An international team of geologists has discovered, when studying volcanic rocks in Costa Rica that came from the hottest lava known in the last 2.5 billion years, according to the scientific journal Nature Geoscience. The research, led by Esteban Gazel, an associate professor at the Polytechnic Institute and State University of Virginia, brings new evidence on the thermal evolution of the Earth’s depths.
The team has analyzed the chemical composition of ancient lava rivers preserved in Costa Rica, which today form a geological complex with conditions of foundry and crystallization similar to the mysterious komatita of the Archaic eon. The komatita is a unique volcanic rock characteristic of that geological period that ended 2,500 million years ago and continues to be one of the most enigmatic in the evolution of planet Earth, according to Professor Gazel.
During the Archaic eon the Earth’s mantle temperature, located between the Earth’s core and crust, was warmer than it is today due to a large amount of radioactive heat produced by the decay of elements such as potassium or uranium.
“The komatita was a superheated version of lava rivers like the Hawaiians,” Gazel explains, adding that “it was so hot it had a white glow instead of red, and flowed on a planetary surface with very different atmospheric conditions, more Similar to Venus than the planet we live in today. ”
The team of researchers has studied the rocks of the 90-million-year geological complex in Costa Rica and found that they had concentrations of magnesium as high as the archaic komatite, as well as evidence of extremely high-temperature texture. According to geologists, the concentration of magnesium in basalts and komatites is related to the initial temperature of the magma as it melts, and the higher the concentration, the higher the magnesium content in the resulting rocks.
Presence of Olivino
Also, the presence of olivine, a green mineral that is the first to crystallize when a melted mantle cools, has served as an indicator of the temperature reached by the lava, since the higher, more aluminum incorporates its structure.
The study concludes that olivine from the rocks studied in Costa Rica crystallized at temperatures close to 1600 degrees Celsius, as high as those recorded by olivine in the komatita, marking a new record of lava in the last 2.5 billion years. For Gazel, the most “intriguing” of this study is that it suggests that the Earth could still be able to produce magma as hot as the komatite of the Archaic Aeon.
The researchers say that with the technology now available and these new data there are many opportunities to answer key questions about Earth’s geological and thermal evolution and to understand the geochemical messages that the Earth’s mantle sends to the surface of the planet.
