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A team of Australian researchers appear to have found fossilized evidence of life existing in some of the world's oldest sedimentary rocks, in the Isua supracrustal belt (ISB) in southwestern Greenland along the edge of that island's icecap -- an area so remote that the team had to travel there by helicopter. The ISB is an Archean greenstone (igneous rock containing feldspar and hornblende noted for its color) belt, which consists of metamorphosed mafic volcanic and sedimentary rocks, is somewhere between 3.7 and 3.8 Billion years old (byo).
The team, led by Professor Allen Nutman, a geologist at University of Wollongong's School of Earth & Environmental Sciences, were examining a newly exposed, formerly snow-covered outcropping of iron- and magnesium-rich dolomite sedimentary rocks, and noticed some wavy and conical structures ranging from 1 to 4 cm (0.39-1,57") tall that appear to be the fossilized remnants of stromatolite microbial colonies.
Stromtolites are microbial mats of microorganisms, especially cyanobacteria, which are still being formed today by bacterial communities living in shallow water. The ISB sedimentary layers containing these stromatolites overlay volcanic rocks that have been dated at being 3.709 billion years old, and are directly under dolomite sediments and banded iron formations with thorium-uranium zircons dated at 3.695 ± 0.4 byo, so these stromatolites formed approximately 3.7 billion years ago.
If confirmed this Greenland discovery predate the oldest previously known stromatolite remains, found in the Dresser Formation of the Pilbara Craton in western Australia, by 220 million years and provide further evidence that life on earth emerged rapidly after the earth formed.
Further Reading:
Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures Full article behind a pay wall
Life thrived on young Earth: scientists discover 3.7-billion-year-old fossils
Scientists find 3.7 billion-year-old fossil, oldest yet
3.7-billion-year-old fossils may be the oldest signs of life on Earth
The team, led by Professor Allen Nutman, a geologist at University of Wollongong's School of Earth & Environmental Sciences, were examining a newly exposed, formerly snow-covered outcropping of iron- and magnesium-rich dolomite sedimentary rocks, and noticed some wavy and conical structures ranging from 1 to 4 cm (0.39-1,57") tall that appear to be the fossilized remnants of stromatolite microbial colonies.
Stromtolites are microbial mats of microorganisms, especially cyanobacteria, which are still being formed today by bacterial communities living in shallow water. The ISB sedimentary layers containing these stromatolites overlay volcanic rocks that have been dated at being 3.709 billion years old, and are directly under dolomite sediments and banded iron formations with thorium-uranium zircons dated at 3.695 ± 0.4 byo, so these stromatolites formed approximately 3.7 billion years ago.
If confirmed this Greenland discovery predate the oldest previously known stromatolite remains, found in the Dresser Formation of the Pilbara Craton in western Australia, by 220 million years and provide further evidence that life on earth emerged rapidly after the earth formed.
Further Reading:
Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures Full article behind a pay wall
Life thrived on young Earth: scientists discover 3.7-billion-year-old fossils
Scientists find 3.7 billion-year-old fossil, oldest yet
3.7-billion-year-old fossils may be the oldest signs of life on Earth
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