STROMATOLITES

STROMATOLITES strōma, mattress, bed, stratum lithos, rock Means “stony carpet”

Are considered as accretionary structure.

Formed in shallow water by trapping, binding and cementation.

Biofilm microorganisms (such as cyanobacteria) used as binding agent in cementation.

STROMATOLITES AND THROMBOLITES

Buildups of microbial mats that form in limestone- or dolostone-forming environments.

Together with oncoids (formerly called "algal biscuits" or "Girvanella"), they typically form by the baffling, trapping, and precipitation of particles by communities of microorganisms such as bacteria and algae.

ORIGIN

MORPHOLOGY Exist in the following forms:1. Conical2. Stratiform3. Branching4. Domal5. Columnar Occur mostly in the Precambrian and are rare

today. Few contains fossilized microbes. While some are results of biological activity. Most were considered to form by abiotic

precipitation.

FOSSIL RECORD Abundant during the Precambrian Period.

Archean fossil remains are presumed to be colonies of cyanobacteria.

Younger (that is, Proterozoic) fossils maybe premordial of the eukaryote chlorophytes.

Stromatolites are a major constituent of the fossil record for about the first 3.5 billion years of life on earth.

STRATIGRAPHY Become dimishingly uncommon in the

Archean.

Have higher production during the Proterozoic than the Phanerozoic eon.

The north, central U.S. and Wisconsin and Minnesota particularly have much old rock, and not surprisingly, considerable stromatolites and banded iron.

BANDED IRON FORMATION

Are massive, laterally extensive and globally distributed chemical sediment deposits.

That consist primarily of Fe-bearing minerals (iron oxides) and silica.

MODERN OCCURRENCE Are mostly found in hypersaline lake and

marine lagoons.

Are only known to prosper in open marine environment.

Also occurs in freshwater environment where the waters are rich in magnesium and those stromalites are made of hydromagnesite Mg5(CO3)4(OH)2.4H2O

Discovery of ancient stromatolites on Lake Superior's shore astounded the scientific world, reestablishing the age of the oldest known fossils. These stromatolites are visible as rings in an outcropping of Gunflint formation chert near Schreiber, Ontario.

Kona dolomite at Marquette, Michigan, clearly shows flat layers of small stromatolites about 1 cm tall.

Stromatolites, formed from layers of blue-green algae, are the world's oldest fossils. 

Pre-Cambrian stromatolites (commonly referred to as "Mary Ellen jasper") on display at the North American Museum of Ancient Life. The fossil was originally excavated in the Iron Range of Minnesota.

Stromatolites are considered the most intriguing fossils that are our window  into deep time on earth, the emergence of life, and the eventual evolving of the beautiful life forms from Cambrian to modern time.

In cross-section these stromatolites have a conspicuous curved layering

These compare well with excavated ancient stromatolites found around Marble Bar in

Western Australia dated at 3.45 billion years:

An example of this BIF rock in which the red is rich in hematite

The first eukaryotic life forms may be as old as 2 billion years ago. Grypania spiralis has been found in ancient

rocks in Michigan. This fossil is preserved because it formed formed

simple shells:

Gracefully coiled filaments are easily seen by the naked eye in these 2.1-billion-year-old fossils from the Upper Peninsula's Empire iron mine. They are possibly the oldest "megascopic" formations of life forms ever found. TSU-MING HAN, CLEVELAND

A microscopic cross section of columnar stromatolite at the Mary Ellen Mine, Biwabik, Minnesota.

REFERENCEShttp://

www.google.com.ph/images?hl=tl&q=images%20of%20stromatolites&um=1&ie=UTF-8&source=og&sa=N&tab=wi

http://www.google.com.ph/imgres?imgurl=http://www.fas.org/irp/imint/docs/rst/Sect20/stromatolites.jpg&imgrefurl=http://www.fas.org/irp/imint/docs/rst/Sect20/A12.html&h=285&w=308&sz=39&tbnid=PLETwQ4V10f3IM:&tbnh=108&tbnw=117&prev=/images%3Fq%3Dimages%2Bof%2Bstromatolites&hl=tl&usg=___OW25wgEHA04CtjpZpI4h5nqpJw=&sa=X&ei=3EphTIyrDs-qcYvmiekJ&ved=0CBYQ9QEwAA

http://www.google.com.ph/imgres?imgurl=http://ncse.com/files/images/Proterozoic_Stromatolites.jpg&imgrefurl=http://ncse.com/image/proterozoic-stromatolites&h=408&w=544&sz=80&tbnid=JKfF6d0Or-2SrM:&tbnh=100&tbnw=133&prev=/images%3Fq%3Dimages%2Bof%2Bstromatolites&hl=tl&usg=__sShXRjOf0PMo6CJxjIcAOaOtFnA=&

sa=X&ei=3EphTIyrDs-qcYvmiekJ&ved=0CBgQ9QEwAQ

http://www.google.com.ph/imgres?imgurl=http://imaginationconversion.files.wordpress.com/2008/03/stromatolites_lge.jpg&imgrefurl=http://rashidfaridi.wordpress.com/2009/12/18/stromatolite-the-oldest-fossils-encoding-the-mysteries-of-deep-time/&h=496&w=500&sz=66&tbnid=m7__SHQy-dboEM:&tbnh=129&tbnw=130&prev=/images%3Fq%3Dimages%2Bof%2Bstromatolites&hl=tl&usg=__QT7ezkL9QlwCFTzwIn_4D0paYyQ=&sa=X&ei=3EphTIyrDs-qcYvmiekJ&ved=0CBoQ9QEwAg

http://www.fossilmuseum.net/Tree_of_Life/Stromatolites.htmhttp://www.fossilmall.com/Science/About_Stromatolite.htm