GENERAL GEOLOGY

GEOLOGY

PHYSICAL GEOLOGY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Foliation or lineation happens among deformed rocks due to
A
pressure and recrystallization of rocks
B
eruption of magma from the mantle to the crust
C
increase in temperature in the surrounding area
D
increase in volume of water as the rocks’ depth increases
Explanation: 

Detailed explanation-1: -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. hornblende) in this plane.

Detailed explanation-2: -Deformed rocks with foliation/lineation are brought by pressure and recrystallization of minerals. Pressure is the main factor of contact metamorphism Slate and gneiss are examples of foliated rocks.

Detailed explanation-3: -If they lie on a plane with mica, but with no common or preferred direction, this is foliation. If the minerals line up and point in a common direction, but with no planar fabric, this is lineation. When minerals lie on a plane AND point in a common direction; this is both foliation and lineation.

Detailed explanation-4: -Foliated Metamorphic Rocks: (Foliated means the parallel arrangement of certain mineral grains that gives the rock a striped appearance.) Foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned.

Detailed explanation-5: -As the minerals that form this foliation grow, they begin to break up the original beds into small pods. As the pods are compressed and extended, partly by recrystallization, they could eventually intersect again to form new compositional bands parallel to the new foliation.

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