A team of researchers succeeded, by deciphering the ages of tens and hundreds of millions of years old diamonds, to identify three different periods of their formation at a depth of about two hundred kilometers below present-day South Africa. Dr. Jacob Weiss: "This is a significant step not only in the study of diamonds, but also in the study of the evolution of the continents on Earth"
Diamonds are messengers from the depths of the earth. The process of their formation began at least 3.5 billion years ago, about three quarters of the time that the earth has existed, and continues today. Most of them crystallize at a depth of 150-200 kilometers, and reach the surface with the help of volcanic eruptions, the last of which occurred about 45 million years ago. Diamonds used in the gem industry are made of pure carbon, so they carry little information about their age and origin. Despite this, some of them contain tiny pockets of minerals and liquids - remnants of the environment in which the diamonds grew and the liquids from which they crystallized. These residues carry a lot of chemical information, so diamonds can be viewed as 'time capsules' - as messengers from ancient places and times that humans have no other way to reach, and scientists use them to gain insights into the Earth's crust.
A new study published in the prestigious journal Nature Communications found an accurate way to decipher the ages of fibrous diamonds, which contain fluids rich in water and carbon dioxide, and linked them to the geological history of South Africa, one of the oldest land areas on Earth. The team of researchers, led by Dr. Jacob Weiss from the Institute of Earth Sciences at the Hebrew University and Dr. Yael Kiro from the Weizmann Institute of Science, determined the ages of the diamonds by crushing the diamond, releasing the gases trapped in the liquid to measure the helium isotopes (helium atoms of different masses - 3He and 4He), and subsequent measurements of thorium and uranium in diamond. These made it possible to determine an age according to the rate of radioactive decay of uranium and thorium and the creation of 4He in this process. The data from the diamonds, combined with the geological evidence for the development of South Africa's mantle, made it possible to limit the maximum diffusion of helium in the diamond (the maximum rate at which the small, agile helium molecules can leak out of the diamond). According to Kiro, "this is the first time that the Earth is used as a kind of natural laboratory where we conduct an experiment lasting billions of years that allows us to estimate diffusion coefficients over time, a piece of information without which the conclusions about ages would be less significant." The research was done in collaboration with Prof. Steve Goldstein, Prof. Cornelia Klass and Prof. Gisela Winkler of Lamont-Doherty at Columbia University, and Prof. Jeff Harris from the University of Glasgow.
The study identified three different periods of diamond formation, each by a different liquid material, that occurred in the Earth's outer mantle in present-day South Africa. The oldest period occurred during the period of time between 2.6-700 million years ago, in which the composition of the fluids in the diamond was rich in carbonate minerals.
According to the researchers, there is a connection between the processes in which mountain ranges are formed and those that lead to the formation of carbonate liquids deep in the ground, but according to the researchers it is still unclear. Dr. Weiss from the Hebrew University explains: "We hypothesize that the period coincided with the formation of one of the largest mountain ranges on the surface of South Africa during the geological period of the Kiberian orogeny, as a result of a continental collision and similar to the formation of the Himalayan and Alps ranges today." The second period lasted 300-550 million years ago, a time when the Earth's continents, which were united, began to migrate and change their configuration. Indeed, the researchers found that the composition of the fluids was rich in silica minerals, which indicates a change in underground conditions at that time in the proto-African continent. The third period occurred 85-130 million years ago, in which the composition of the fluids changed again and was rich in salt compounds containing mainly sodium, potassium and chlorine. This composition indicates that the origin of the fluids that created these diamonds is not from the earth's mantle, but from the ocean floor that was pushed deep, under the land mass, following the movement of tectonic plates.
According to Weiss, "the research provides a better understanding of the terrestrial processes, which until now have been a mystery, and of the deep earth fluids that participate in these processes and create diamonds." He adds: "The method can be applied in other areas where diamonds are found in the world, including Australia, Brazil and northern Canada and Russia, with the aim of deciphering the deep geological history of those areas, and developing new insights into the development of continents on Earth."
Comments
We find and decipher shapes and connections at the still level.
How are we humans? What forms and connections may be found in the connection between us?
Why do we not discover new forms or new foundations in our relationships?
Food for thought:
https://www.youtube.com/watch?v=w3kWsVKc_CM&t=8s
It is difficult to know anything about such a distant period by carbon 14 so that everything is extremely weak hypotheses.