Question

Which of the following statements is/are CORRECT for the M-plane of any fault?

• A. M-plane pole of a fault is located on the fault plane
• B. M-plane pole of a fault is perpendicular to the slickenline on the fault plane
• C. M-plane pole of a fault is parallel to the slickenline on the fault plane
• D. M-plane pole of a fault is perpendicular to the pole to the fault plane

Hint:

- Fault plane → contains slip line (slickenline).
- M-plane → perpendicular to fault plane, contains slip line.
- M-plane pole → lies on fault plane, perpendicular to slickenline, and perpendicular to the pole of the fault plane.

Answer 1

The Correct Option is A, B, D

Step 1: Understanding the M-plane.
In fault-slip analysis, the M-plane (movement plane) is defined as the plane that contains the slip direction (slickenline) and is perpendicular to the fault plane. Its pole is an important construct used in kinematic analysis of faults.
Step 2: Evaluating each statement.
- (A) M-plane pole of a fault is located on the fault plane.
Since the M-plane is defined relative to the fault plane and its orientation is constrained by slip on the plane, its pole lies on the fault plane.
- (B) M-plane pole of a fault is perpendicular to the slickenline on the fault plane.
By definition, the M-plane pole lies at right angles to the slip lineation within the fault plane.
- (C) M-plane pole of a fault is parallel to the slickenline on the fault plane.
This is the opposite of the true relation — it is perpendicular, not parallel.
- (D) M-plane pole of a fault is perpendicular to the pole to the fault plane.
The pole to the fault plane is normal to the plane, and the M-plane pole lies orthogonal to it.
Step 3: Final Answer.
Thus, the correct statements are: \[ \boxed{\text{(A), (B), and (D)}} \]