Interpretation & Conclusion
The Andramasina region was a significant gold producing area for 65 years beginning in 1885.
Mining companies and informal miners worked placer and eluvia gold deposits using
unsophisticated methods that provided financial returns with a minimum of investment.
Activities relating to World War Two, the low price of gold in the 1950's and 60's and
uncertainties caused by the country's struggle for political independence discouraged
exploration that may have lead to further gold discoveries. No evidence exists, of companies
active in the Andramasina area testing bedrock mineralization by diamond drilling.
The productive zone in the Andramasina area forms a north-south corridor underlain by
mica-schists and gneisses bounded to the east by granitic bodies and migmatites. The bulk
of production was from stream placers located to the north and south of PAMM's permit area.
Mineralization to the north of the PAMM project is associated with quartz veins ranging from
a few centimeters to several meters in width that have been traced a kilometer or more. These
are found in parallel zones of veins and stringers associated with relatively competent parts
of gneissic country rocks. Gold is accompanied by pyrite dominated sulphide assemblages typical
of deep-seated hydrothermal gold-quartz veins. Grades are not recorded for historical workings
but gold grades, in bedrock veins, were probably below the cut-off grades of the time.
Old workings represent areas of surface gold concentration with bedrock sources that have
never been tested. Alluvial and eluvial surface mining areas are zones of potential bedrock
mineralization and the bedrock mineral potential warrants assessment. The number of informal
workings indicates the entire region has been prospected for visual signs of gold, but the
Andramasina area, a highly prospective area, has never been systematically explored using modern
geochemical or geophysical techniques.
Bedrock mineralization examined by earlier workers shows the destruction of vein selvages
or chloritic sheared margins. Amphibolite grade metamorphism followed the introduction of
gold-bearing quartz veins, but metamorphism has not remobilized gold or associated sulphides.
The geology, vein type and strength of mineralized structures suggest that veins should
continue at depth. Geology, in the Andramasina region, is similar to that found at the Kolar
gold mine in India where the deposits were mined to 3000m in depth over a period of more than
100 years.
French mining companies operated with few of the exploration and exploitation tools
available today and their focus was on placer mining. Bulk mining of low-grade bedrock sources
was not given consideration. Potential remains for finding low grade, bulk-minable surface
deposits. Christopher believes that numerous surface gold concentrations indicate bedrock
potential and that exploration for bedrock gold offers the best potential for advancing the
project.
Exploration Potential
The B7 permit lies within a corridor of gold mineralization that produced extensive placer
deposits on properties located along the corridor to the north and south. Several placer
deposits are reported to have been associated with gold bearing quartz veins in bedrock.
Gold mineralization in the B7 project area is widespread and similar in setting to the better
documented properties along the favorable corridor. Quartz veins and stringer zones are
present on the property and there is a potential for bulk minable mineralization in bedrock
associated with alluvial and eluvial gold.
Initial exploration should focus on regional stream geochemical surveys and a study of
mineral occurrences and old workings. Targets selected should be the subject of grid
geological, geochemical and geophysical surveys and selective overburden drill to define
areas for success contingent diamond drilling.
Conclusions
The Andramasina region was one of Madagascar's main gold mining centers for 65 years beginning
in 1885 with most of production from stream placers and surfaced enriched eluvial deposits.
Primary mineralization, controlled by parallel sets of veins and stringers, has not been
evaluated. The gold mineralization predates, but was not significantly affected by a thermal
event that recrystallized the host strata.
Scars from mining operations mark the traces of possible bedrock sources that remain to
be tested. Quartz veining near old workings suggests potential for stockwork style gold
mineralization.
PAMM's Andramasina project area has potential for mesothermal vein mineralization,
bulk minable alluvial and eluvial gold mineralization and for stockwork gold mineralization
that justifies a systematic exploration program.
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