High-Grade Iron Ore Exploration in an Increasingly Steel-Hungry World: The Past, Current, and Future Role of Exploration Models and Technological Advances
Hilke Dalstra, Marcus Flis, 2008. "High-Grade Iron Ore Exploration in an Increasingly Steel-Hungry World: The Past, Current, and Future Role of Exploration Models and Technological Advances", Banded Iron Formation-Related High-Grade Iron Ore, Steffen Hagemann, Carlos Alberto Rosière, Jens Gutzmer, Nicolas J. Beukes
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Earliest discoveries of iron ore basins worldwide were commonly the result of regional, government-instigated surveys. After initial discovery, exploration for high-grade iron ores within these basins used ore genesis models from a very early stage. These models included syngenetic, hypogene, and supergene concepts. Systematic prospecting using a supergene genetic model with stratigraphic and structural contributions was hugely successful in identifying major resources in the Hamersley province at an early stage, but the use of this model resulted in significant underestimation of the size of some deposits. With detailed drilling and mining of deposits, many features which seemed at odds with a simple supergene origin were discovered, and modified supergene-metamorphic, syngenetic, or hypogene models were proposed. It was the recognition in these models that high-grade hematite ores could occur concealed beneath unmineralized iron formation that initiated a concealed orebody search by Hamersley Iron from 1980 to 1994. The concealed orebody search was modeled on the CSIRO supergene-metamorphic model. This was followed by a dedicated high-grade hematite search following hypogene concepts by the Hamersley Iron Task Force from 1994 to 2001. These programs were successful in identifying semiconcealed high-grade hematite ores, but none led to a major discovery to replace the Mount Tom Price deposit. Before the concealed orebody search and the Task Force, very limited exploration using a syngenetic model had been carried out at Paraburdoo, which resulted in discovery of the largely concealed Lens 2 deposit.
Worldwide, models for the formation of high-grade hematite ores are being refined due to current global exploration activity, which is resulting in greatly improved understanding of the geology of deposits and iron ore provinces. Exploration models are shifting from supergene to hypogene, which has led to deeper drilling and discovery of significant additional resources in some areas. Modern academic and exploration techniques are refining the current ore genesis models and together with the availability of new geophysical methods provide the iron ore exploration geologists with an invaluable set of tools to discover the future, most likely concealed hematite, deposits to satisfy the world's ever-increasing hunger for iron ore.