Stromatolite#Modern occurrence

{{short description|Layered sedimentary structure formed by the growth of bacteria or algae}}

File:Stromatolithe Paléoarchéen - MNHT.PAL.2009.10.1.jpg chert, about 3.4 billion years old,{{cite journal |title=A Rare Glimpse of Paleoarchean Life: Geobiology of an Exceptionally Preserved Microbial Mat Facies from the 3.4 Ga Strelley Pool Formation, Western Australia |first1=J-P.|last1=Duda |first2=M.J.|last2=Van Kranendonk |first3=V.|last3=Thiel |first4=D.|last4=Ionescu |first5=H.|last5=Strauss |first6=N.|last6=Schäfer |first7=J.|last7=Reitner |journal=PLOS One |year=2016 |volume=11 |issue=1 |pages=e0147629 |doi=10.1371/journal.pone.0147629 |pmid=26807732 |pmc=4726515 |bibcode=2016PLoSO..1147629D |doi-access=free}} from Pilbara Craton, Western Australia]]

File:Stromatolites in Sharkbay.jpg, Western Australia]]

Stromatolites ({{IPAc-en|s|t|r|oʊ|ˈ|m|æ|t|ə|ˌ|l|aɪ|t|s|,_|s|t|r|ə|-}} {{respell|stroh|MAT|ə|lytes|,_|strə|-}}){{refn|{{cite Merriam-Webster|stromatolite|access-date=2016-01-21}}}}{{refn|{{Cite dictionary |url=http://www.lexico.com/definition/stromatolite |archive-url=https://web.archive.org/web/20200617051951/https://www.lexico.com/definition/stromatolite |url-status=dead |archive-date=2020-06-17 |title=stromatolite |dictionary=Lexico UK English Dictionary |publisher=Oxford University Press}} }} or stromatoliths ({{etymology|grc|{{wikt-lang|grc|στρῶμα}} ({{grc-transl|στρῶμα}}), GEN {{lang|grc|στρώματος}} ({{grc-transl|στρώματος}})|layer, stratum||{{wikt-lang|grc|λίθος}} ({{grc-transl|λίθος}})|rock}}){{LSJ|strw{{=}}ma|στρῶμα}}, {{LSJ|li/qos|λίθος|ref}}. are layered sedimentary formations (microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). These microorganisms produce adhesive compounds that cement sand and other rocky materials to form mineral "microbial mats". In turn, these mats build up layer by layer, growing gradually over time.{{cite web |url=https://www.whoi.edu/oceanus/feature/what-doomed-the-stromatolites/ |title=What Doomed the Stromatolites? |last=Winner |first=Cherie |date=November 15, 2013 |publisher=Woods Hole Oceanographic Institution}}{{cite web |url=https://www.sciencedaily.com/releases/2008/07/080704122847.htm |title=Two-ton, 500 Million-year-old Fossil Of Stromatolite Discovered In Virginia, U.S. |date=July 8, 2008 }}

This process generates the characteristic lamination of stromatolites, a feature that is hard to interpret, in terms of its temporal and environmental significance.{{Citation |last=Seong-Joo |first=Lee |title=On Stromatolite Lamination |date=2000 |work=Microbial Sediments |pages=16–24 |editor-last=Riding |editor-first=Robert E. |url=http://link.springer.com/10.1007/978-3-662-04036-2_3 |access-date=2024-02-09 |place=Berlin, Heidelberg |publisher=Springer Berlin Heidelberg |language=en |doi=10.1007/978-3-662-04036-2_3 |isbn=978-3-642-08275-7 |last2=Browne |first2=Kathleen M. |last3=Golubic |first3=Stjepko |editor2-last=Awramik |editor2-first=Stanley M.|url-access=subscription }}{{Cite journal |last=Arenas |first=Concha |last2=Jones |first2=Brian |date=October 2017 |editor-last=Hollis |editor-first=Cathy |title=Temporal and environmental significance of microbial lamination: Insights from Recent fluvial stromatolites in the River Piedra, Spain |url=https://onlinelibrary.wiley.com/doi/10.1111/sed.12365 |journal=Sedimentology |language=en |volume=64 |issue=6 |pages=1597–1629 |doi=10.1111/sed.12365 |issn=0037-0746}} Different styles of stromatolite lamination have been described,{{Citation |last=Monty |first=C.L.V. |title=Chapter 5.1 The Origin and Development of Cryptalgal Fabrics |date=1976 |work=Developments in Sedimentology |volume=20 |pages=193–249 |url=https://linkinghub.elsevier.com/retrieve/pii/S0070457108711373 |access-date=2024-02-09 |publisher=Elsevier |language=en |doi=10.1016/s0070-4571(08)71137-3 |isbn=978-0-444-41376-5|url-access=subscription }}{{Cite journal |last=Suarez-Gonzalez |first=Pablo |last2=Quijada |first2=I. Emma |last3=Benito |first3=M. Isabel |last4=Mas |first4=Ramón |last5=Merinero |first5=Raúl |last6=Riding |first6=Robert |date=March 2014 |title=Origin and significance of lamination in Lower Cretaceous stromatolites and proposal for a quantitative approach |url=https://linkinghub.elsevier.com/retrieve/pii/S0037073813002066 |journal=Sedimentary Geology |language=en |volume=300 |pages=11–27 |doi=10.1016/j.sedgeo.2013.11.003}} which can be studied through microscopic and mathematical methods. A stromatolite may grow to a meter or more.{{cite web |url=http://www.indiana.edu/~geol105b/images/gaia_chapter_10/stromatolites.htm |title=Stromatolites |publisher=Indiana University Bloomington |access-date=14 May 2018 |archive-date=19 March 2018 |archive-url=https://web.archive.org/web/20180319165624/http://www.indiana.edu/~geol105b/images/gaia_chapter_10/stromatolites.htm |url-status=bot: unknown}}{{cite journal |last=Riding |year=2007 |first=R. |title=The term stromatolite: towards an essential definition |journal=Lethaia |volume=32 |issue=4 |pages=321–30 |url=http://www3.interscience.wiley.com/journal/119935443/abstract |archive-url=https://archive.today/20150502101712/http://www3.interscience.wiley.com/journal/119935443/abstract |url-status=dead |archive-date=2015-05-02 |doi=10.1111/j.1502-3931.1999.tb00550.x|url-access=subscription }} Fossilized stromatolites provide important records of some of the most ancient life. As of the Holocene, living forms are rare.

