Research using deep mantle krypton infers more about the ancestry of Earth’s outer solar system

Using Precise Measurements of Krypton Isotopes, UC Davis Researchers Prove Volatile Organic Compounds Were Incorporated into Earth Earlier Than They Thought

By MONICA MANMADKAR — [email protected]

According to a new study published in Nature by UC Davis researchers, krypton (Kr) isotopes provide insight into how, when and where carbon, nitrogen and water were brought to Earth. The study of these volatile organic compounds is an extremely important element in understanding the history of the Earth and, by extension, the history of other planets.

Gathering these isotopes from the Galápagos Islands, researchers Sandrine Péron and Sujoy Mukhopadhyay analyzed these isotopes for chemical fingerprints. According to the study, since krypton is composed of both meteoritic and atmospheric isotopes, this element can tell us a lot about Earth’s history and how its volatile elements like carbon, nitrogen and water initially developed.

“This study will [researchers] to better understand how the Earth came into existence and, more importantly, when these volatile elements developed in Earth’s history,” said Sandrine Péron, the study’s lead author and current Marie Skłodowska-Curie Fellow. Actions at ETH Zürich in Switzerland.

Péron conducted the research at UC Davis as a postdoctoral fellow working with Professor du Department of Earth and Planetary Sciences Sujoy Mukhopadhyay. She described how the deep mantle krypton remains unchanged since the formation of the moon, which is why isotopes can be used to infer when volatile compounds arrived on Earth. The volcanic patches of the Galápagos Islands draw magma from the mantle, which sits near the Earth’s iron core. By collecting the lava plumes themselves, researchers can use this magma to extract krypton isotopes. However, even with lava, researchers can only collect a few million atoms of the most abundant krypton isotopes.

“Since the process of inferring their impact is challenging, [Péron] was able to come up with a better method to measure mantle krypton with mass spectrometry,” Mukhopadhyay said. “[She] was able to concentrate krypton from rock samples where the samples would be free of air contamination and separated from argon and xenon.

Péron went on to explain how their study was the first to calculate all krypton isotopes exactly, including the rarest isotopes of krypton, Kr-78 and Kr-80. Using these isotopes as a fingerprint, the researchers hoped to find where the volatile elements and compounds originally came from in the asteroid belt, the inner solar system, or elsewhere.

“These isotopes essentially act like DNA in terms of lineage, [and are answering questions like] where did these elements come from and which bodies provided these essential elements for life,” Mukhopadhyay said.

The researchers soon discovered that the isotope fingerprints contained traces of early, carbon-rich meteorites that appeared very early in Earth’s history.

This reveals two new findings, Péron said. First, although isotopes show that volatile elements appeared very early in Earth’s history, not all isotopes have been accounted for in known meteorites. Second, the researchers found that the ratio of deep mantle krypton does not match atmospheric krypton isotope levels, meaning that some of those in the atmosphere were delivered when the moon formed. Otherwise, the ratio of krypton in the deep mantle to that in the atmosphere would be the same, Péron explained.

With this research in mind, Mukhopadhyay’s lab hopes to continue answering questions about why the fingerprint of krypton in Earth’s atmosphere is different from that of the deep mantle and how representative the measurements of the atmosphere are. study of the entire interior of the Earth’s mantle.

Written by: Monica Manmadkar — [email protected]

Arline J. Mercier