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Merohedral twinning occurs when the lattices of the contact twins superimpose in three dimensions, such as by relative rotation of one twin from the other. [8] An example is metazeunerite. [9] Contact twinning characteristically creates reentrant faces where faces of the crystal segments meet on the contact plane at an angle greater than 180°. [3]
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
Pericline also refers to a doubly plunging anticline or syncline.. Pericline is a form of albite exhibiting elongate prismatic crystals. [1]Pericline twinning is a type of crystal twinning which show fine parallel twin laminae typically found in the alkali feldspars microcline. [2]
Twinning (making a twin of) may refer to: In biology and agriculture, producing two offspring (i.e., twins) at a time, or having a tendency to do so; In engineering and manufacturing, the creation of a digital twin or the synching of such twins; Twinning (cooperation) Afri Twin, an exchange partnership between schools in the United Kingdom and ...
Shock metamorphism or impact metamorphism describes the effects of shock-wave related deformation and heating during impact events.. The formation of similar features during explosive volcanism is generally discounted due to the lack of metamorphic effects unequivocally associated with explosions and the difficulty in reaching sufficient pressures during such an event.
In geology, a stock is an igneous intrusion that has a surface exposure of less than 100 square kilometres (40 sq mi), [1] [2] differing from batholiths only in being smaller. A stock has a discordant relationship with the rocks that it intrudes. Many stocks are cupolas of hidden batholiths.
In 1992, Coffin and Eldholm initially defined the term "large igneous province" as representing a variety of mafic igneous provinces with areal extent greater than 100,000 km 2 that represented "massive crustal emplacements of predominantly mafic (magnesium- and iron-rich) extrusive and intrusive rock, and originated via processes other than 'normal' seafloor spreading."
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