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In Precambrian: Sedimentary basins, basic dikes, and layered complexes
The Stillwater Complex is a famous, 2.7-billion-year-old, layered ultrabasic-basic intrusion in the Beartooth Mountains of Montana in the United States. It is 48 km (30 miles) long and has a stratigraphic thickness of 6 km (3.7 miles). It was intruded as a subhorizontal body of magma…
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In Precambrian: Archean crustal growth
…igneous complexes (such as the Stillwater in Montana) formed; and the formation of the first large sedimentary basins (for example, the Witwatersrand in South Africa) also occurred. All of these structures indicate that the continental crust had reached a mature stage with considerable stability and rigidity for the first time…
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In mineral deposit: Immiscible melts
…the world’s platinum-group metals; the Stillwater Complex, Montana, host to platinum-group deposits similar to the Merensky Reef; and the Norilsk deposits of Russia, containing large reserves of platinum-group metals.
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In platinum group: Ores
…the largest deposit is the Stillwater Complex in Montana, but this is substantially smaller than the deposits cited above. The world’s largest producers of platinum are South Africa, Russia, Zimbabwe, and Canada.
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