It was a world of water without Earth or continents 3.2 billion years ago?

Earth is known to have gradually formed continents since its birth 4.6 billion years ago. There are many theories as to when the vast land was born. Meanwhile, according to the newly published research results, it is pointed out that 3.2 billion years ago the earth was still a world of water.

The University of Colorado and Iowa State University research team started the project around Pilbara Craton, a continental crust containing geological information in remote northwest Australia. It is said that the 3.2 billion-year-old oceanic plate of the Earth exists in this crust.

The team focused on the various types of oxygen contained in the crust and contained in oceanic plates 3.2 billion years ago. We analyzed the relative amounts of oxygen-16 (16O) and oxygen-18 (18O), the oxygen isotopes found in more than 100 rocks, and tried to compare the differences between the seas at that time and the present. Oxygen-18 is a little heavier than Oxygen-16 and is difficult to evaporate.

Analysis of oceanic plates 3.2 billion years ago revealed that seawater at that time contained more oxygen-18 than it is today. The most probable explanation for this is that no continents existed on Earth at the time. This is because when continents are formed, clay contained in the crust absorbs the heavy oxygen isotope, oxygen-18, in seawater.

Regarding the results of this analysis, the research team says that if there are no continents in the ocean, the oxygen isotope ratio is different from today, and that the value is exactly what the survey revealed. However, the findings do not indicate that there were no continents on Earth at the time. The research team is suspicious of the existence of small microcontinents all over the sea. However, I don’t think there were huge continents all over the place like now.

The team is also thinking about another reason for the existence of oxygen-18 in the ocean 3.2 billion years ago. If continents were formed much later than previously thought, clays that would absorb oxygen-18 could form in the sea rather than on land, which could lead to chemical characteristics similar to the findings.

One expert said that the oldest continental matter on Earth was 4 billion years old, and although continental emergence and growth have been constantly discussed so far, geologists are trying to estimate how continental volume has changed with time in various ways. . In this regard, he said this information is important because volcanic activity following continental growth and erosion has changed the composition of the Earth’s oceans and atmosphere, and that new research into when continents occurred would be welcome. The research team plans to investigate the proportion of oxygen isotopes in the ocean’s crust for younger age groups. Related information can be found here .