Definition

File:Paleoproterozoic stromatolites oncoids Franceville.jpg

Stromatolites are layered, biochemical, accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains in biofilms (specifically microbial mats), through the action of certain microbial lifeforms, especially cyanobacteria.

Ancient stromatolites

File:SoegininaStromatolitesEstonia.jpg (Paadla Formation, Ludlow, Silurian) near Kübassaare, Estonia]]

=Morphology=

Fossilized stromatolites exhibit a variety of forms and structures, or morphologies, including conical, stratiform, domal, columnar,{{cite journal |last1=Zhu |first1=Dongya |last2=Liu |first2=Quanyou |last3=Wang |first3=Jingbin |last4=Ding |first4=Qian |last5=He |first5=Zhiliang |title=Stable carbon and oxygen isotope data of Late Ediacaran stromatolites from a hypersaline environment in the Tarim Basin (NW China) and their reservoir potential |journal=Facies |date=July 2021 |volume=67 |issue=3 |pages=25 |doi=10.1007/s10347-021-00633-0|s2cid=235638690 }} and branching types.{{cite journal |last1=Planavsky |first1=Noah |last2=Grey |first2=Kathleen |title=Stromatolite branching in the Neoproterozoic of the Centralian Superbasin, Australia: an investigation into sedimentary and microbial control of stromatolite morphology |journal=Geobiology |date=16 August 2007 |volume=6 |issue=1 |pages=070816220552001–– |doi=10.1111/j.1472-4669.2007.00116.x|pmid=18380884 |s2cid=5495943 }} Stromatolites occur widely in the fossil record of the Precambrian but are rare today.{{cite journal |last1=Peters |first1=Shanan E. |last2=Husson |first2=Jon M. |last3=Wilcots |first3=Julia |title=The rise and fall of stromatolites in shallow marine environments |journal=Geology |date=June 2017 |volume=45 |issue=6 |pages=487–490 |doi=10.1130/G38931.1|bibcode=2017Geo....45..487P |url=http://strata.geology.wisc.edu/reprints/Peters_etal2017.pdf}} Very few Archean stromatolites contain fossilized microbes, but fossilized microbes are sometimes abundant in Proterozoic stromatolites.{{cite journal |last1=Lepot |first1=Kevin |title=Signatures of early microbial life from the Archean (4 to 2.5 Ga) eon |journal=Earth-Science Reviews |date=October 2020 |volume=209 |pages=103296 |doi=10.1016/j.earscirev.2020.103296|bibcode=2020ESRv..20903296L |s2cid=225413847 |doi-access=free |hdl=20.500.12210/62415 |hdl-access=free }}

