Distribution in Space and Time
The majority of ultramafic rocks are exposed in orogenic belts, and predominate in Archaean and Proterozoic terranes. Ultramafic magmas in the Phanerozoic are rarer, and there are very few recognised true ultramafic lavas in the Phanerozoic.
Many surface exposures of ultramafic rocks occur in ophiolite complexes where deep mantle-derived rocks have been obducted onto continental crust along and above subduction zones.
Read more about this topic: Ultramafic Rock
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