Overview of Results from the Greenstone ... - Geology Ontario

Although no significant VMS mineralization has been found in the Genex area since the discovery of
the initial deposit, the area still has potential to host significant VMS mineralization, especially along
strike from the Genex deposit. Geochemically, the Genex felsic metavolcanic rocks are classified as FIIIa
rhyolites, which, according to Lesher et al. (1986), are preferentially associated with Archean VMS
mineralization. Furthermore, the presence of a mineralizing hydrothermal system has already been
established in the area. Thus, many of the necessary components for a VMS deposit are present. Lastly,
the presence of mineralized mudstone lapilli in the volcaniclastic rocks overlying the Genex area is of
interest. Not only is the volcaniclastic sequence a good marker horizon, but the presence of mineralized
fragments indicates that VMS mineralization was still occurring during the evolution of the stratigraphic
package. The source of the mineralized mudstone fragments is not yet identified. In further exploration
for VMS mineralization in the Kamiskotia area, an important feature that must be recognized is the
presence of synvolcanic structures. In the Genex area, the identification of high-level synvolcanic
intrusions is critical in defining the presence of synvolcanic structures. Thus, recognition of synvolcanic
intrusions similar to those of the Genex area, which tend to utilize synvolcanic structures as conduits, is
important in defining synvolcanic structures.
IMPLICATIONS FOR VOLCANOGENIC MASSIVE SULPHIDE EXPLORATION
New U/Pb ages indicate that the Kidd–Munro assemblage rocks in Loveland, Macdiarmid and Thorburn
townships are coeval with the Kidd Volcanic Complex, which hosts the giant Kidd Creek VMS deposit 5
km to the east of the study area. The high-silica FIIIb rhyolites in south-central Loveland Township are
geochemically similar to ore-associated FIIIb rocks from Kidd Creek (e.g., Lesher et al. 1986), and seem
likely to represent the most prospective part of the succession. Volcaniclastic intervals representing lulls
in volcanism during which VMS deposits may have developed have been intersected by drilling. Drilling
has also indicated mineralization associated with the felsic-intermediate volcaniclastic rocks at the top of
the Kidd–Munro assemblage succession, particularly along felsic–mafic contacts at the base of and within
this interval.
Future exploration in the KVC is probably best focussed on the along-strike extension of the known
VMS-hosting interval. Evidence for early movement on the Aconda Lake fault immediately north of the
Genex deposit, and for increased alteration intensity along northeast-trending faults in the Kam-Kotia
Mine area, suggests that synvolcanic faulting may have played an important role in localizing VMS
mineralization. Areas where such faults intersect the VMS-hosting interval may provide a tighter focus
for more detailed exploration. Mafic and felsic volcaniclastic strata, which can be replaced by VMS
mineralization, and felsic coherent facies flows and/or domes, appear to be important potential targets.
Chlorite and/or sericite alteration is associated with VMS orebodies at the Kam-Kotia, Canadian Jamieson
and Genex mines. Although these alteration haloes represent a further exploration guide, they appear to
be relatively areally restricted, and may prove difficult to locate given the sparse outcrop in much of the
study area. Evidence of west-facing in northeast Godfrey and southeast Jamieson townships suggests the
possibility of repetition of the VMS-hosting interval across a map-scale syncline in that area.
Ben Nevis Area Subproject
Katrine, Ben Nevis and Clifford townships are part of the Archean Blake River Group within the Blake
River assemblage of the Abitibi Subprovince. The Blake River Group hosts one of the most significant
mining camps in Canada—the Noranda camp—where the origin, localization, and distribution of deposits
are relatively well understood. In contrast, very little is known about the Blake River Group in Ontario;
hence, this subproject was conceived to improve our knowledge of the Blake River Group in Ontario and
to use that knowledge to assess its potential for VMS mineralization.
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