Archean Au-Ag-(W) quartz vein/disseminated ... - Geology Ontario

12.3. Quartz Vein Area
Figure 57 shows the changes in total area (calculated as described above) occupied by major
(^.3 m width) quartz veins relative to the area value on the 5600 ft level. The diagram shows
the following:
(i) No change in the total area of quartz veining occurs between the 5600 ft and 4800 ft levels,
indicating that expansion of the vein system upwards had not yet begun at these levels and
suggesting that these may be the characteristics of the feeder zone.
(ii) Quartz veining expands upwards ~6" times in total area between the 4800 ft and 2800 ft
levels (a vertical interval of-600 m); this inflation corresponds closely with the expansion
of green carbonate alteration (see Figure 56), and correlates satisfactorily with the onset of
economic Au mineralisation in the root zone of the green carbonate ore (#14 orebody) on
the 4000 ft level (see longitudinal, Figure 28); by this level, the areal expansion of quartz
veining has reached ~3 times the value on the 4800 ft and 5600 ft levels.
(Hi) The area of quartz veining remains approximately constant (~6-8 times the value on the
5600 ft level) in the mid- and upper levels of the mine between the 2800 ft and 850 ft levels
(a vertical interval of-590 m), showing local peaks on the 2200 ft, 1750 ft and 1450 ft le v els.
This observation reflects a fairly constant degree of hydraulic inflation upwards.
(iv) Major (^0.3 m) quartz veins decrease sharply in area upwards between the 850 ft and
175 ft levels (from ~7.0 to 1.5 times the area on the 5600 ft level) confirming that the ore
system dies out towards the surface. The quartz vein area starts to decrease below that of
green carbonate alteration; hence green carbonate alteration persists upwards higher than
X).3 m quartz veins.