Question

The transformation of Limestone into Marble is an example of which type of metamorphism?

• A. Contact metamorphism
• B. Regional metamorphism
• C. Dynamic metamorphism
• D. Hydrothermal metamorphism

Hint:

Limestone + Heat (magma) $\rightarrow$ Marble Think: \textbf{Heat nearby = Contact metamorphism}.

Answer 1

The Correct Option is A

Concept: Metamorphism refers to the alteration of pre-existing rocks due to changes in temperature, pressure, and chemical environment without melting. Different types of metamorphism are classified based on the dominant factors:

• Contact metamorphism: Caused mainly by high temperature due to nearby magma intrusion.
• Regional metamorphism: Occurs over large areas under high pressure and temperature (mountain building).
• Dynamic metamorphism: Associated with fault zones and high shear stress.
• Hydrothermal metamorphism: Involves chemical alteration by hot fluids.

Limestone is primarily composed of calcium carbonate \((CaCO_3)\). When subjected to high temperatures, its minerals recrystallize to form marble, a denser and more crystalline rock. Step 1:Identify the parent and resulting rock.
Limestone (sedimentary rock) transforms into marble (metamorphic rock).
Step 2:Determine the dominant metamorphic factor.
This transformation mainly occurs due to heat from nearby magma bodies, rather than intense pressure over large areas.
Step 3:Match with the correct metamorphism type.
Such localized heating around igneous intrusions is characteristic of contact metamorphism.
Step 4:Eliminate other options.

• Regional metamorphism involves large-scale pressure and temperature changes.
• Dynamic metamorphism is related to faulting and deformation.
• Hydrothermal metamorphism involves fluid interaction rather than simple recrystallization.

Step 5:Conclude the answer.
Thus, the transformation of limestone into marble is an example of contact metamorphism.