This is precisely what transpired in the ancient history of Earth, a groundbreaking study led by geophysicist Zheng Xiang Li from Curtin University (Australia) has demonstrated.
In 2020, Dr. Li’s team reported changes in the chemical composition of rocks formed in Earth’s crust around 3.2 billion years ago, hinting at the occurrence of a large-scale planetary mixing event. In a recent publication on Science Direct, they reveal evidence of this phenomenon through “treasures” unearthed from lead-zinc mines in Australia.
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Earth 3.2 Billion Years Ago – Graphic Illustration from LIVE SCIENCE
The U-Th-Pb system, encompassing the isotopes of uranium, thorium, and lead, is among the most recognized “geological clocks.”
Australian mines have helped them ascertain that our planet had a “cosmic shake-up” during that era, resulting in isotope ratios divergent from the primitive Solar System materials found in occasional primitive carbonaceous chondrites.
All of these findings recount a pivotal milestone for Earth: transitioning from a solid, placid sphere akin to Venus or Mars, it commenced vigorous tectonic activity around 3.2 billion years ago, when the planet was a mere 1.3 billion years old.
Entering the “crunch point,” this primitive tectonic activity dramatically mixed materials both on and within Earth. Today, Earth still engages in tectonic activity. The planetary crust is effectively composed of nearly 20 tectonic plates, in constant motion and carrying oceans or continents on their backs. This is the reason why throughout planetary history, continents have repeatedly amalgamated into supercontinents and then fragmented as observed today.
This process of tectonic plate activity is immensely significant for us, as it fuels the chemical reactions necessary for the formation of primitive life, while also aiding in maintaining a planet with an atmosphere, hydrosphere, and stable environment that can support and sustain evolving life.
The crucial milestone uncovered by Australian scientists – 3.2 billion years – also aligns with certain evidence of the presence of primitive life at that time.
Hence, it can be asserted that scientists have unearthed an immensely vital “lost chapter” of the planet’s history.