STROMATOLITES
STROMATOLITES
strōma, mattress, bed, stratum
 lithos, rock
 Means “stony carpet”

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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. Conical
2. Stratiform
3. Branching
4. Domal
5. 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
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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
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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 2.1billion-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.
REFERENCES
http://www.google.com.ph/images?hl=tl&q=images
%20of%20stromatolites&um=1&ie=UTF8&source=og&sa=N&tab=wi
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/images/Proterozoic_Stromatolites.jpg&imgrefurl=http://ncs
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onversion.files.wordpress.com/2008/03/stromatolites_lge.jpg
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tromatolite-the-oldest-fossils-encoding-the-mysteries-ofdeep-time/&h=496&w=500&sz=66&tbnid=m7__SHQydboEM:&tbnh=129&tbnw=130&prev=/images%3Fq%3Dim
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http://www.fossilmuseum.net/Tree_of_Life/Stromatolites.htm
http://www.fossilmall.com/Science/About_Stromatolite.htm