While features of some ancient apparent stromatolites are suggestive of biological activity, others possess features that are more consistent with abiotic (non-biological) precipitation.{{Cite journal|last1=Grotzinger|first1=John P.|last2=Rothman|first2=Daniel H.|date=3 October 1996|title=An abiotic model for stromatolite morphogenesis|journal=Nature|volume=383|issue=6599|doi=10.1038/383423a0|pages=423–425|bibcode=1996Natur.383..423G|s2cid=4325802}} Finding reliable ways to distinguish between biologically formed and abiotic stromatolites is an active area of research in geology.{{cite journal |last1=Perri |first1=E. |last2=Tucker |first2=M. E. |last3=Mawson |first3=M. |title=Biotic and Abiotic Processes In the Formation and Diagenesis of Permian Dolomitic Stromatolites (Zechstein Group, NE England) |journal=Journal of Sedimentary Research |date=25 September 2013 |volume=83 |issue=10 |pages=896–914 |doi=10.2110/jsr.2013.65 |bibcode=2013JSedR..83..896P |url = https://www.researchgate.net/publication/260845254 |access-date=8 January 2022}} Multiple morphologies of stromatolites may exist in a single local or geological stratum, depending on specific conditions at the time of their formation, such as water depth.{{cite journal |last1=Meilijson |first1=Aaron |last2=Bialik |first2=Or M. |last3=Benjamini |first3=Chaim |title=Stromatolitic biotic systems in the mid-Triassic of Israel — A product of stress on an epicontinental margin |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=December 2015 |volume=440 |pages=696–711 |doi=10.1016/j.palaeo.2015.09.030|bibcode=2015PPP...440..696M }}

Most stromatolites are spongiostromate in texture, having no recognisable microstructure or cellular remains. A minority are porostromate, having recognisable microstructure; these are mostly unknown from the Precambrian but persist throughout the Palaeozoic and Mesozoic. Since the Eocene, porostromate stromatolites are known only from freshwater settings.{{Cite journal|last=Monty|first=C. L.|date=1981|editor-last=Monty|editor-first=Claude|title=Spongiostromate vs. Porostromate Stromatolites and Oncolites|url=https://link.springer.com/chapter/10.1007/978-3-642-67913-1_1|journal=Phanerozoic Stromatolites|language=en|location=Berlin, Heidelberg|publisher=Springer|pages=1–4|doi=10.1007/978-3-642-67913-1_1|isbn=978-3-642-67913-1|url-access=subscription}}

=Fossil record =

Some Archean rock formations show macroscopic similarity to modern microbial structures, leading to the inference that these structures represent evidence of ancient life, namely stromatolites. However, others regard these patterns as being the result of natural material deposition or some other abiogenic mechanism. Scientists have argued for a biological origin of stromatolites due to the presence of organic globule clusters within the thin layers of the stromatolites, of aragonite nanocrystals (both features of current stromatolites),{{Cite journal | doi = 10.1038/ngeo107 | volume = 1 | pages = 118–21 | last = Lepot | first = Kevin |author2=Karim Benzerara |author3=Gordon E. Brown |author4=Pascal Philippot

| title = Microbially influenced formation of 2.7 billion-year-old stromatolites | journal = Nature Geoscience | year = 2008 | issue=2 |bibcode = 2008NatGe...1..118L }} and of other microstructures in older stromatolites that parallel those in younger stromatolites that show strong indications of biological origin.{{Cite journal | last1 = Allwood | first1 = Abigail | last2 = Grotzinger |last3=Knoll |last4=Burch |last5=Anderson |last6=Coleman |last7=Kanik | title = Controls on development and diversity of Early Archean stromatolites | journal = Proceedings of the National Academy of Sciences | year = 2009 | doi = 10.1073/pnas.0903323106 | volume = 106 | pages = 9548–9555 | issue = 24 |bibcode = 2009PNAS..106.9548A | pmid=19515817 | pmc=2700989| doi-access = free }}{{cite book|title=Cradle of life: the discovery of earth's earliest fossils |url=https://archive.org/details/cradlelifediscov00scho_554 |url-access=registration |publisher=Princeton University Press |location=Princeton, N.J |year=1999 |pages=[https://archive.org/details/cradlelifediscov00scho_554/page/n97 87]–89 |isbn=978-0-691-08864-8 }}

File:Stromatolites hoyt mcr1.JPG (Cambrian) exposed at Lester Park, near Saratoga Springs, New York]]

File:Stromatolites.jpg fossilized stromatolites in the Siyeh Formation, Glacier National Park]]

File:CambrianStromatolites.jpg, Canada]]

