Question

Arrange the following in progressive sequence of the Barrovian zones:
A. Biotite zone,
B. Staurolite zone,
C. Kyanite zone,
D. Garnet zone, E. Chlorite zone. Choose the correct answer from the options given below:

• A. A, B, C, D, E
• B. E, A, D, B, C
• C. E, B, D, C, A
• D. B, C, E, D, A

Hint:

Barrovian zones progress as Chlorite \(\rightarrow\) Biotite \(\rightarrow\) Garnet \(\rightarrow\) Staurolite \(\rightarrow\) Kyanite.

Answer 1

The Correct Option is B

Concept:
Barrovian metamorphic zones show progressive regional metamorphism. They are arranged from low grade to high grade according to index minerals.

Step 1: Lowest grade zone.
Chlorite zone represents the lowest grade Barrovian metamorphic zone. \[ \text{Lowest}=E \]

Step 2: Next zone.
After chlorite zone comes biotite zone. \[ \text{Second}=A \]

Step 3: Intermediate zones.
After biotite zone comes garnet zone, then staurolite zone. \[ D>B \]

Step 4: Higher grade zone.
Kyanite zone represents higher grade metamorphism among the given zones. \[ \text{Highest}=C \] Therefore, the progressive sequence is: \[ \text{Chlorite}\rightarrow \text{Biotite}\rightarrow \text{Garnet}\rightarrow \text{Staurolite}\rightarrow \text{Kyanite} \] Using letters: \[ E>A>D>B>C \] \[ \therefore \text{Correct Answer is (B)} \]