Earth – Chronicles the life
A new analysis of the world-famous fossils, whose age is estimated to 3,46 billion years finally helped to resolve the longstanding disputes of scientists. The study was conducted by experts from the University of Western Australia.
In 1993, American scientist bill SCHOPF (Bill Schopf) described a tiny sample (about 0.5-20 micrometers in diameter): these were carbon-rich silicon fiber breed age and 3.46 million years, found in the Pilbara region of Western Australia. He suggested that rocks were formed by some forms of bacteria, including cyanobacteria.
This sample, called the Apex chert microfossils, soon entered the textbooks and other popular scientific literature as the earliest evidence of life on Earth. However, its unusual color and complexity has caused scientists some questions.
The first doubts arose in 2002 when a team under the leadership of Martin Brasier (Martin Brasier) from Oxford University (which, incidentally, was a sponsor and the current study) found that breed was not part of the simple block of sedimentary rocks, but was extracted from hydrothermal rocks formed from the flow of underground fluids, for a long time exposed to high temperatures.
His team has put forward an alternative hypothesis that these curious structures were not mikrofossilii(the so-called species, which formed fossil organisms), and pseudofossils, which are formed as a result of the redistribution of carbon around the mineral granules in the process of hydrothermal events.
To settle disputes of scientists for a long time did not work: scientific equipment has only recently reached the resolution high enough to display the chemical composition and morphology of these microfossils.
At present researchers found out that the samples contain several rows of lamellar clay minerals, arranged in branched and tapered chain. The carbon on the edges of these minerals was absorbed during the circulation of hydrothermal fluids that created a deceptive impression of the cells that are rich in carbon.
Researchers David Weiss (David Wacey) and Martin Saunders (Martin Saunders) used transmission electron microscope to study ultra-thin sections, which helped to create nanoscale maps of size, shape, chemical minerals and the distribution of carbon.
Dr. Weiss said that such a distribution of carbon was not like he had seen before in authentic mikrofossilii. A false impression was made over a few plates of clay minerals, chemistry which is fully compatible with hydrothermal high temperature.
Thus, the researchers came to the conclusion that the sample still can be called pseudofossils. The discussion has led scientists to clarify the issues and methods necessary for search of life in space, including studies for signals from Mars and other celestial bodies.