What is the difference between foliation and lineation in a metamorphic rock?
What is the difference between foliation and lineation in a metamorphic rock?
Foliation is the result of the parallel arrangement of (micas, etc.) in a plane perpendicular to the maximum principal applied stress. A lineation is caused by a similar growth of elongate minerals (eg. Slate, schist, and gneiss are three common foliated metamorphic rocks.
What is foliation in a metamorphic rock?
Foliated Metamorphic Rocks: Foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that pressure was applied.
What is lineation in metamorphic rock?
A lineation is any linear feature or element in a rock , and can occur as the product of tectonic, mineralogical, sedimentary, or geomorphic processes. Lineations are the one-dimensional counterparts of foliations, and both are part of the fabric (geometric organization of features) of a rock.
What causes foliation and banding in metamorphic rocks?
Foliation is produced in a rock by the parallel alignment of platy minerals (e.g., muscovite, biotite, chlorite), needle-like minerals (e.g., hornblende), or tabular minerals (e.g., feldspars). Foliation is common in aphanitic as well as phaneritic metamorphic rocks. Some foliated rocks are also banded.
Is foliation a lineation?
Foliations and lineations are primary if they orig- inate by primary sedimentary or igneous processes. Pri- mary sedimenrary processes such as sediment transport and deposition produce, for example, linear tool marks, thc preferred orientation of sedimentary clasts, and bed- ding.
What is intersection lineation?
Intersection lineations are linear structures formed by the intersection of any two surfaces in a three-dimensional space. Intersection lineations can also be due to the intersection of two foliations. Intersection lineations are measured in relation to the two structures which intersect to form them.
What is foliated and Nonfoliated metamorphic rocks?
Foliated metamorphic rocks such as gneiss, phyllite, schist and slate have a layered or banded appearance that is produced by exposure to heat and directed pressure. Non-foliated metamorphic rocks such as hornfels, marble, quartzite and novaculite do not have a layered or banded appearance.
How will foliation in continental metamorphic rocks formed during subduction be oriented?
Pre-existing rock is altered through heat and pressure. How will foliation in continental metamorphic rocks formed during subduction be oriented? Perpendicular to the direction of plate movement.
Why is Lineation used?
Lineation is one of many devices poets use to emphasize or subordinate meaning, to orchestrate ambiguities, and to encourage the interpretations they desire while closing off unwanted avenues. Lineation shapes readers’ involvement in and understanding of a poem.
What is meant by Lineation?
Definition of lineation 1a : the action of marking with lines : delineation. b : outline. 2 : an arrangement of lines.
What is meant by lineation?
Which is an example of a foliation in a rock?
Alignment of tabular minerals in metamorphic rocks, igneous rocks and intrusive rocks may form a foliation. Typical examples of metamorphic rocks include porphyroblastic schists where large, oblate minerals form an alignment either due to growth or rotation in the groundmass.
Which is an example of a lineation in rock?
Lineation • The word lineation is used to describe any linear structure that occurs repetitively in a sample of rock; for example, it may refer to an array of elongate pebbles, oriented with their long dimensions mutually parallel, or it may refer to the lines of intersection of two foliation. Diorite gneiss. 6. Contd..
How is slate a metamorphic Foliated rock?
Slate is a fine-grained, foliated metamorphic rock that is physically and chemically changed (mineral grains changed directions) through by the alteration of shale or mudstone by low-grade regional metamorphism. (https://www.radford.edu/jtso/GeologyofVirginia/Rocks/GeologyOfVARocks2-5a.html)
What causes mica to grow in a foliation?
Thermal metamorphism in the aureole of a granite is also unlikely to result in growth of mica in a foliation, although growth of new minerals may overprint existing foliation (s). Alignment of tabular minerals in metamorphic rocks, igneous rocks and intrusive rocks may form a foliation.