It is a late-stage magmatic mineral, formed in the residual melt of mafic layered intrusions in either the olivine-chromite, pyroxene, or plagioclase-rich layers.
22.
Radiometric dating shows that the Wyoming province's Blue Draw Metagabbro was undergoing rifting at, the same time the emplacement of the long belt of mafic layered intrusions in the Sudbury region.
23.
Rarer intermediate composition and mafic pegmatites containing amphibole, Ca-plagioclase feldspar, pyroxene, feldspathoids and other unusual minerals are known, found in recrystallised zones and apophyses associated with large layered intrusions.
24.
However, the story is not so simple, because most ultramafic-mafic layered intrusions also correlate with craton margins, perhaps because they are exhumed more efficiently in cratonic margins because of faulting and subsequent orogeny.
25.
Norite occurs with gabbro and other mafic to ultramafic rocks in layered intrusions which are often associated with platinum orebodies such as in the Bushveld Igneous Complex in South Africa, the Gombak norite in Bukit Batok, Singapore.
26.
The classic example of a Proterozoic layered intrusion with cumulate harzburgite is the Stillwater igneous complex of Montana, U . S . A . It is also found in the Bushveld Igneous Complex, a large layered intrusion in South Africa.
27.
The classic example of a Proterozoic layered intrusion with cumulate harzburgite is the Stillwater igneous complex of Montana, U . S . A . It is also found in the Bushveld Igneous Complex, a large layered intrusion in South Africa.
28.
Troctolite is found in some layered intrusions such as in the Archean Windimurra intrusion of Western Australia, the Voisey's Bay nickel-copper-cobalt magmatic sulfide deposit of northern Labrador, the Stillwater igneous complex of Montana and the Tertiary Rhum layered intrusion of the island of R�m, Scotland.
29.
Troctolite is found in some layered intrusions such as in the Archean Windimurra intrusion of Western Australia, the Voisey's Bay nickel-copper-cobalt magmatic sulfide deposit of northern Labrador, the Stillwater igneous complex of Montana and the Tertiary Rhum layered intrusion of the island of R�m, Scotland.
