Class 16 Drill Section Exercise
Objectives:
Part 1: Construct an east-west drill section from the data in the drill logs in Data Sheet DS5.Part 2: Calculate the true thickness of the Charles Vein.Part 3: Plot an inclined drill hole using the apparent dip.Part 4: Determine the depth necessary to drill to intersect the Victoria Vein.
Procedure:
Part 1: Construct the drill section as follows:
1. Use a ruler to measure and draw vertical lines downward from the collar locations,shown by small x’s. Make the lines the appropriate length (the scale is 1’ = 100 FT).
2. Draw a short perpendicular line across the bottom of the drill hole line. Label the bottom of the drill hole with the total depth (TD = ).
3. Use a thick black line to highlight the intercepts (range) containing gold values above 0.8 opt (ounces per ton). Note that DH1 has intersects both the Victoria and Charles Veins, and DH2 only intersects the Charles Vein. The intercepts represent the “apparent thicknesses” of the veins.
4. Label the intercepts with the footage range (for example: 50 90 FT) and the average grade (average the four values for the high grade intercept) for each of the high grade vein intercepts.
| Example: | 30 70 ‘: |
| 40 ‘ @ 2.2 opt |
5. Draw a smooth line connecting the top of the Charles Vein in DH1 with the top of the Charles Vein in DH2. Draw another smooth line connecting the bottom of the Charles Vein intercepts.
6. Use shading to illustrate the sericite alteration halo adjacent to the vein. Refer to the drill logs to determine the apparent thickness of the halo.
Part 2: Determine the true thickness of the Charles Vein in DH 2 as follows:
1. Use a protractor to measure the dip of the Charles Vein.
2. Use trigonometry to determine
the true thickness (thickness taken perpendicular to the vein walls)
of the Charles Vein, as follows:
a) Draw a right triangle such that the hypotenuse corresponds to the vein intercept (apparent thickness)(side “b” of the triangle).
b) Determine the angle between the drill hole and the vein by subtracting the dip angle of the drill hole from 90.
c) Multiply the sin of this angle times the hypotenuse (ie, apparent thickness). This result is the length of side “a” of the triangle, which is the true thickness of the Charles Vein.
1. DH 3 is an angle hole with a bearing of 45 and a true dip of 75 O, and a total depth of 405 feet.
2. Determine the angle between the drill section line and the strike direction (perpendicular to the bearing).
3. Look up the value of the apparent dip in Table 16 - 1.
4. Draw a line representing DH3 on the drill section, and using the apparent dip value.
5. Use the scale to make the line the correct length.
Part 4: Determine the depth needed to drill to intersect the Victoria Vein if the drill is located at an easting of 200 E.
1. Look at your drill section at 200 E. Draw a line down from the collar location to represent proposed drill hole DH 4.
2. Use the scale to draw a vertical line representing proposed drill hole DH 4. The line should extend from the surface collar location downward just past the Victoria Vein. Use the scale to measure the length of the line, to the nearest tenth of an inch, which intersects the Victoria Vein..
Downlad Drill Log and Drill Section in PDF format.