Stromatolites are a major constituent of the fossil record of the first forms of life on Earth.{{cite journal |title=Patterns in Palaeontology: The first 3 billion years of evolution |first=Russell J. |last=Garwood |year=2012 |journal=Palaeontology Online |volume=2 |issue=11 |pages=1–14 |url=http://www.palaeontologyonline.com/articles/2012/patterns-in-palaeontology-the-first-3-billion-years-of-evolution/ |access-date=25 June 2015 |archive-url=https://web.archive.org/web/20150626104131/http://www.palaeontologyonline.com/articles/2012/patterns-in-palaeontology-the-first-3-billion-years-of-evolution/ |archive-date=26 June 2015 |url-status=live}} They peaked about 1.25 billion years ago (Ga) and subsequently declined in abundance and diversity,{{cite journal| year=1982 | title=Precambrian conical stromatolites from California and Sonora | author=McMenamin, M. A. S. | journal=Bulletin of the Southern California Paleontological Society | volume=14 | issue=9&10 | pages=103–105 }} so that by the start of the Cambrian they had fallen to 20% of their peak. The most widely supported explanation is that stromatolite builders fell victim to grazing creatures (the Cambrian substrate revolution); this theory implies that sufficiently complex organisms were common around 1 Ga.{{cite journal | author = McNamara, K.J. | title = Dating the Origin of Animals | journal = Science | volume = 274 | pages = 1993–1997 | date = 20 December 1996 | doi = 10.1126/science.274.5295.1993f | issue = 5295 | bibcode = 1996Sci...274.1993M | doi-access = free }}{{cite journal | author = Awramik, S.M. | title = Precambrian columnar stromatolite diversity: Reflection of metazoan appearance | journal = Science | volume = 174 | pages = 825–827 | date = 19 November 1971 | doi = 10.1126/science.174.4011.825 | pmid = 17759393 | issue = 4011 | bibcode = 1971Sci...174..825A| s2cid = 2302113 }}{{Cite encyclopedia | author=Bengtson, S. | year=2002 | chapter=Origins and early evolution of predation | encyclopedia=The Paleontological Society Papers | volume=8 | title=The fossil record of predation | editor=Kowalewski, M. | editor2=Kelley, P.H. | pages=289–317 | publisher=The Paleontological Society | chapter-url=http://www.nrm.se/download/18.4e32c81078a8d9249800021552/Bengtson2002predation.pdf | access-date=29 December 2014 }} Another hypothesis is that protozoa such as foraminifera were responsible for the decline, favoring formation of thrombolites over stromatolites through microscopic bioturbation.{{cite journal | last1=Bernhard | first1=J. M. | last2=Edgcomb | first2=V. P. | last3=Visscher | first3=P. T. | last4=McIntyre-Wressnig | first4=A. | last5=Summons | first5=R. E. | last6=Bouxsein | first6=M. L. | last7=Louis | first7=L. | last8=Jeglinski | first8=M. | title=Insights into foraminiferal influences on microfabrics of microbialites at Highborne Cay, Bahamas | journal=Proceedings of the National Academy of Sciences | volume=110 | issue=24 | date=28 May 2013 | doi=10.1073/pnas.1221721110 | pmid=23716649 | pmc=3683713 | pages=9830–9834| bibcode=2013PNAS..110.9830B | doi-access=free }}

Proterozoic stromatolite microfossils (preserved by permineralization in silica) include cyanobacteria and possibly some forms of the eukaryote chlorophytes (that is, green algae). One genus of stromatolite very common in the geologic record is Collenia.

The connection between grazer and stromatolite abundance is well documented in the younger Ordovician evolutionary radiation; stromatolite abundance also increased after the Late Ordovician mass extinction and Permian–Triassic extinction event decimated marine animals, falling back to earlier levels as marine animals recovered.{{cite journal | title=Microbialite resurgence after the Late Ordovician extinction | journal=Nature | volume=430 | pages=75–78 | year=2004 | doi=10.1038/nature02654 | author1=Sheehan, P.M. | author2=Harris, M.T. | pmid=15229600 | issue=6995 | bibcode=2004Natur.430...75S| s2cid=4423149 }} Fluctuations in metazoan population and diversity may not have been the only factor in the reduction in stromatolite abundance. Factors such as the chemistry of the environment may have been responsible for changes.{{cite journal | url=http://www.robertriding.com/pdf/riding2006mc.pdf | title=Microbial carbonate abundance compared with fluctuations in metazoan diversity over geological time | author=Riding, R. | journal=Sedimentary Geology | date=March 2006 | volume=185 | issue=3–4 | pages=229–38 | doi=10.1016/j.sedgeo.2005.12.015 | bibcode=2006SedG..185..229R | access-date=9 December 2011 | archive-url=https://web.archive.org/web/20120426041343/http://www.robertriding.com/pdf/riding2006mc.pdf | archive-date=26 April 2012 | url-status=live}}

