New gold targets in the Chibougamau area
The Chibougamau mining camp is characterized by
the presence of a vast layered intrusion, the Lac Doré Complex
(DLC), cored by the Chibougamau Pluton (PDF Format, 64 kb).
The importance of these two elements can be established at many
different levels, whether as the main centre of volcanism, as the
driving force behind the different types of ore deposits, and as
a structural feature that governed response to deformation over
a period of 30 Ma during the Archean (Daigneault, 1998). The crescent-shaped
Chibougamau Pluton occupies the axial part of the Chibougamau anticline.
It represents a multiphase synvolcanic intrusion (2718±2
Ma; Krogh, 1982) derived from the successive emplacement of magmas
differentiated at shallow depths.
Consequently, substantial evidence suggests that
porphyry-type and lode-type occurrences in the Lac Doré
mining camp are products of a single but extensive pre-tectonic
magmatic-hydrothermal ore-generating event, coeval with the emplacement
of the Chibougamau Pluton and the construction of the second volcanic
cycle in the Chibougamau area. The variety of ore deposit types
observed in this mining district, which are particularly well developed
along the northern and southern limbs of the Chibougamau Pluton,
appears to be the result of normal or reverse movement along certain
major faults, and of the local erosion level (Pilote et al., 1998).