The gigantic iron ore deposit in Hamersley Province, located in Western Australia, was formed during major tectonic events that led to the breakup of the ancient supercontinent Columbia.
The largest iron ore deposit in the world was formed when the ancient supercontinent Columbia broke apart approximately 1.4 billion years ago, according to a study published in the journal PNAS, as reported by Live Science on August 1. The mine, located in Hamersley Province, today sits atop a crustal plate known as the Pilbara Craton. The Pilbara Craton is one of only two known crustal fragments dating back to the Paleoarchean Era (2.5 to 3.8 billion years ago), containing some of the oldest rock types on the planet. The other crustal fragment from this era is the Kaapvaal Craton in southern Africa.
A 1.3 billion year old iron core from Hamersley Province. (Photo: Liam Courtney-Davies).
The rocks in the Pilbara Craton have witnessed the birth and breakup of several supercontinents, meaning they hold clues about the origins of the region’s rich mineral deposits. In particular, the breakup of the supercontinent Columbia, which existed between 1.45 and 1.7 billion years ago, and the subsequent amalgamation into the continent of Australia from 1.1 to 1.4 billion years ago, may explain how the vast iron ore deposit formed in Hamersley Province.
“The energy from geological activity likely drove the production of billions of tons of iron-rich rock across Pilbara,” said lead researcher Liam Courtney-Davies, a geochronologist at the University of Colorado, Boulder.
Hamersley Province contains over 55 billion tons of iron ore, which geologists previously believed formed around 2.2 billion years ago. However, based on direct dating techniques, the new study found that the deposit is actually much younger, forming between 1.1 and 1.4 billion years ago.
To determine the age of the deposit, Courtney-Davies and colleagues dated minerals in eight iron-rich formations, large sedimentary rock bodies containing layers of iron oxides like magnetite and hematite, along with iron-poor minerals such as chert. The research team utilized a new geochronological technique that involved analyzing uranium and lead isotopes within the iron oxides of the rocks, allowing them to measure the deposit’s age directly.
The measurements revealed that the iron ore formed around the same time the supercontinent Columbia, also known as Nuna, was breaking apart, leading to the formation of the primordial continent of Australia, according to co-author Martin Danisik, an associate professor of geology at Curtin University, Australia.
Tectonic events across the Pilbara Craton provided the necessary energy and pushed mineral-rich fluids from deep within the Earth to form the ore deposit. This new discovery could help geologists identify other potential ore deposits in the future. Iron ore is a crucial component in the production of iron and steel. Therefore, many resource extraction companies are continually searching for new iron ore deposits that can be exploited.