While prokaryotic cyanobacteria reproduce asexually through cell division, they were instrumental in priming the environment for the evolutionary development of more complex eukaryotic organisms. They are thought to be largely responsible for increasing the amount of oxygen in the primeval Earth's atmosphere through their continuing photosynthesis (see Great Oxygenation Event). They use water, carbon dioxide, and sunlight to create their food. A layer of polysaccharides often forms over mats of cyanobacterial cells.{{cite journal |last1=Kawaguchi |first1=Tomohiro |last2=Decho |first2=Alan W. |title=Biochemical Characterization of Cyanobacterial Extracellular Polymers (EPS) from Modern Marine Stromatolites (Bahamas) |journal=Preparative Biochemistry and Biotechnology |date=January 2000 |volume=30 |issue=4 |pages=321–330 |doi=10.1080/10826060008544971|pmid=11065277 |s2cid=37979265 }} In modern microbial mats, debris from the surrounding habitat can become trapped within the polysaccharide layer, 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. Layered spherical growth structures termed oncolites are similar to stromatolites and are also known from the fossil record. Thrombolites are poorly laminated or non-laminated clotted structures formed by cyanobacteria, common in the fossil record and in modern sediments. There is evidence that thrombolites form in preference to stromatolites when foraminifera are part of the biological community.{{cite news |last1=Nuwer |first1=Rachel |author-link=Rachel Nuwer |title=What Happened to the Stromatolites, the Most Ancient Visible Lifeforms on Earth? |url=https://www.smithsonianmag.com/smart-news/what-happened-to-the-stromatolites-the-most-ancient-visible-lifeforms-on-earth-84714880/ |access-date=18 April 2020 |work=Smithsonian Magazine |agency=Smithsonian Institution |date=30 May 2013}}

The Zebra River Canyon area of the Kubis platform in the deeply dissected Zaris Mountains of southwestern Namibia provides a well-exposed example of the thrombolite-stromatolite-metazoan reefs that developed during the Proterozoic period, the stromatolites here being better developed in updip locations under conditions of higher current velocities and greater sediment influx.{{cite journal |author1=Adams, E. W. |author2=Grotzinger, J. P. |author3=Watters, W. A. |author4=Schröder, S. |author5=McCormick, D. S. |author6=Al-Siyabi, H. A. |year=2005 |title=Digital characterization of thrombolite-stromatolite reef distribution in a carbonate ramp system (terminal Proterozoic, Nama Group, Namibia) |journal=AAPG Bulletin |volume=89 |issue=10 |pages=1293–1318 |doi=10.1306/06160505005 |url=http://www.wellesley.edu/Astronomy/Wwatters/adams%20etal%20-%20digital%20models%20nama%20reefs%20-%20aapg%20bull%202005.pdf |access-date=9 December 2011 |archive-url=https://web.archive.org/web/20160307215400/http://wellesley.edu/Astronomy/wwatters/adams%20etal%20-%20digital%20models%20nama%20reefs%20-%20aapg%20bull%202005.pdf |archive-date=7 March 2016 |url-status=live}}

Modern occurrence

File:Lake Thetis-Stromatolites-LaRuth.jpg, Western Australia]]

File:20130118-HighbormeCay-Stromatolite-03.JPG, The Bahamas]]

=Formation=

Time lapse photography of modern microbial mat formation in a laboratory setting gives some revealing clues to the behavior of cyanobacteria in stromatolites. Biddanda et al. (2015) found that cyanobacteria exposed to localized beams of light moved towards the light, or expressed phototaxis, and increased their photosynthetic yield, which is necessary for survival.{{Cite journal|last1=Biddanda|first1=Bopaiah A.|last2=McMillan|first2=Adam C.|last3=Long|first3=Stephen A.|last4=Snider|first4=Michael J.|last5=Weinke|first5=Anthony D.|date=2015-01-01|title=Seeking sunlight: rapid phototactic motility of filamentous mat-forming cyanobacteria optimize photosynthesis and enhance carbon burial in Lake Huron's submerged sinkholes|journal= Frontiers in Microbiology|pages=930|doi=10.3389/fmicb.2015.00930|pmc=4561352|pmid=26441867|volume=6|doi-access=free}} In a novel experiment, the scientists projected a school logo onto a petri dish containing the organisms, which accreted beneath the lighted region, forming the logo in bacteria. The authors speculate that such motility allows the cyanobacteria to seek light sources to support the colony.

In both light and dark conditions, the cyanobacteria form clumps that then expand outwards, with individual members remaining connected to the colony via long tendrils. In harsh environments where mechanical forces may tear apart the microbial mats, these substructures may provide evolutionary benefit to the colony, affording it at least some measure of shelter and protection.

