A novel investigation, spearheaded by Dr. David Hernández Uribe of the University of Illinois Chicago, has employed sophisticated computational simulations to scrutinize the genesis of magmas believed to hold profound insights into the genesis of Earth’s continental masses.
Hadean Earth. Image credit: Alec Brenner.
Magma represents the incandescent subterranean fluid that, upon thermal dissipation, solidifies into rock and mineral formations.
Dr. Hernández Uribe sought magmatic compositions exhibiting the distinct chemical fingerprint of rare zircon deposits, originating from the Archaean eon (spanning 2.5 to 4 billion years ago), a period historically considered the dawn of continental formation.
In a recent scholarly contribution, researchers posited that Archaean zircons could exclusively arise from subduction processes—a geological phenomenon where adjacent tectonic plates converge underwater, resulting in the uplift of terrestrial material.
This very mechanism remains active today, precipitating seismic events, volcanic expulsions, and the continuous reconfiguration of continental coastlines.
However, Dr. Hernández Uribe’s findings indicate that subduction was not an indispensable prerequisite for the formation of Archaean zircons.
Conversely, his research suggests that these minerals could have materialized under conditions of extreme pressure and elevated temperatures, stemming from the molten state of Earth’s substantial early crust.
“My analytical calculations and models demonstrate the capacity to replicate the characteristic signatures observed in zircons, even achieving a more precise alignment through the fractional melting of the lower crustal strata,” stated Dr. Hernández Uribe.
“Consequently, based on these outcomes, we lack sufficient empirical support to definitively ascertain the precise process responsible for continental genesis.”
The implications of these results also cast doubt upon the timeline for the commencement of plate tectonics on our planet.
Had Earth’s nascent continents emerged via subduction, it would imply that continental drift initiated between 3.6 and 4 billion years ago—as early as 500 million years after the planet’s inception.
Nevertheless, the alternative hypothesis, attributing the formation of primordial continents to crustal melting, suggests that subduction and tectonic activity may have commenced at a considerably later juncture.
“Our planet stands as a unique entity within the Solar System, exhibiting active plate tectonics as currently understood,” Dr. Hernández Uribe remarked.
“This phenomenon is intrinsically linked to the emergence of life, as the dynamics of early continental movement profoundly influenced atmospheric conditions, regulated oceanic chemistry, and established the foundational elements for life’s proliferation.”
This investigation received its formal publication on July 11, 2024, within the esteemed journal Nature Geoscience.
_____
D. Hernández-Uribe. Generation of Archaean oxidizing and wet magmas from mafic crustal overthickening. Nat. Geosci, published online July 11, 2024; doi: 10.1038/s41561-024-01489-z
This narrative is adapted from a press dissemination originating from the University of Illinois Chicago.
