STEEL RIVER PROPERTY
(Fire Mountain Property)
http://www.phoenixmatachewan.com
Phoenix Matachewan’s Steel River Project is centered on a
large area of Archean greenstone on the north shore of Lake Superior mid-way
between Marathon and Terrace Bay, part of the Abitibi-Wawa subprovince. A major
felsic volcanic centre forms the core of an antiform, and is overlain by a thin,
laterally extensive unit of chert, shale, sulphide iron-formation and related
sedimentary rocks. The Steel River volcanic assemblage is part of the same belt
the Manitouwadge greenstone belt (75 km ENE) and the Big Duck Lakes greenstone
belt (45 km W). Both are well endowed with base metal deposits; the latter
contained over 6 million tonnes of ore, and the former over 65 million tonnes or
ore.
Geology
The felsic volcanic sequence in the Steel River area forms the core of Phoenix
Matachewan’s property. This s is an antiformal sequence of rhyolite flows,
coarse epiclastic breccia, minor pyroclastic strata and some subvolcanic domes
and dykes. The prominent antiformal axis is coincident with strong cleavage
development, with most primary features rotated to parallel the axis. These are
intercalated with mafic flows, and capped by the virtually continuous exhalite
unit mentioned above. The capping exhalite units are overlain by a predominantly
mafic sequence. Our preliminary geochemical compilation indicates that the
felsic strata are “high-temperature” rhyolite (FII-FIIIb Hart et al., 2001, and
the intercalated mafic strata are profoundly Eu-depleted. The latter are mainly
andesite, whereas the overlying mafic flows are basaltic. The felsic strata and
remarkably Na-depleted, and just below the exhalite unit, they are Mn and
base-metal enriched. In summary, the petrochemical data indicate that the strata
are part of a major high-temperature
Mineralization
1. Previous exploration has located several copper-zinc occurrences within the
felsic sequence, near its anticlinal core. Our examination of these indicates
that these are stringer-type zones, surrounded by sericite-chlorite alteration,
and rotated into the plane of schistosity. Immediately below the exhalite unit,
the rocks are broadly manganese enriched, with local base metal enrichment in
several areas. Previous work focused on the stringer-type mineralization (e.g.
the Starhill Zone) and ignored the upper part of the sequence where focused
discharge and massive sulfide deposition appears to have occurred. For example,
in the Bozema Lake area massive sphalerite occurs in the exhalite; this type of
target is the primary focus of Phoenix Matachewan’s program. The past-producing
VMS deposits in both the Manitouwadge (to the east) and Winston Lake (to the
west) areas are both associated with felsic sequences (proximal at Winston,
siliciclastic at Manitouwadge). The presence of possibly laterally equivalent
strata at Steel River, including well developed volcanic breccia, coupled with
excellent geochemical indicators of high-temperature hydrothermal discharge
indicate high VMS potential in the Steel River area.
Our Program
The just completed initial exploration phase was directed to mapping,
prospecting and geochemical sampling of the western half of the area, with a
focus on the exhalite unit and adjacent felsic strata. We re-processed the
recent OGS geophysical survey, and defined 9 linear conductive zones, each about
1 km in strike length, and evenly spaced around the anticlinal structure. All
occur either on or immediately adjacent to the position of the chert-exhalite.
Considerable lithogeochemical data were uncovered in the assessment files; these
data have never previously been plotted or analyzed. To these data we added
about 300 new analyses. Our mapping confirmed the location of the exhalite, and
located several areas of sulfide enrichment. Although the exhalite contains some
units of discontinuous sulfidic shale, it is primarily comprised of chert, and
is chemically similar to the Key Tuffite horizon at Matagami Lake, Quebec. The
core of the anticline is almost completed depleted in sodium. Our
lithogeochemical surveys have identified coincident base metal, potassium,
barium, manganese, phosphate, and negative europium anomalies, all coincident
with conductors that enable us to prioritize the targets for further work. We
are selecting a ground geophysical method that is sufficiently precise to
separate multiple conductors, and identify those that most likely represent
massive sulfide accumulations. Further geochemical data on the eastern part for
the property will be collected this fall, and geophysical surveys and drilling
are planned for the winter. . Dr. J. M. Franklin 13 Sept 2004 Hart, T. R.,
Gibson, H. L., Lesher, C. M., and Campbell, I. H., 2001, Trace element
geochemistry and petrogenesis of felsic metavolcanic rocks associated with
volcanogenic Cu-Zn-Pb massive sulphide deposits, in Anonymous, ed., Geological
Society of America, 2001 annual meeting.
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