The world’s largest iron ore deposits, nestled in Western Australia’s Hamersley Province, have a surprising origin story. A new study suggests these deposits formed during the dramatic breakup of the ancient supercontinent Columbia, approximately 1.4 billion years ago. This revelation challenges the previously held belief that these deposits were significantly older, dating back to 2.2 billion years ago.
The deposits reside within the Pilbara Craton, one of only two remaining pieces of Earth’s crust dating back to the Archaean Eon (3.8 to 2.5 billion years ago). The Pilbara Craton has witnessed the birth and demise of multiple supercontinents, offering valuable clues about the formation of the region’s mineral riches.
The researchers, led by Liam Courtney-Davies of the University of Colorado Boulder, focused on the breakup of Columbia, which existed between 1.7 and 1.45 billion years ago, followed by the amalgamation of Australia between 1.4 and 1.1 billion years ago. This tumultuous period, they propose, played a crucial role in the formation of the massive iron ore reserves in the Hamersley Province.
To pinpoint the age of the deposits, the researchers analyzed minerals in banded iron formations – towering blocks of sedimentary rock composed of alternating layers of iron oxides and iron-poor minerals. A novel geochronology technique, involving the analysis of uranium and lead isotopes within iron oxides, provided direct age measurements for the Hamersley Province deposits for the first time. These measurements revealed that the iron ore formation coincided with the breakup of Columbia, also known as Nuna, leading to the emergence of a primitive Australian continent.
The research team, including Martin Danisik of Curtin University in Australia, emphasized the link between tectonic events and the formation of these deposits. These events, spanning the entire Pilbara Craton, provided immense energy, forcing mineral-rich fluids from deep underground to create the massive iron ore deposits.
This groundbreaking research sheds light on ancient geological processes, revealing a connection between supercontinent cycles and the formation of iron ore deposits. This understanding holds promise for future exploration efforts, as geologists can now utilize these insights to predict the location of new iron ore deposits. Iron ore, a crucial ingredient in iron and steel production, is a sought-after resource for mining companies. The ability to predict the location of new deposits is a significant advancement in resource exploration, paving the way for future discoveries of this essential mineral.
