EAST LANSING, Michigan – September 4, 2026
Researchers at Michigan State University have discovered that iron deposits scattered across Earth's crust tell a richer story than previously understood, revealing how ancient mountain-building events and the spread of land plants fundamentally reshaped the planet's oxygen history.
Dalton Hardisty, the MSU Endowed Assistant Professor of Global Change Processes, led a team that analyzed iron records spanning 1.2 billion years of Earth's history. Their findings, published in the Proceedings of the National Academy of Sciences, suggest that iron formations once thought to track ocean oxygen levels alone actually reflect complex interactions between continents, atmosphere, and biological evolution.
Beyond Oxygen Tracking
For decades, geologists have used banded iron formations—layered sedimentary rocks rich in iron oxides—as markers for when Earth's oceans and atmosphere accumulated oxygen. The transition from pyrite (iron sulfide, commonly called "fool's gold") to hematite (iron oxide) in the rock record signaled this critical atmospheric shift.
But Hardisty's team found this interpretation was incomplete. "The iron that we were tracing was tracking more than changes in oxygen in the ocean, which is how the records were interpreted in the past," Hardisty said. "We didn't tear down the tool—we added another component to it to broaden the application and add new insight."
The analysis revealed two critical insights. First, continents themselves played a far more significant role in supplying iron to oceans than scientists had appreciated. Second, pyrite formed from continental iron supply mattered for Earth's oxygenation in ways earlier interpretations had missed.
Mountains and Iron Delivery
Looking at the oldest portions of the study, the researchers confirmed that traditional theories held: for billions of years, low-oxygen ocean conditions controlled iron records in sediments. But during the past 500 million years, a different mechanism took center stage.
The team discovered that peaks in iron records align closely with major mountain-building events. The Variscan mountain-building episode, which helped form the supercontinent Pangea, produced one of the most prominent peaks in the entire iron cycle record.
Plants Accelerated the Iron Cycle
Land plants fundamentally changed how iron moved through Earth's systems. Hardisty explained that plant roots release chemicals that break down rocks and sediments, freeing trapped iron. They also stabilize streambed sediments, giving iron more time to react with oxygen and form iron-oxide minerals that can be carried to oceans.
"Iron remains an important way to understand the past," Hardisty said. "Our findings will help researchers by expanding their tools to continue to study how climate change will affect the planet."
This biological acceleration means that once plants colonized land, they didn't just coexist with the iron cycle—they actively modified how iron moved across Earth's surface and into the oceans.
Implications for Climate Research
The discovery offers scientists a more nuanced framework for interpreting Earth's deep history, with implications that extend to understanding future environmental change. By understanding how iron cycling responded to past environmental shifts, researchers may better predict how Earth's surface processes respond to current climate warming.
The study's findings also clarify why different time periods show different patterns in the iron record. Early Earth's iron cycles were dominated by ocean chemistry. But as continents grew and plants appeared, the delivery mechanisms became increasingly important.
International Collaboration
The research involved scientists from the University of Hamburg in Germany and ETH Zurich in Switzerland, demonstrating how global scientific collaboration continues to refine our understanding of planetary systems. The team published their findings in the PNAS on September 4, 2026.
As climate researchers work to understand how Earth systems will respond to rising temperatures, these deep-time records offer valuable lessons. They show that surface processes, biological evolution, and atmospheric chemistry have been intimately connected for billions of years—and continue to shape our planet today.
Source: Proceedings of the National Academy of Sciences, September 4, 2026. Michigan State University Research News, September 4, 2026.
FIRAT Editorial Board
Institutional Research Desk · Foresight Institute of Research and Translation
The collective editorial and research translation board of FIRAT, synthesising peer-reviewed evidence, policy briefs, and division milestones across our seven foundational research pillars.
