The rise of Earth’s continents

An illustration of the Snowball Earth. Depositphotos.

This seminal study, which has sent shockwaves through the geological community, offers a tantalizing glimpse into a world previously obscured by misconceptions and raises the curtain on a new era of fresh insights into our planet's geological makeup.

A recent study by scientists from Cornell and the Smithsonian Institution dismantles a popular hypothesis on Earth’s continental crust composition, opening doors to fresh geological insights, and reveals the rise of Earth’s continents.

Garnet Hypothesis Disproved: The Rise of Earth’s Continents

Researchers from Cornell and the Smithsonian Institution discredited a widely accepted hypothesis on the contrasting compositions of Earth’s continental and oceanic crusts. The study, published on May 5 in Science, enriches our grasp of Earth’s continental geology.

Laboratory Experiments and X-ray Spectroscopy Unravel the Truth

Megan Holycross, a Cornell Engineering professor, and Elizabeth Cottrell, a Smithsonian research geologist, led the study. They used lab experiments to show that garnet crystallization isn’t behind Earth’s continental crust’s iron-depleted, oxidized chemistry. This unique composition helps create dry land, enabling terrestrial life.

Recreating Magma Chamber Conditions

Holycross and Cottrell crafted garnet samples from molten rock. They simulated the intense pressure and heat found beneath continental arc volcanoes. The team also gathered analyzed garnets from the Smithsonian’s National Rock Collection and researchers worldwide as reference materials.

Advanced Techniques Uncover Garnet Secrets

The scientists took their materials to the U.S. Department of Energy’s Argonne National Laboratory. They used high-energy X-ray beams and X-ray absorption spectroscopy to study the garnets. This method reveals a material’s structure and composition based on X-ray absorption.

New Findings Challenge Established Beliefs

The results indicated that the garnets hadn’t absorbed enough unoxidized iron from rock samples to explain iron depletion and oxidation in magmas. The researchers concluded that the garnet crystallization model is unlikely to account for oxidized, iron-depleted magmas from continental arc volcanoes.

Exploring Alternate Explanations for Oxidation

Holycross acknowledged the study adds to our understanding but leaves questions unanswered. Future research will investigate possible causes of iron oxidation in magmas, such as the transfer of an oxidizing agent from subducting material beneath continental magma chambers.

Have something to add? Visit Curiosmos on Facebook. Join the discussion in our mobile Telegram group.