Lichen stromatolites are a proposed mechanism of formation of some kinds of layered rock structure that are formed above water, where rock meets air, by repeated colonization of the rock by endolithic lichens.Lichen Stromatolites: Criterion for Subaerial Exposure and a Mechanism for the Formation of Laminar Calcretes (Caliche), Colin F. Klappa, Journal of Sedimentary Petrology, Vol. 49 (1979) No. 2. (June), Pages 387–400, [http://archives.datapages.com/data/sepm/journals/v47-50/data/049/049002/0387.htm?doi=10.1306%2F212F7752-2B24-11D7-8648000102C1865D] {{Webarchive|url=https://web.archive.org/web/20141028133556/http://archives.datapages.com/data/sepm/journals/v47-50/data/049/049002/0387.htm?doi=10.1306%2F212F7752-2B24-11D7-8648000102C1865D|date=28 October 2014}}Paleobotany: The Biology and Evolution of Fossil Plants, Edith L. Taylor, Thomas N. Taylor, Michael Krings, page [http://archives.datapages.com/data/sepm/journals/v47-50/data/049/049002/0387.htm?doi=10.1306%2F212F7752-2B24-11D7-8648000102C1865D] {{Webarchive|url=https://web.archive.org/web/20141028133556/http://archives.datapages.com/data/sepm/journals/v47-50/data/049/049002/0387.htm?doi=10.1306%2F212F7752-2B24-11D7-8648000102C1865D|date=28 October 2014}}

= Saline locations =

Modern stromatolites are mostly found in hypersaline lakes and marine lagoons where high saline levels prevent animal grazing.{{Cite web |url=https://www.britannica.com/science/stromatolite |title=Stromatolite | geology}}{{Cite news |url=https://economictimes.indiatimes.com/news/science/oldest-evidence-of-life-on-earth-found-in-australia/articleshow/61658155.cms?from=mdr |title=Oldest evidence of life on Earth found in Australia |newspaper=The Economic Times}} One such location where excellent modern specimens can be observed is Hamelin Pool Marine Nature Reserve, Shark Bay in Western Australia. In 2010, a fifth type of chlorophyll, namely chlorophyll f, was discovered by Min Chen from stromatolites in Shark Bay.{{Cite journal | year=2010 | journal=Science | title=A Red-Shifted Chlorophyll | first6=H. . | volume=329 | issue=5997 | doi=10.1126/science.1191127 | pages=1318–1319 | pmid=20724585 | last6=Scheer | first5=B. A. | first2=M. . | last2=Schliep | first1=M. . | last3=Willows | first3=R. D. | last5=Neilan | first4=Z. -L. | last4=Cai | last1=Chen |bibcode=2010Sci...329.1318C | s2cid=206527174 }} Halococcus hamelinensis, a halophilic archaeon, occurs in living stromatolites in Shark Bay where it is exposed to extreme conditions of UV radiation, salinity and desiccation.Leuko S, Neilan BA, Burns BP, Walter MR, Rothschild LJ. Molecular assessment of UVC radiation-induced DNA damage repair in the stromatolitic halophilic archaeon, Halococcus hamelinensis. J Photochem Photobiol B. 2011 Feb 7;102(2):140-5. doi: 10.1016/j.jphotobiol.2010.10.002. Epub 2010 Oct 23. PMID: 21074452 H. hamelinesis possesses genes that encode enzymes employed in the repair of UV induced damages in DNA by the processes of nucleotide excision repair and photoreactivation.

Other locations include Pampa del Tamarugal National Reserve in Chile; Lagoa Salgada, Rio Grande do Norte, Brazil, where modern stromatolites can be observed as both bioherms (domal type) and beds; in the Puna de Atacama of the Andes; and near Sheybarah Island in Saudi Arabia.{{cite news |last=Strain |first=Daniel |date=6 December 2023 |title=Deep within an inhospitable desert, a window to first life on Earth |url=https://www.colorado.edu/today/2023/12/06/deep-within-inhospitable-desert-window-first-life-earth |url-status=live |archiveurl=https://archive.today/20231230225404/https://www.colorado.edu/today/2023/12/06/deep-within-inhospitable-desert-window-first-life-earth |archivedate=30 December 2023 |accessdate=30 December 2023 |work=University of Colorado}}{{Cite web |last=Banias |first=M. J. |date=2024-06-03 |title=New Study Says Life on Earth May Have Originated in Saudi Arabia 3.48 Billion Years Ago |url=https://thedebrief.org/new-study-says-life-on-earth-may-have-originated-in-saudi-arabia-3-48-billion-years-ago/ |access-date=2025-02-04 |website=The Debrief |language=en-US}}

