Question

The most important factors for the development of foliation in metamorphic rocks are:

• A. Chemically active fluids and stress
• B. Temperature and chemically active fluids
• C. Lithostatic pressure and temperature
• D. Stress and temperature

Hint:

Foliation develops mainly due to directed stress and recrystallization during metamorphism.

Answer 1

The Correct Option is D

Concept:
Foliation is the planar arrangement of minerals in metamorphic rocks.

Step 1: Role of stress.
Directed stress causes platy and elongated minerals to align perpendicular to maximum compression. \[ \text{Directed stress} \Rightarrow \text{preferred mineral orientation} \]

Step 2: Role of temperature.
Temperature helps minerals recrystallize during metamorphism. \[ \text{Temperature} \Rightarrow \text{recrystallization} \]

Step 3: Final answer.
Thus, stress and temperature are the most important factors for foliation development. \[ \therefore \text{Correct Answer is (D)} \]