macroscopic metazoa and significant bioturbation (i.e., activity of bottom-living animals that keeps sediments oxygenated and homogenous).
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