This uncertainty stems from the difficulty of accurately identifying and
interpreting the nature of the contacts between older and younger volcanic rocks which
all display similar field characteristics. A possible clue, which suggests the direct
deposition of the Bidou and Gem Lake volcanic rocks on the older basement, is the fact
that the Wanipigow Plutonic Complex contains large volumes of equigranular and
locally porphyritic tonalite that is identical in composition and, in one case,in age to the
30
subvolcanic Ross River intrusion (Turek et aI., 1989), in the greenstone belt. This
might be interpreted to indicate that the volcanic rocks of the Rice Lake belt are but one
higher level manifestation of a much wider circa 2730 Ma magmatic arc that extended
well into the Wanipigow Complex where subsequent uplift has resulted in the
preservation of only the deeper roots of the arc........
iii) C02-bearing fluids of similar composition were present during the development of
virtually all veins and shear zones (Diamond, 1989; Diamond et aI., 1989), regardless
of their relative age and gold content. The intensity of carbonatization adjacent to
structures is not directly related to gold deposition nor to progressive changes in fluid
composition. However there is a direct relationship between carbonatization and
fracturing and, in that sense, the recognition of such alteration is a useful guide to
potential auriferous structures, if not to gold itself.
.
