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STRUCTURAL GEOLOGY LAB. STEREOGRAPHIC PROJECTION Dr. Masdouq Al-Taj. STEREOGRAPHIC PROJECTION Stereographic Projection is a method of representing and interpreting orientational data (such as the dip of bedding plane or joint trace). What can stereographic projection be used for?
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STRUCTURAL GEOLOGY LAB.STEREOGRAPHIC PROJECTIONDr. Masdouq Al-Taj
STEREOGRAPHIC PROJECTION Stereographic Projection is a method of representing and interpreting orientational data (such as the dip of bedding plane or joint trace).
What can stereographic projection be used for? • Representing inclined beds. • Representing joint traces and fractures. • Solving apparent dip and true dip problems. • Determining Pole to plane. • Determine the attitude Rake (Pitch) on planes. • Determine the attitude Intersection of two planes - Determine the attitude of Fold axis
Overlay sheet * A sheet of tracing paper is placed over the stereo net. * Mark the Primitive circle, the north, the east, the south, and the west.
1. Plotting a Plane -Mark off the strike of the plane on the circumference of the stereonet
* Rotate the overlay so that the strike line is north-south. * Count in the dip angle along the equator from the East or West ( here, from E).
* Trace the appropriate great circle. * It may happen that the great circle you need to plot does not coincide with a plotted great circle, in that case interpolate between the two nearest plotted circles.
2. Plotting a line Line: plunge 30 trend 270
2. Plotting a line * Count off the trend around the circumference of the stereonet and mark it.
* Rotate the overlay so the trend lies along (E-W line for example).
* Count in along the E-W line and plot the point at the appropriate plunge.
On a vertical face striking 285º (F1), the apparent dip of bedding (S) pitches 23º W. on a second vertical face (F2) striking due north the apparent dip of S pitches 16º S. What is the strike and dip of S.?
Plot the following plane and the line lying within it. Work out the trend and plunge of the line. a-plane strike 30º, dip 45º W, line pitches 30º N.
4. Angles between lines on a plane Plane 0/50 E Rake 62 N or Line1: P50 Line2: Rake 80 S or T110 P 50
5. Determine the angle between two planes
A vein (V) striking 342º and dipping 16º SW intersects a fault (F) striking 70º and dipping 45º S. What is the trend and plunge of the line of intersection of F and V?
6. Determine the attitude of intersection between two planes