Northern Miner
The earth has many unique ways of stripping base metals from its crust and concentrating them into deposits. Over the course of civilization, humans have uncovered seven main types: sediment-hosted copper-cobalt, magmatic nickel-copper-platinum group metal; volcanogenic massive sulphide; porphyry; mississippi valley type; sediment exhalative; and laterites.
Sediment hosted copper-cobalt deposits
The majority of world-class sediment hosted copper-cobalt deposits formed shortly after a unique period of time often referred to as the “Boring Billion,” the “Earth’s Middle Ages”, or “the Dullest Time on Earth”. The earth’s major landmasses combined to form one large supercontinent, and remained relatively stable, positioned along warmer latitudes, from 1.7 billion to 750 million years.
The continent began to break apart in the neo-Proterozoic, but many of the rifts failed, becoming significant basins of evaporitic, lacustrine and red-bed sediments mixed with saline and oxidized fluids called brines. The brines circulated through the basins for tens, if not hundreds of millions of years, stripping metals from the rocks only to redeposit them onto chemically reductive horizons.
The sheer size and scale of the mineralizing process created blankets of high-grade copper that extend for tens of kilometres in scale, and account for 20% of the world’s copper production today. Supergiant examples are found within the Kodaro-Udokan basin of Siberia, the Katangan basin of south-central Africa, and the Zechstein basin of northern Europe.
As an example of a world-class deposit, Ivanhoe Mines (TSX: IVN; US-OTC: IVPAF) Kamoa and Kakula deposits in the Katangan belt hosts a combined 1.4 billion indicated tonnes of 2.64% copper, and 316 million inferred tonnes of 1.76% copper over a 4.5 to 6.9-metre thickness.
Magmatic nickel-copper-PGM deposits
Magmatic nickel-copper-platinum group metals (PGM) deposits occur when magnesium-rich magma (called ultramafics) sourced from the mantle, break through the crust in a dense network of dykes, sills and magma chambers.
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