2023-07-28 04:00:13
Earth dynamics is a subject that has long challenged scientists. The tectonic plates, these vast pieces of the earth’s crust, are constantly in motion, creating mountains, separating the seabed and triggering devastating earthquakes. A recent study reveals that these movements began regarding 3.2 billion years ago. A revelation that sheds new light on the transformation of our planet (A planet is a celestial body orbiting around the Sun or another star of …), a mass (The term mass is used to designate two quantities attached to a…) rock relatively homogeneous with the Earth (Earth is the third planet of the Solar System by order of distance…) as we currently know it.
The imprints of the tectonics of the Earth’s plates have been found in deposits dating back 3.2 billion years.
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According to the study co-directed by Zheng Xiang Li, geodynamicist at the University of Curtin in Australia (Australia (officially the Commonwealth of Australia) is a country of…), 3.2 billion years mark a turning point in the history of our planet. Li and his team discovered a change in the chemical composition of rocks formed in the mantle at that time, a sign of a “remixing” process. This process resulted in transport (Transportation is the act of carrying something, or someone, from one place to another, most…) of minerals from the crust to the mantle and from the rocks of the mantle to the surface (A surface generally designates the superficial layer of an object. The term a…), an undeniable imprint of tectonics (Tectonics (from the Greek “Ο?ΞΊΟΟΞ½” or “tekt?n”…) plates.
As part of their new study, Li, geochemist Luc Doucet and their colleagues analyzed significant lead-zinc deposits in Australia. They used the ratios of molecular variations of uranium, thorium (Thorium is a chemical element, a metal of the family of actinides, symbol…) and lead (Lead is a chemical element of the family of crystallogens, symbol Pb and…) as a clock to measure events that occurred far in the past (The past is first of all a concept linked to time: it is made up of all…) of the Earth.
According to Denis Fougerouse, co-author of the study, Australian deposits range from 3.4 billion years to 285 million years. The analysis confirmed that 3.2 billion years ago was a tipping point. Prior to this, the Earth had differentiated into a “tiered cake” pattern of core, mantle and crust. Stratification due to gravity (Gravitation is one of the four fundamental interactions of physics.), the heavier elements sinking towards the core and the lighter elements rising towards the crust. However, 3.2 billion years ago, these layers began to remix, with plate tectonics pushing scraps of crust into the mantle, and volcanism bringing mantle elements to the surface.
The study, published in the August issue of the journal Earth-Science Reviews, shows that the beginning of this process was complex and did not necessarily happen simultaneously across the entire planet. Researchers are now working on computer simulations to understand how plate tectonics probably began 3.2 billion years ago.
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