Zircon crystals, like a time capsule, can store traces of hundreds of millions of years of life in the form of biogenic carbon. Using new techniques, scientists from the University of Heidelberg were able to trace very old and rare examples of the mineral zircon containing graphite inclusions where light carbon could be identified as a remnant of early life.
According to the researchers, this opens up new opportunities to study the early stages of our planet’s existence; Neither the fossils nor the deposits were preserved in their original form.
Zircon mineral grains are formed from magma, that is, molten rock, in an extremely hot and internally hostile environment. However, the heated organism residues were transformed into carbon dioxide and methane and precipitated as graphite in the zircon mineral at a temperature of about 700°C.
Study author Dr., of the Heidelberg University Earth Sciences Institute. “The particular isotopic signature of biogenic carbon is highly conserved in most inclusions, leaving a distinctive imprint of early life forms,” explains Manfred Vogt.
Researchers emphasize that it is extremely difficult to measure. First, all traces of graphite in zircon crystals, some of which are only a few micrometers in size and therefore a hundred times smaller than a human hair, must be found and identified. To exclude carbon contamination from the environment, non-destructive Raman scattering microspectroscopy is used to examine encapsulated inclusions in zircons. Next, the zircons are bombarded with an ion beam to reveal graphite inclusions so that their carbon isotopic composition can be analyzed.
A study participant, Dr. “In this process, we can remove carbon layers that are only a few nanometers thick and measure them separately, so we can get many data points for a single inclusion to reveal possible variations,” explains Winfried Schwartz. The results of the research have been published Geochimica and Cosmochimica Acta.
Zircons are among the oldest minerals on Earth, some of them more than four billion years old. “They can teach us more than 96% of Earth’s history. During the first hundred million years, these crystals represent the only known information about very early conditions on the planet. already revealed that it exists,” explains Dr. Vogt.
Source: Port Altele
