Question

Match the rock types in Group-I with their most likely corresponding lithospheric / tectonic settings of formation in Group-II 
\[\begin{array}{|c|c|} \hline \textbf{Group I} & \textbf{Group II} \\ \hline \text{P. Boninite} & \text{1. Continental anorogenic} \\ \hline \text{Q. Lamproite} & \text{2. Island-arc} \\ \hline \text{R. Phonolite} & \text{3. Continental collision} \\ \hline \text{S. Leucogranite} & \text{4. Intraplate oceanic} \\ \hline \end{array}\]

• A. P-1, Q-3, R-4, S-2
• B. P-2, Q-4, R-1, S-3
• C. P-2, Q-1, R-4, S-3
• D. P-3, Q-2, R-1, S-4

Hint:

The tectonic setting of a rock formation helps in determining its mineral composition and geochemical signature, such as boninites being typical of island-arc settings.

Answer 1

The Correct Option is C

Let's analyze the relationship between rock types and tectonic settings:
- Boninite (P) is typically associated with island-arc settings, where subduction zones cause partial melting of the mantle. Boninites are high in magnesium and are found in oceanic arcs. Thus, P-2 is correct.
[6pt] - Lamproite (Q) forms in intraplate oceanic settings, often linked to mantle plumes. It is known for its potassium-rich composition. Therefore, Q-4 is correct.
[6pt] - Phonolite (R) is a volcanic rock that typically forms in continental collision zones, as a result of mantle melting and volcanic activity associated with the collision. Hence, R-1 is correct.
[6pt] - Leucogranite (S) is a light-colored granite that forms in continental anorogenic settings, often associated with the melting of the continental crust in stable continental regions. Thus, S-3 is correct.
Therefore, the correct match is (C): P-2, Q-1, R-4, S-3.