'620-mile fault mystery': Scientists uncover tectonic secrets beneath Alaska’s terrain

Produced by: Mohsin Shaikh

Fault enigma

Beneath Alaska lies the Denali Fault, a 620-mile mystery that has puzzled geologists for decades, now revealed as the key to ancient tectonic events.

Unified history

Sean Regan’s research uncovers how three regions—Clearwater Mountains, Kluane Lake, and Coast Mountains—once formed a single suture zone on North America’s plate.

Credit: Wikimedia Commons

Inverted puzzle

Inverted metamorphism in these regions reveals rocks formed at great depths now lie above shallower ones, offering clues to tectonic activity.

Plate fusion

The Wrangellia Composite Terrane, an ancient oceanic plate, fused with North America 72 million years ago, driven by massive tectonic forces.

Credit: Wikimedia Commons

Dynamic shifts

Over millions of years, strike-slip movements along the Denali Fault tore the unified suture zone apart, scattering fragments across hundreds of miles.

Critical insights

Monazite analysis helped Regan’s team trace temperature and pressure changes, confirming a shared history of these regions under identical conditions.

Seismic risks

The Denali Fault remains active today, capable of triggering powerful earthquakes, shaping Alaska’s rugged landscape.

Decades untangled

Building on a 1993 study, Regan’s findings combine modern techniques and historical data to reconstruct the Denali Fault’s tectonic story.

Global lessons

This study provides a model for understanding how continents evolve and offers a framework for studying similar fault systems worldwide.

Credit: Wikimedia Commons