Ancient Magma From Earth's Early Days Discovered in Rocks From Greenland

Our planet's surface has seen a thing or two in its 4.5 billion-odd-years of existence. Weathered by ocean, corroded by wind, and remolded by the relentless turnover of plate tectonics, we might assume nothing remains of Earth in its most primitive state.

Yet an analysis of rocks from a formation in Greenland reveals traces of a geological journey that took place at a time when our rocky world was little more than a molten ocean of magma, and it could fill in missing details on our ancient past.

Researchers from the University of Cambridge in the UK and Carleton University in Canada paid particular attention to signature levels of iron isotopes in a powdered sample of basalt taken from the northern parts of the Isua Greenland Belt (ISB).

Along with a study of its tungsten, the chemical signatures reflect the basalt's birth from a mix of components from different parts of the mantle at a time when Earth's entirely molten surface was hardening.

The Isua belt is a strip of crust in Greenland's southwest that has remained relatively unchanged for a mind-blowing 3.7 billion years, officially making them the oldest rocks on Earth.

For more than half a century the ISB has been a regular haunt for planetary scientists and biologists keen to learn more about how our planet's crust formed, and how its chemistry – including the earliest forms of life – might have emerged. Read the free article.