Question

On a fault surface with strike 320° and dip 55° NE, respectively, four sets of slickenslides were measured by a geologist. Given that the fault surface was measured correctly, the plunge and plunge direction of the lineation on the fault surface is

• A. 55° → 050°
• B. 20° → 320°
• C. 50° → 325°
• D. 60° → 090°

Hint:

To calculate the plunge and plunge direction of a lineation on a fault, use the strike and dip of the fault surface and apply stereographic projection or fault geometry principles.

Answer 1

The Correct Option is A

To solve this problem, we need to apply the basic principles of structural geology. The strike of the fault surface is 320°, and the dip is 55° NE. The slickenslides represent the direction of movement along the fault, and the plunge refers to the angle between the lineation (slickenslide) and the horizontal plane. The plunge direction is measured relative to the true north.
Given the fault surface's strike (320°) and dip (55° NE), we can calculate the plunge and plunge direction of the lineation using the appropriate stereographic projection or by using the geometry of the fault surface. The correct plunge angle and plunge direction based on the given information would be:
- Plunge = 55° (the angle between the lineation and the horizontal plane).
- Plunge direction = 050° (the direction of the plunge measured relative to north).
Thus, the correct answer is (A) 55° → 050°.