What Does Lineation Mean In Structural Geology?


1 Answers

Shumaela Rana Profile
Shumaela Rana answered
Lineation is the sub parallel to parallel alignment of elongate linear fabric elements in a rock body, commonly penetrative at the outcrop scale or at the hand specimen scale of observation. It is a unidirectional structure as name implies and is measured by the plunge and the trend. This penetrating feature is commonly present at microscopic scale. Some lineation is primary produced in sediments, lava or magma prior to the lithification.
Examples of the lineation may include; parting lineation in silt stone and sand stone, the cherts of ripple marks form primary lineation at the time of deposition, lineations in the lava is ropy lava (basaltic flow), feldspar can form foliation as well as lineation.
The three types of the lineation are as under:

1) Cranulation lineation.
All hinge lines of minor folds form the cranulation lineation. The controlling factor is folding of pre existing lineation.
2) Intersection lineation.
When any two planar structures intersect they form a linear structure called intersection lineation. For example the intersection of cleavage surfaces and bedding planes.
3) Stretched mineral lineation.
The certain acicular minerals under forces effect like hornblende are arranged in one direction forming linear structure. Sometimes large minerals change to smaller ones forming this lineation.

Answer Question