Question

Based on the given schematic ternary phase diagram, choose the correct statement(s). 

• A. Point 1 is the thermal minimum in the system.
• B. The diopside – albite join acts as a thermal barrier in the system.
• C. Point 2 and 3 are ternary eutectics.
• D. Melt of composition X will give rise to a rock containing nepheline + albite.

Hint:

In ternary phase diagrams, understanding the thermal minimum and eutectic points is crucial for interpreting the stability and composition of minerals in a rock.

Answer 1

The Correct Option is B, C, D

Step 1: Understanding the Ternary Phase Diagram.
The ternary phase diagram shows the phases and reactions that occur at different compositions in a three-component system. The diagram contains information about the thermal behavior, eutectic points, and composition of melts formed in the system.
- Point 1 is the thermal minimum because it corresponds to the lowest temperature at which the system remains stable (A).
- The diopside-albite join acts as a thermal barrier, meaning it prevents certain phases from forming due to the specific chemical interaction between diopside and albite (B).
- Points 2 and 3 are eutectic points, where the system forms multiple solid phases at the same temperature (C).
- The melt at composition X will result in a rock consisting of both nepheline and albite, as shown by the intersection of the line through point X with the nepheline and albite phases (D).
Step 2: Conclusion.
The correct answers are (A), (B), and (D).