Inland stromatolites can be found in saline waters in Cuatro Ciénegas Basin, a unique ecosystem in the Mexican desert. Alchichica Lake in Puebla, Mexico has two distinct morphologic generations of stromatolites: columnar-dome like structures, rich in aragonite, forming near the shore line, dated back to 1,100 years before present (ybp) and spongy-cauliflower like thrombolytic structures that dominate the lake from top to the bottom, mainly composed of hydromagnesite, huntite, calcite and dated back to 2,800 ybp.{{cite journal |author1=Kaźmierczak, J. |author2=Kempe, S. |author3=Kremer, B. |author4=López-Garcia, P. |author5=Moreira, D. |author6=Tavera, R. |name-list-style=amp |date=2011 |title=Hydrochemistry and microbialites of the alkaline caldera Lake Alchichica, Mexico |journal=Facies |volume=57 |page=543–570 |doi=10.1007/s10347-010-0255-8 |doi-access=free}} The only open marine environment where modern stromatolites are known to prosper is the Exuma Cays in the Bahamas.{{cite web |url=http://sepmstrata.org/Bahamas/pages/217-Stromatolites-Lee-Stocking-Exumas-Bahamas.html |title=217-Stromatolites-Lee-Stocking-Exumas-Bahamas Bahamas |access-date=2011-12-08 |archive-url=https://web.archive.org/web/20100326211512/http://sepmstrata.org/Bahamas/pages/217-Stromatolites-Lee-Stocking-Exumas-Bahamas.html |archive-date=26 March 2010 |url-status=dead}}{{cite journal |vauthors=Feldmann M, McKenzie JA |doi=10.2307/3515490 |title=Stromatolite-thrombolite associations in a modern environment, Lee Stocking Island, Bahamas |journal=PALAIOS |date=April 1998 |volume=13 |pages=201–212 |issue=2 |bibcode=1998Palai..13..201F |jstor=3515490}}

=Freshwater locations=

File:Pavilion Lake microbialite towers.jpg towers in Pavilion Lake, British Columbia]]

Laguna de Bacalar in Mexico's southern Yucatán Peninsula has an extensive formation of living giant microbialites (that is, stromatolites or thrombolites). The microbialite bed is over {{convert|10|km|mi|abbr=on}} long with a vertical rise of several meters in some areas. These may be the largest sized living freshwater microbialites, or any organism, on Earth.{{cite journal|author=Gischler, E.|author2=Gibson, M.|author3=Oschmann, W.|name-list-style=amp|title=Giant Holocene Freshwater Microbialites, Laguna Bacalar, Quintana Roo, Mexico|journal=Sedimentology|volume=55|pages=1293–1309|year=2008|doi=10.1111/j.1365-3091.2007.00946.x|issue=5|bibcode = 2008Sedim..55.1293G |s2cid=129828647 }}

A 1.5 km stretch of reef-forming stromatolites (primarily of the genus Scytonema) occurs in Chetumal Bay in Belize, just south of the mouth of the Rio Hondo and the Mexican border.{{cite journal|author=Rasmussen, K.A.|author2=Macintyre, I.G.|author3=Prufert, L|name-list-style=amp|title=Modern stromatolite reefs fringing a brackish coastline, Chetumal Bay, Belize|journal=Geology|volume=21|issue=3|pages=199–202|date=March 1993|doi=10.1130/0091-7613(1993)021<0199:MSRFAB>2.3.CO;2|bibcode = 1993Geo....21..199R |url=http://doc.rero.ch/record/14025/files/PAL_E1070.pdf }} Large microbialite towers up to 40 m high were discovered in the largest soda lake on Earth, Lake Van in eastern Turkey. They are composed of aragonite and grow by precipitation of calcite from sub-lacustrine karst-water.{{cite journal|author1=Kempe, S. |author2=Kaźmierczak, J.|author3=Landmann, G.|author4=Konuk, T.|author5=Reimer, A.|author6=Lipp, A.|name-list-style=amp |title=Largest known microbialites discovered in Lake Van, Turkey|journal=Nature|volume=349|date= 1991|issue=6310|page=605–608|doi=10.1038/349605a0|bibcode=1991Natur.349..605K|s2cid=4240438}} Freshwater stromatolites are found in Lake Salda in southern Turkey. The waters are rich in magnesium and the stromatolite structures are made of hydromagnesite.{{cite journal|author1=Braithwaite, C. |author2=Zedef V |name-list-style=amp |title=Living hydromagnesite stromatolites from Turkey|journal=Sedimentary Geology|volume=106|date=November 1996|page=309|doi=10.1016/S0037-0738(96)00073-5|issue=3–4|bibcode=1996SedG..106..309B}}

Two instances of freshwater stromatolites are found in Canada, at Pavilion Lake and Kelly Lake in British Columbia. Pavilion Lake has the largest known freshwater stromatolites, and NASA has conducted xenobiology research there,{{cite journal|title=Modern Freshwater Microbialites from Kelly Lake, British Columbia, Canada|vauthors=Ferris FG, Thompson JB, Beveridge TJ |journal=PALAIOS|volume=12|date=June 1997|jstor=3515423|issue=3|pages=213–219|doi=10.2307/3515423|bibcode=1997Palai..12..213F }} called the "Pavilion Lake Research Project." The goal of the project is to better understand what conditions would likely harbor life on other planets.{{cite journal|doi=10.1016/j.chemgeo.2010.03.016|author=Brady, A.|title=Photosynthetic isotope biosignatures in laminated micro-stromatolitic and non-laminated nodules associated with modern, freshwater microbialites in Pavilion Lake, B.C|journal=Chemical Geology|author2=Slater, G.F.|author3=Omelon, C.R.|author4=Southam, G.|author5=Druschel, G.|author6=Andersen, A.|author7=Hawes, I.|author8=Laval, B.|author9=Lim, D.S.S.|year=2010|volume=274|issue=1–2|pages=56–67|bibcode=2010ChGeo.274...56B}}

