Microbial
Induced Sedimentary Structures
Geological
Time: Paleoarchean (3.48 Billion Years Old)
Size: Fossil
is 115 mm by 55 mm by 7 mm (maximum)
Fossil Site:
North Pole Dome, Dresser Formation, Pilbara, Western Australia
Code: AS16026
Price: Sold
Description:
I was fortunately able to acquire a few examples of the currently
oldest-known fossils from the early time of life on earth: microbial
mats from the Dresser Formation of Western Australia. These specimens
are some 50 MILLION YEARS Older than the Strelly
Pool Stromatolites (see my other listings) also found in Western Australia. These
structures were the response of microbial mats to sedimentary
dynamics through processes that do not involve a production of
minerals within the organic matrix as do stromatolites. Formation
of such mats arise from primary shaping by physical sediment
dynamics (e.g erosion, deposition, latency) followed by mineralization
of the organic material. For example erosional stress by water
currents passing over the mat triggers biostabilization in order
to prevent burial. When a mat is exposed to sediment deposition,
the matt’s filaments orient themselves perpendicularly
to the surface, reaching into the water above causing turbulence
known as baffling. This induces the fallout of sediment which
are then incorporated into the mat’s structure. While the
mats themselves are formed by these primary processes, the secondary
process of rapid in situ mineralization is what preserves them.
Comparison of the structures seen within the deposits of the
Dresser Formation with those of later and even extant microbial
mats have led the authors of the paper referenced below that
they are indeed biogenic in nature. Perhaps when Man has made
it to the surface of Mars similar type structures will be found.
Reference: Astrobiology, Vol 13 No 12, 2013, pp 1103-1124 |
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