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Neomorphism is considered coalescive when the recrystallization process involves either the formation of larger crystals in the place, and at the expense, of smaller crystal formations or the formation of smaller crystals within preexisting formations of crystals. Two types of coalescive neomorphism exist in petrology: aggrading neomorphism and ...
Dislocation creep is a non-linear (plastic) deformation mechanism in which vacancies in the crystal glide and climb past obstruction sites within the crystal lattice. [1] These migrations within the crystal lattice can occur in one or more directions and are triggered by the effects of increased differential stress.
Deformations are numbered according to their order of formation with the letter D denoting a deformation event. For example, D 1, D 2, D 3. Folds and foliations, because they are formed by deformation events, should correlate with these events. For example, an F 2 fold, with an S 2 axial plane foliation would be the result of a D 2 deformation.
In geology, texture or rock microstructure [1] refers to the relationship between the materials of which a rock is composed. [2] The broadest textural classes are crystalline (in which the components are intergrown and interlocking crystals), fragmental (in which there is an accumulation of fragments by some physical process), aphanitic (in which crystals are not visible to the unaided eye ...
In geology, solid-state recrystallization is a metamorphic process that occurs under high temperatures and pressures where atoms of minerals are reorganized by diffusion and/or dislocation glide. During this process, the physical structure of the minerals is altered while the composition remains unchanged.
This results in a banded, or foliated, rock, with the bands showing the colors of the minerals that formed them. Foliated rock often develops planes of cleavage . Slate is an example of a foliated metamorphic rock, originating from shale , and it typically shows well-developed cleavage that allows slate to be split into thin plates.
These rocks are fine-grained and sometimes cool so rapidly that no crystals can form and result in a natural glass, such as obsidian, however the most common fine-grained rock would be known as basalt. Any of the three main types of rocks (igneous, sedimentary, and metamorphic rocks) can melt into magma and cool into igneous rocks. [2]
Layers of rock that fold into a hinge need to accommodate large deformations in the hinge zone. This results in voids between the layers. These voids, and especially the fact that the water pressure is lower in the voids than outside of them, act as triggers for the deposition of minerals.