Where is troctolite found?
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, the Duluth Complex of the North American Midcontinent Rift, and the Tertiary …
How is troctolite formed?
The genesis of troctolite is also strongly tied to gabbro. These two rocks usually occur together in the same magma intrusion because troctolite can not form directly as magma crystallizes. There is no way how magma can crystallize into olivine and plagioclase without pyroxene.
What is a Gabbronorite?
Gabbronorite is a mafic composed of the calcium-rich plagioclase and hypersthene, olivine can be present in small quantities. The name gabbronorite is derived the Norwegian name for Norway, Norge.
What is Picrite rock?
picrite, intrusive igneous rock of ultramafic (very silica-poor) composition that is composed largely of olivine and augite and is somewhat similar to peridotite. Picrites are dark, heavy rocks and contain a small but variable amount of plagioclase feldspar; hornblende and biotite may also be present.
What type of rock is Troctolite?
troctolite, coarse-grained, intrusive igneous rock that is composed almost entirely of olivine (often iron-rich) and plagioclase feldspar (labradorite or bytownite).
What might be the origin of a rock composed entirely of olivine?
The origin of a rock composed almost entirely of olivine would be from a magma that is at high temperature and is enriched in iron and magnesium. The olivine-rich rock likely formed by fractional crystallization early on in the cooling process.
What type of rock is troctolite?
Troctolite is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with minor pyroxene. It is an olivine-rich anorthosite, or a pyroxene-depleted relative of gabbro. However, unlike gabbro, no troctolite corresponds in composition to a partial melt of peridotite.
What is the genesis of troctolite?
The genesis of troctolite is also strongly tied to gabbro. These two rocks usually occur together in the same magma intrusion because troctolite can not form directly as magma crystallizes. There is no way how magma can crystallize into olivine and plagioclase without pyroxene.
Is troctolite a gabbro?
It is an olivine-rich anorthosite, or a pyroxene-depleted relative of gabbro. However, unlike gabbro, no troctolite corresponds in composition to a partial melt of peridotite. Thus, troctolite is necessarily a cumulate of crystals that have fractionated from melt.
What type of rock is speckled like trout?
Click the show button to view. A gabbroid with <5% pyroxene and is composed chiefly of calcic plagioclase (e.g., labradorite) and olivine. Such rocks commonly are speckled like trout. This section is currently hidden.
