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Scandinavia was ‘born’ from Greenland 3.75 billion years ago, study finds

A recent study conducted by the Department of Geosciences and Natural Resource Management at the University of Copenhagen discovered that Scandinavia probably originated from Greenland.

In a statement released, the scientists noted that the “foundation” upon which Denmark and Scandinavia rest was probably ‘born’ from Greenland approximately 3.75 billion years ago.

They employed isotopic compositions comprising lead, hafnium, and oxygen to trace the chemical evidence, starting from the Fennoscandian Shield to Greenland. This paved the way for researchers to determine the age and origin of Scandinavian bedrock.

The oldest Earth’s crust originates in Greenland

“Our data suggest that the oldest part of Earth’s crust beneath Scandinavia originates in Greenland and is about 250 million years older than we previously thought,” said Professor Tod Waight, a geologist at the Department of Geosciences and Natural Resource Management.

Scientists stumbled upon the oldest part of the Earth’s crust beneath Scandinavia, sediments of which they traced back to Greenland. 

This finding revealed that the Scandinavian bedrock is roughly 250 million years older than previously thought. The rocks were recovered from the regions–Pudasjarvi and Suomujarvi in Finland. According to the statement, the zircon chemical fingerprints matched those of some of the oldest rocks on the planet found in West Greenland’s North Atlantic Craton.

“The zircon crystals we found in river sand and rocks from Finland have signatures that point towards them being much older than anything ever found in Scandinavia while matching the age of Greenlandic rock samples,” explained Andreas Petersson, Department of Geosciences and Natural Resource Management researcher.

“At the same time, the results of three independent isotope analyses confirm that Scandinavia’s bedrock was most likely linked to Greenland,” Petersson added.

Geological material eventually formed Scandinavia

The study is helping scientists better understand the development of life on Earth by shedding light on continental evolution and could potentially propel scientists to reevaluate our understanding of early Earth’s development.

“Understanding how continents formed helps us understand why ours is the only planet in the solar system with life on it,” Petersson said. 

“Without fixed continents and water in between them, we wouldn’t be here. Indeed, continents influence both ocean currents and climate, which are crucial for life on Earth,” he continued.

The statement noted that Denmark, Sweden, Norway, and Finland— placed on top of the Earth’s crust referred to as the Fennoscandian Shield or the Baltic Shield— broke away from Greenland as a “seed” and shifted for hundreds of millions of years until it “took root” where Finland is today.

During this event, the plate expanded while fresh geological material collected around it eventually developed into Scandinavia. When the crust separated from Greenland, the Earth’s appearance changed to what it is currently.

“Earth was probably a watery planet, like in the movie Waterworld, but without any oxygen in the atmosphere and without emergent crust. But, because that’s so far back in time, we can’t be really be sure about what it actually looked like,” Waight remarked. 

Petersson further explained: “This is unique in our solar system. And, evidence of liquid water and a granite crust are key factors when trying to identify habitable exoplanets and the possibility of life beyond Earth.”

The study was published in the scientific journal Geology.

Study Abstract

Enabling the build-up of continental crust is a vital step in the stabilization of cratonic lithosphere. However, these initial crustal nuclei are commonly either destroyed by recycling or buried by younger rocks. In the Fennoscandian Shield, the oldest rocks are ca. 3.5 Ga, but ca. 3.7 Ga inherited and detrital zircons suggest the presence of an older, unexposed crustal substrate. We present U-Pb, O, and Hf isotope data from detrital zircons of three major Finnish rivers as well as zircon O and Hf isotope data from previously dated rocks of the Archean Suomujarvi and Pudasjarvi complexes, central Finland. Combined, these data indicate a previously unidentified ca. 3.75 Ga crustal nucleus in the Fennoscandian Shield. This adds to the growing number of Eoarchean nuclei recognized in Archean terranes around the globe, highlighting the importance of such nuclei in enabling the growth of continental crust. The isotope signatures of the Fennoscandian nucleus correlate with equivalent-aged rocks in Greenland, consistent with a common Eoarchean evolution for Fennoscandia and the North Atlantic craton.

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 4/2/2024

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