{{cite web

|url = https://nasa.gov/exploration/analogs/mapper.html

|title = NASA Help NASA Find Life on Mars With MAPPER

|publisher = NASA

|access-date = 2011-12-10

|archive-url = https://web.archive.org/web/20110930124647/http://nasa.gov/exploration/analogs/mapper.html

|archive-date = 30 September 2011

|url-status = live

}}

Microbialites have been discovered in an open pit pond at an abandoned asbestos mine near Clinton Creek, Yukon,

Canada.Power, I.M., Wilson, S.A., Dipple, G.M., and Southam, G. (2011) Modern carbonate microbialites from an asbestos open pit pond, Yukon, Canada, http://onlinelibrary.wiley.com/doi/10.1111/gbi.2011.9.issue-2/issuetoc {{Webarchive|url=https://web.archive.org/web/20120211140309/http://onlinelibrary.wiley.com/doi/10.1111/gbi.2011.9.issue-2/issuetoc |date=11 February 2012 }} Geobiology. 9: 180–195. These microbialites are extremely young and presumably began forming soon after the mine closed in 1978. The combination of a low sedimentation rate, high calcification rate, and low microbial growth rate appears to result in the formation of these microbialites. Microbialites at an historic mine site demonstrates that an anthropogenically constructed environment can foster microbial carbonate formation. This has implications for creating artificial environments for building modern microbialites including stromatolites.

File:'Crayback' stromatolite - Nettle Cave, Jenolan Caves, NSW, Australia.jpg, NSW, Australia]]

A very rare type of non-lake dwelling stromatolite lives in the Nettle Cave at Jenolan Caves, NSW, Australia.{{cite web |url=http://www.jenolancaves.org.au/compulsive_self-guided_cave_tour.php |title=Nettle Cave Self-guided tour |author=Jenolan Caves Reserve Trust |access-date=22 May 2011 |archive-url=https://web.archive.org/web/20110910062514/http://www.jenolancaves.org.au/compulsive_self-guided_cave_tour.php |archive-date=10 September 2011 |url-status=dead}} The cyanobacteria live on the surface of the limestone and are sustained by the calcium-rich dripping water, which allows them to grow toward the two open ends of the cave which provide light.{{cite journal|journal=Geomicrobiology Journal|volume =7|issue=4|year=1989|title=Cyanobacterially deposited speleothems: Subaerial stromatolites|doi=10.1080/01490458909377870|vauthors=Cox G, James JM, ((Leggett KEA)), ((Osborne RAL)) |pages=245–252}}

Stromatolites composed of calcite have been found in both the Blue Lake in the dormant volcano, Mount Gambier and at least eight cenote lakes including the Little Blue Lake in the Lower South-East of South Australia.{{cite journal|last=Thurgate|first=Mia E.|title=The Stromatolites of the Cenote Lakes of the Lower South East of South Australia|journal=Helictite, Journal of Australasian Cave Research|year=1996|volume=34|issue=1|page=17|url=http://helictite.caves.org.au/pdf4/34.01.Issue.Print.pdf|issn=0017-9973|access-date=14 March 2014|archive-url=https://web.archive.org/web/20140205061253/http://helictite.caves.org.au/pdf4/34.01.Issue.Print.pdf|archive-date=5 February 2014|url-status=live}}

References

External links

{{cite web |url=http://pilbara.mq.edu.au/wiki/Stromatolites |title=Stromatolites – Pilbara |access-date=2011-12-10 |archive-date=24 January 2012 |archive-url=https://web.archive.org/web/20120124213522/http://pilbara.mq.edu.au/wiki/Stromatolites |url-status=dead }}
{{cite web |url=http://www.scienceresearch.duq.edu/bio/biofac/jstolz/RIBS/ |title=Research Initiatives in Bahamian Stromatolites |access-date=2011-12-10}}
{{cite web |url=http://www.lagunabacalarinstitute.com/ |title=Laguna Bacalar Institute |access-date=2011-12-10 |archive-date=12 January 2012 |archive-url=https://web.archive.org/web/20120112062053/http://www.lagunabacalarinstitute.com/ |url-status=dead }}
[https://www.flickr.com/photos/jsjgeology/sets/72157632477572336 Stromatolite photo gallery], a teaching set from Ohio State University

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Category:Trace fossils

Category:Cyanobacteria

Category:Sedimentary rocks