Part of the first crust, which contains the oldest rocks at all, is lying on the beaches of Hudson Bay in northeastern Canada, specifically in a formation known as the “Novawgitock Greenstone” belt.
Scientists have agreed for years that the age of these rocks is at least 3.8 billion years, but a new study published in a magazine Science It indicates that her age may reach 4.16 billion years, which makes it older than any other known rocks of about 160 million years, and perhaps the only witness remaining of the “hellish age” within the history of the earth, or known as Hadian.
Between doubts and assurances: a journey of rocks history
In general 2008، Jonathan O’Neill, geologist and assistant professor at the Canadian University of Ottawa, and his colleagues announced that the rocks of the Novawgitock Greenstone belt may date back to 4.3 billion years, but that O’Neil indicated in a statement to Al -Jazeera Net that these results were met with great reservations from other scientists.
O’Neil explained that this is due to the dependence of the study on radioactive history using Samarium and Newmium analogues, instead of zircon metal, which is the golden standard for rock history due to its stability over time.
The difficulty of relying on samarium is that it decomposes to nodimum through two different tracks, namely the Samarium-146 road to the noodimium-142, a relatively short-short age of approximately 96 million years, and the Samarium-147 route to the noodimium-143, with a long half-age that extends to trillion years.
The half -age is defined as the time required to decompose half the amount of radioactive material or to lose the radioactive element half of its radiological activity. In other words, if you have 100 grams of a radioactive element, the age of half is the time after that only 50 grams remain, after other atoms have decomposed into different elements.
“We suggested in 2008 that the age of volcanic rocks is 4.3 billion years, relying on Samarium-146 decomposition to the noodimium-142, but relying on Samarium-147 decomposition to the Newmium-143 is given a younger age ranged between 3.3 and 3.8 billion years, which is the main reason behind the controversy around its age.”
A new methodology that flips the scales
O’Neil explains to Al -Jazeera Net that the contrast at the life of the rocks depending on the two different tracks of radioactive history is caused by deformation in the radiological record, as the decomposition of the counterpart of half -life is still active to this day, and it can be sensitive to every thermal event that the rocks witnessed throughout its history.
He adds: “During the decomposition, the long -life path can reset itself partly or completely to give the ages of the apparent, while it is very difficult to influence the short -live track because the decomposition has already ended after 4 billion years has passed.”
To exceed this problem, the team resorted to rocks that were later formed after penetrating the lashing layer of the old Earth crust, and since these fiery formations are newer than the original rocks, their history determines the minimum life of the Novawgitok Greenstone belt.
It is noteworthy that the history of these rocks using both radioactive tracks gave identical results: 4.16 billion years, which strongly enhances the hypothesis that the rocks of the Novawgitock Greenstone belt are due to the hellish age, which is the oldest ever to this day.
O’Neil expects to find opposition in the scientific milieu this time also by claiming that this old age is the result of mixing with the rocks of the first shell that no longer exists, but it confirms that to obtain the same result using both radiation tracks, the mixing must have occurred in full accuracy: in time, in the appropriate quantities, and with a very accurate proportion of analogues.
In this regard, O’Neill says: “It also requires a mixture of mixing that only affects specific rocks in the Novawgitok Greenston belt, this is not an impossible scenario but I consider it very excluded and the simple alternative is that the rocks are very old!”
The importance of this discovery
It is believed that the earth began to divide into tectonic sheets about 3.8 billion years ago, which led to the burial of the old shell under the surface and its exposure to thermal and chemical transformation, but parts of the ancient crust survived this fate in the areas far from the edges of the sheets, and the Novawgitok Greenstone belt is one of the most prominent of these areas, as it remained relatively isolated from the major distortions retained a unique geological record of Its type.
O’Neill sees that, besides the time value of this belt, it may carry decisive evidence to understand the beginnings of our planet, as it dates back to the first 500 million years of the life of the earth, as it helps us to understand how the Earth’s crust and the first continents formed and what geodminic processes that contributed to this and the surrounding environmental conditions.
Besides, some of the rocks of this belt were formed from the deposit of sea water materials, and may help rebuild the chemistry of the first oceans, its temperature, and perhaps the atmosphere in that era, and even reveal the oldest traces of life on our planet.
It is worth noting that, despite the importance of this discovery, the future of research in this region faces many difficulties. The site has been closed to more fossils after the collection of samples over the past years has damaged the region.