Research team finds that some magmas originate from mantle portions containing remnants of Earth's earliest crust

In an international collaboration, Earth scientists at the University of Cologne and Freie Universitt Berlin have discovered that some magmas on Earth originate from mantle portions. The ancient material must have been buried in a grave more than 4 billion years ago and has been there ever since.

The plate tectonic regime of our planet recycles crustal material via large-scale mantle convection at much smaller time scales. It has been assumed that the remnants of early geological processes on Earth can only be found on other planets. According to the study, long-term preservation of Hadean protocrust in Earth's mantle, magmatic rocks that erupted throughout Earth, has recently appeared in the Proceedings of the National Academy of Sciences.

Up to 3.55 billion-year-old rocks from southern Africa were investigated by the geologists. There were anomalies in the composition of the element W. The relative abundance of 182W is related to geological processes that must have taken place after 4.5 billion years ago.

The model calculations show that the observed 182W isotope patterns can be explained by the recycling of Earth's earliest crust into mantle material that ascends via the lower mantle to generate lavas. The study shows that the earliest part of Earth is still buried in the lowermost mantle, as shown by the different types of modern volcanic rocks.

We assume that the lower layers of the crust became heavier than their surroundings due to a geological maturation process and therefore sank into the Earth's underlying mantle. The University of Cologne's Institute of Geology and Mineralogy has a similar lava lamp.

This insight gives us a chance to understand how large continents formed over the history of our planet. It explains how our current, oxygen-rich atmosphere evolved, setting the stage for the origin of complex life.

The early Earth's fingerprints can be compared with those of other planets obtained during space missions. Mars has a very old surface due to the lack of plate tectonics, and its composition may correspond to that of the young Earth, according to data from Mars missions and studies of Martian meteorites.

More information: Jonas Tusch et al, Long-term preservation of Hadean protocrust in Earth's mantle, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2120241119 Journal information: Proceedings of the National Academy of Sciences Citation: Research team finds that some magmas originate from mantle portions containing remnants of Earth's earliest crust (2022, April 28) retrieved 29 April 2022 from https://phys.org/news/2022-04-team-magmas-mantle-portions-remnants.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.