Life on Earth appeared in the Archean period, more than 3.6 billion years ago, in oceans whose composition was very different from what we know today. A new study also reveals the extent to which geological processes may have affected the concentrations of certain metals, nutrients essential for metabolic reactions.
You will also be interested in this
(on video) Is the key to life on Earth hidden in solar storms? In adolescence, our Sun was agitated by innumerable and terrible explosions. Without the usual solution…
If we know that life appeared in the oceans, few constraints currently exist on the chemical composition of these primitive oceans, and especially on the presence of. NutrientsNutrients Being able to promote the emergence of the first living organisms.
if today zinczinc And this coppercopper One of the essential nutrients for all terrestrial life, especially for building proteinproteinStudies show that the earliest life forms may have given priority to others metalsmetals, turnturnThe molybdenummolybdenum And this manganesemanganese In fact the first metabolic organisms were apparently preferentially selected for making proteins. A deviation from the present situation may indicate that these metals were present in significant concentrations in the Archean oceans 3.6 billion years ago. But how can we explain this difference in the composition of the oceans compared to today? Two researchers may have found the answer: the presence of a certain mineral, greenlight.
A primitive miniature ocean in the laboratory
To understand, we must remember that at this time, photosynthetic organisms had not yet appeared and the atmosphere, like the oceans, was very low in oxygen. Analysis of rare sedimentary rocks related toarchaeaarchaea This also shows that the world’s water was rich in iron. silicasilica, But for the rest, and especially regarding the concentrations of various nutrients, the question remains open.
To find out the exact composition of Archean seawater, scientists decided to recreate a miniature ocean in the laboratory based on data provided by Archean sedimentary rocks to constrain the environmental conditions of the marine environment.
Appearance of a new mineral and effect on metal concentrations
Researchers immediately observed the formation of a new mineral: it was silicatesilicate Iron, called greenlight. An observation supported by analysis of Archaean rocks indicating that greenlite was certainly an important mineral. teretere primitive, maybe even one of mineralmineral The most important of the Archaean.
But while greenlight is created by the reaction of silica and iron in water, scientists have noticed another phenomenon: drastic changes in the concentrations of certain metals. zinc, copper and vanadiumvanadium are actually absorbed by greenlight. Thus the sea water becomes depleted of these nutrients, and becomes relatively rich in manganese, molybdenum and CadmiumCadmium, not affected by the formation of new minerals. These results have been published in the journal nature geologyThis therefore agrees with biologists’ predictions on the priority of metabolic systems to be the first to utilize these nutrients available in large quantities.
Experience also shows that greenlight can form in deep environments at the level of both source hydrothermalsource hydrothermal, just like shallow water. The permanent storage of zinc, copper and vanadium from this mineral formation may also have had a lasting impact on the structure of the oceans.