Typical biostructures of the dawn of terrestrial life found in Saudi Arabia

At the origin of earthly life, there is bacteriabacteria. Although it is difficult to find fossil traces of these first MicroorganismsMicroorganismsHowever, some left behind biosignatures, proving that life already existed on Earth approximately 3.5 billion years ago. These biosignatures are stromatolites.

Stromatolites are the origin of Earth's oxygenation

Stromatolites are biogenic structures, somewhat like coral reefs, made by colonies of cyanobacteria. Stromatolites appeared about 3.48 billion years ago, and then multiplied like hotcakes, to the point of affecting the chemical composition of the oceans and atmosphere! Because cyanobacteria produce oxygen. About 2.4 billion years ago, the activity of cyanobacteria was so great that they participated in the first stage of oxygenation of the terrestrial environment.

Hence, stromatolites dominated the shallow marine environment until the beginning of the Proterozoic Era (about 2 billion years ago), sometimes forming majestic coral reefs. Then the number of these biogenic structures declined, and if we still observe them today, it is generally only in specific, often harsh, environments, as in this hypersaline lake in the Atacama Desert or at Hot springsHot springs From Yellowstone. This does not mean that cyanobacteria have disappeared from our environment (they are still abundant), but rather that conditions are now more suitable for coral reef building. The best current analogues Construction worksConstruction works Of the stromatolites in open marine conditions are those found on the Exumas Islands in the Bahamas. Published study In the magazine geology However, reports indicate the recent and surprising discovery of a new field of modern stromatolites, on Shaybara Island, in Saudi Arabia.

An opportunity to understand stromatolite growth

The conditions of this carbonate platform are also relatively similar to those in the Bahamas: very shallow water depth, alternating between periods of emergence and subduction, a wide range of temperatures, oscillating between 8 and over 48°C, and very poor conditions. environment in NutrientsNutrients.

The Shibara field stromatolites have the peculiarity of being relatively small (only 15 cm wide), while fossil data reveal that these carbonate formations could have reached several meters in height and width in the past. Do current conditions limit the development of stromatolites, or do the Shaybara formations represent young forms? And I must say that we know very little about SpeedSpeed The growth of these vital structures.

The idea of ​​scientists now is to transfer some StromatoliteStromatolite From the Shibara to the aquarium to study its growth. An experiment that could provide a better understanding of how the first forms of life evolved on Earth and perhaps on other planets, such as Mars.